text:
Frequent Links
Stellar classification
Template:Image label end In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Light from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines. Each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere. The spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photosphere's temperature and density.
Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest (e.g. A8, A9, F0, F1 form a sequence from hotter to cooler). The sequence has been expanded with classes for other stars and star-like objects that do not fit in the classical system, such class D for white dwarfs and class C for carbon stars.
In the MK system a luminosity class is added to the spectral class using Roman numerals. This is based on the width of certain absorption lines in the star's spectrum which vary with the density of the atmosphere and so distinguish giant stars from dwarfs. Luminosity class 0 or Ia+ stars for hypergiants, class I stars for supergiants, class II for bright giants, class III for regular giants, class IV for sub-giants, class V for main-sequence stars, class sd for sub-dwarfs, and class D for white dwarfs. The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800K.
- 1 Modern classification
- 2 History
- 3 Spectral types
- 4 Extended spectral types
- 4.1 Hot blue emission star classes
- 4.2 Cool red and brown dwarf classes
- 4.3 Carbon-related late giant star classes
- 4.4 White dwarf classifications
- 4.5 Degenerate and exotic stars
- 5 Stellar classification, habitability, and the search for life
- 6 Variable star classification
- 7 See also
- 8 Notes
- 9 References
- 10 External links
Modern classification
The modern classification system is known as the Morgan–Keenan (MK) classification. Each star is assigned a spectral class from the older Harvard spectral classification and a luminosity class using Roman numerals as explained below, forming the star's spectral type.
Harvard spectral classification
The Harvard classification system is a one-dimensional classification scheme using single letters of the alphabet, optionally with numeric subdivisions, to group stars according to their spectral characteristics. Main-sequence stars vary in surface temperature from approximately 2,000 to 50,000 K, whereas more-evolved stars can have temperatures above 100,000 K. Physically, the classes indicate the temperature of the star's atmosphere and are normally listed from hottest to coldest.
|Effective temperature[1][2][3]
|Conventional color description[4][nb 1]
|Actual apparent color[5][6][7]
| Main-sequence mass[1][8]
(solar masses)
| Main-sequence radius[1][8]
(solar radii)
| Main-sequence luminosity[1][8]
| Hydrogen
| Fraction of all
main-sequence stars[9]
|blue white
|deep blue white
|blue white
|yellow white
|yellowish white
|pale yellow orange
|Very weak
|light orange red
|Very weak
The spectral classes O through M, as well as other more specialized classes discussed later, are subdivided by Arabic numerals (0–9), where 0 denotes the hottest stars of a given class. For example, A0 denotes the hottest stars in the A class and A9 denotes the coolest ones. Fractional numbers are allowed; for example, the star Mu Normae is classified as O9.7.[10] The Sun is classified as G2.[11]
The conventional color descriptions are traditional in astronomy, and represent colors relative to the mean color of an A-class star which is considered to be white. The apparent color[5] descriptions are what the observer would see if trying to describe the stars under a dark sky without aid to the eye, or with binoculars. However, most stars in the sky, except the brightest ones, appear white or bluish white to the unaided eye because they are too dim for color vision to work. Red supergiants are cooler and redder than dwarfs of the same spectral type, and stars with particular spectral features such as carbon stars may be far redder than any black body.
O, B, and A stars are sometimes called "early type", whereas K and M stars are said to be "late type″. This stems from an early 20th-century model of stellar evolution in which stars were powered by gravitational contraction via the Kelvin–Helmholtz mechanism whereby stars start their lives as very hot "early-type" stars, and then gradually cool down, evolving into "late-type″ stars. This mechanism provided ages of the Sun that were much smaller than what is observed, and was rendered obsolete by the discovery that stars are powered by nuclear fusion.
The fact that the Harvard classification of a star indicated its surface or photospheric temperature (or more precisely, its effective temperature) was not fully understood until after its development, though by the time the first Hertzsprung–Russell diagram was formulated (by 1914), this was generally suspected to be true.[12] In the 1920s, the Indian physicist Meghnad Saha derived a theory of ionization by extending well-known ideas in physical chemistry pertaining to the dissociation of molecules to the ionization of atoms. First he applied it to the solar chromosphere, then to stellar spectra.[13] The Harvard astronomer Cecilia Helena Payne (later to become Cecilia Payne-Gaposchkin) then demonstrated that the OBAFGKM spectral sequence is actually a sequence in temperature.[14] Because the classification sequence predates our understanding that it is a temperature sequence, the placement of a spectrum into a given subtype, such as B3 or A7, depends upon (largely subjective) estimates of the strengths of absorption features in stellar spectra. As a result, these subtypes are not evenly divided into any sort of mathematically representable intervals.
Yerkes spectral classification

The Yerkes spectral classification, also called the MKK system from the authors' initials, is a system of stellar spectral classification introduced in 1943 by William Wilson Morgan, Philip C. Keenan, and Edith Kellman from Yerkes Observatory.[15] This two-dimensional (temperature and luminosity) classification scheme is based on spectral lines sensitive to stellar temperature and surface gravity which is related to luminosity (whilst the Harvard classification is based on surface temperature only). Later, in 1953, after some revisions of list of standard stars and classification criteria, the scheme was named the Morgan–Keenan classification, or MK (by William Wilson Morgan and Philip C. Keenan's initials),[16] and this system remains the system in modern use today.
Denser stars with higher surface gravity exhibit greater pressure broadening of spectral lines. The gravity, and hence the pressure, on the surface of a giant star is much lower than for a dwarf star because the radius of the giant is much greater than a dwarf of similar mass. Therefore differences in the spectrum can be interpreted as luminosity effects and a luminosity class can be assigned purely from examination of the spectrum.
A number of different luminosity classes are distinguished[17]
- 0 or Ia+ (hypergiants or extremely luminous supergiants). Example: Cygnus OB2#12 (B3-4Ia+)[18]
- Ia (luminous supergiants). Example: Eta Canis Majoris (B5Ia)[19]
- Iab (intermediate luminous supergiants). Example: Gamma Cygni (F8Iab)[20]
- Ib (less luminous supergiants). Example: Zeta Persei (B1Ib)[21]
- II bright giants. Example: Beta Leporis (G0II)[22]
- III normal giants. Example: Arcturus (K0III)[23]
- IV subgiants. Example: Gamma Cassiopeiae (B0.5IVpe)[24]
- V main-sequence stars (dwarfs), Example: Achernar (B6Vep)[21]
- sd (prefix) subdwarfs. Example: HD 149382 (sdB5)[25]
- D (prefix) white dwarfs.[nb 2] Example: van Maanen 2 (DZ8)[26]
Marginal cases are allowed; for example, a star may be either a supergiant or a bright giant, or may be in between the subgiant and main-sequence classifications. In these cases, two special symbols are used: a slash (/) means that a star is either one class or the other, and a dash (-) means that the star is in between the two classes. For example, a star classified as A3-4III/IV would be in between spectral types A3 and A4, while being either a giant star or a subgiant. Sub-dwarf classes have also been used: VI for sub-dwarfs, stars slightly less luminous than the main sequence; VII and sometimes higher numerals for white dwarf or "hot sub-dwarf" classes.
Spectral peculiarities
Additional nomenclature, in the form of lower-case letters, can follow the spectral type to indicate peculiar features of the spectrum.[27]
|Spectral peculiarities for stars
|uncertain spectral value[17]
|Undescribed spectral peculiarities exist
|Special peculiarity
|Composite spectrum[28]
|Emission lines present[28]
|"Forbidden" emission lines present
|"Reversed" center of emission lines weaker than edges
|Emission lines with P Cygni profile
|N III and He II emission[17]
|NIV λ4058Å is stronger than the NIII λ4634Å, λ4640Å, & λ4642Å lines[29]
|SiIV λ4089Å & λ4116Å are emission in addition to the NIII line[29]
|N III emission, absence or weak absorption of He II
|Displays strong HeII absorption accompanied by weak NIII emissions[31]
|WR stars with emission lines due to hydrogen.[32]
|WR stars with hydrogen emissions seen on both absorption and emission.[32]
|He wk
|Weak He lines
|Spectra with interstellar absorption features
|Enhanced metal features[28]
|Broad ("nebulous") absorption due to spinning[28]
|Very broad absorption features[17]
|A nebula's spectrum mixed in[28]
|Unspecified peculiarity, peculiar star.[nb 3][28]
|Peculiar spectrum, similar to the spectra of novae
|Red & blue shifts line present
|Narrowly "sharp" absorption lines[28]
|Very narrow lines
|Shell star features[28]
|Variable spectral feature[28] (sometimes abbreviated to "v")
|Weak lines[28] (also "w" & "wk")
| Element
|Abnormally strong spectral lines of the specified element(s)[28]
For example, 59 Cygni is listed as spectral type B1.5Vnne,[33] indicating a spectrum with the general classification B1.5V, as well as very broad absorption lines and certain emission lines.
The reason for the odd arrangement of letters in the Harvard classification is historical, having evolved from the earlier Secchi classes and been progressively modified as understanding improved.
Secchi classes
During the 1860s and 1870s, pioneering stellar spectroscopist Angelo Secchi created the Secchi classes in order to classify observed spectra. By 1866, he had developed three classes of stellar spectra:[34][35][36]
- Class I: white and blue stars with broad heavy hydrogen lines, such as Vega and Altair. This includes the modern class A and early class F.
- Class II: yellow stars—hydrogen less strong, but evident metallic lines, such as the Sun, Arcturus, and Capella. This includes the modern classes G and K as well as late class F.
- Class III: orange to red stars with complex band spectra, such as Betelgeuse and Antares. This corresponds to the modern class M.
In 1868, he discovered carbon stars, which he put into a distinct group:[37]
- Class IV: red stars with significant carbon bands and lines (carbon stars.)
In 1877, he added a fifth class:[38]
- Class V: emission-line stars, such as γ Cassiopeiae and Sheliak.
In the late 1890s, this classification began to be superseded by the Harvard classification, which is discussed in the remainder of this article.[39][40][41] The roman numerals used for Secchi classes should not be confused with the completely unrelated roman numerals used for Yerkes luminosity classes.
Draper system
|Hydrogen lines dominant.
|Did not appear in the catalogue.
|Wolf–Rayet spectra with bright lines.
|Planetary nebulae.
|Other spectra.
In the 1880s, the astronomer Edward C. Pickering began to make a survey of stellar spectra at the Harvard College Observatory, using the objective-prism method. A first result of this work was the Draper Catalogue of Stellar Spectra, published in 1890. Williamina Fleming classified most of the spectra in this catalogue. It used a scheme in which the previously used Secchi classes (I to IV) were divided into more specific classes, given letters from A to N. Also, the letters O, P and Q were used, O for stars whose spectra consisted mainly of bright lines, P for planetary nebulae, and Q for stars not fitting into any other class.[42][43]
Harvard system
In 1897, another worker at Harvard, Antonia Maury, placed the Orion subtype of Secchi class I ahead of the remainder of Secchi class I, thus placing the modern type B ahead of the modern type A. She was the first to do so, although she did not use lettered spectral types, but rather a series of twenty-two types numbered from I to XXII.[44][45]
In 1901, Annie Jump Cannon returned to the lettered types, but dropped all letters except O, B, A, F, G, K, and M, used in that order, as well as P for planetary nebulae and Q for some peculiar spectra. She also used types such as B5A for stars halfway between types B and A, F2G for stars one-fifth of the way from F to G, and so forth.[46][47] Finally, by 1912, Cannon had changed the types B, A, B5A, F2G, etc. to B0, A0, B5, F2, etc.[48][49] This is essentially the modern form of the Harvard classification system. A common mnemonic for remembering the spectral type letters is "Oh, Be A Fine Guy/Girl, Kiss Me".
Spectral types
Class O
Class O stars are very hot and extremely luminous, with most of their radiated output in the ultraviolet range. These are the rarest of all main-sequence stars. About 1 in 3,000,000 (0.00003%) of the main-sequence stars in the solar neighborhood are class O stars.[nb 4][9] Some of the most massive stars lie within this spectral class. Class O stars frequently have complicated surroundings which make measurement of their spectra difficult.
O-type spectra used to be defined by the ratio of the strength of the He II λ4541 relative to that of He I λ4471, where λ is the wavelength, measured in ångströms. Spectral type O7 was defined to be the point at which the two intensities are equal, with the He I line weakening towards earlier types. Type O3 was, by definition, the point at which said line disappears altogether, although it can be seen very faintly with modern technology. Due to this, the modern definition uses the ratio of the nitrogen line N IV λ4058 to N III λλ4634-40-42.[50]
O stars have dominant lines of absorption and sometimes emission for He II lines, prominent ionized (Si IV, O III, N III, and C III) and neutral helium lines, strengthening from O5 to O9, and prominent hydrogen Balmer lines, although not as strong as in later types. Because they are so massive, class O stars have very hot cores and burn through their hydrogen fuel very quickly, so they are the first stars to leave the main sequence.
When the MKK classification scheme was first described in 1943, the only subtypes of class O used were O5 to O9.5.[51] The MKK scheme was extended to O9.7 in 1971[52] and O4 in 1978,[53] and new classification schemes have subsequently been introduced which add types O2, O3 and O3.5.[54]
- Spectral standards:[55]
- O7V: S Monocerotis
- O9V: 10 Lacertae
Class B
Class B stars are very luminous and blue. Their spectra have neutral helium, which are most prominent at the B2 subclass, and moderate hydrogen lines. As O and B stars are so energetic, they only live for a relatively short time. Thus, due to the low probability of kinematic interaction during their lifetime, they do not, and are unable to, stray far from the area in which they were formed, apart from runaway stars.
The transition from class O to class B was originally defined to be the point at which the He II λ4541 disappears. However, with today's better equipment, the line is still apparent in the early B stars. Today for main-sequence stars, the B-class is instead defined by the intensity of of the He I violet spectrum, with the maximum intensity corresponding to class B2. For supergiants, lines of silicon are used instead; the Si IV λ4089 and Si III λ4552 lines are indicative of early B. At mid B, the intensity of the latter relative to that of Si II λλ4128-30 is the defining characteristic, while for late B, it is the intensity of Mg II λ4481 relative to that of He I λ4471[50]
These stars tend to be found in their originating OB associations, which are associated with giant molecular clouds. The Orion OB1 association occupies a large portion of a spiral arm of the Milky Way and contains many of the brighter stars of the constellation Orion. About 1 in 800 (0.125%) of the main-sequence stars in the solar neighborhood are class B stars.[nb 4][9]
- Spectral standards:[55]
- B0V: Upsilon Orionis
- B0Ia: Alnilam
- B2Ia: Chi2 Orionis
- B2Ib: 9 Cephei
- B3V: Eta Ursae Majoris
- B3V: Eta Aurigae
- B3Ia: Omicron2 Canis Majoris
- B5Ia: Eta Canis Majoris
- B8Ia: Rigel
Class A
Class A stars are among the more common naked eye stars, and are white or bluish-white. They have strong hydrogen lines, at a maximum by A0, and also lines of ionized metals (Fe II, Mg II, Si II) at a maximum at A5. The presence of Ca II lines is notably strengthening by this point. About 1 in 160 (0.625%) of the main-sequence stars in the solar neighborhood are class A stars.[nb 4][9][56]
- Spectral standards:[55]
- A0Van: Gamma Ursae Majoris
- A0Va: Vega
- A0Ib: Eta Leonis
- A0Ia: HD 21389
- A2Ia: Deneb
- A3Va: Fomalhaut
Class F
Class F stars have strengthening H and K lines of Ca II. Neutral metals (Fe I, Cr I) beginning to gain on ionized metal lines by late F. Their spectra are characterized by the weaker hydrogen lines and ionized metals. Their color is white. About 1 in 33 (3.03%) of the main-sequence stars in the solar neighborhood are class F stars.[nb 4][9]
- Spectral standards:[55]
- F0IIIa: Zeta Leonis
- F0Ib: Alpha Leporis
- F2V: 78 Ursae Majoris
Class G
Class G stars, including the Sun[11] have prominent H and K lines of Ca II, which are most pronounced at G2. They have even weaker hydrogen lines than F, but along with the ionized metals, they have neutral metals. There is a prominent spike in the G band of CH molecules. Class G main-sequence stars make up about 7.5%, nearly one in thirteen, of the main-sequence stars in the solar neighborhood.[nb 4][9]
G is host to the "Yellow Evolutionary Void".[57] Supergiant stars often swing between O or B (blue) and K or M (red). While they do this, they do not stay for long in the yellow supergiant G classification as this is an extremely unstable place for a supergiant to be.
- Spectral standards:[55]
- G0V: Beta Canum Venaticorum
- G0IV: Eta Boötis
- G0Ib: Beta Aquarii
- G2V: Sun
- G5V: Kappa Ceti
- G5IV: Mu Herculis
- G5Ib: 9 Pegasi
- G8V: 61 Ursae Majoris
- G8IV: Beta Aquilae
- G8IIIa: Kappa Geminorum
- G8IIIab: Epsilon Virginis
- G8Ib: Epsilon Geminorum
Class K
- "K STAR" redirects here. For the Korean nuclear fusion project, see KSTAR.
Class K stars are orangish stars that are slightly cooler than the Sun. They make up about 12%, nearly one in eight, of the main-sequence stars in the solar neighborhood.[nb 4][9] There are also giant K-type stars, which range from hypergiants like RW Cephei, to giants and supergiants, such as Arcturus, whereas orange dwarfs, like Alpha Centauri B, are main-sequence stars.
They have extremely weak hydrogen lines, if they are present at all, and mostly neutral metals (Mn I, Fe I, Si I). By late K, molecular bands of titanium oxide become present. There is a suggestion that K Spectrum stars may potentially increase the chances of life developing on orbiting planets that are within the habitable zone.[58]
- Spectral standards:[55]
- K0V: Sigma Draconis
- K0III: Pollux
- K0III: Epsilon Cygni
- K2V: Epsilon Eridani
- K2III: Kappa Ophiuchi
- K3III: Rho Boötis
- K5V: 61 Cygni A
- K5III: Gamma Draconis
Class M
Class M stars are by far the most common. About 76% of the main-sequence stars in the Solar neighborhood are class M stars.[nb 4][nb 5][9] However, because main-sequence stars of spectral class M have such low luminosities, none are bright enough to be visible to see with the unaided eye unless under exceptional conditions. The brightest known M-class main-sequence star is M0V Lacaille 8760 at magnitude 6.6 (the limiting magnitude for typical naked-eye visibility under good conditions is typically quoted as 6.5) and it is extremely unlikely that any brighter examples will be found.
Although most class M stars are red dwarfs, the class also hosts most giants and some supergiants such as VY Canis Majoris, Antares and Betelgeuse. Furthermore, the late-M group holds hotter brown dwarfs that are above the L spectrum. This is usually in the range of M6.5 to M9.5. The spectrum of a class M star shows lines belonging to oxide molecules, TiO in particular, in the visible and all neutral metals, but absorption lines of hydrogen are usually absent. TiO bands can be strong in class M stars, usually dominating their visible spectrum by about M5. Vanadium monoxide bands become present by late M.
- Spectral standards:[55]
- M0IIIa: Beta Andromedae
- M2III: Chi Pegasi
- M1-M2Ia-Iab: Betelgeuse
- M2Ia: Mu Cephei
Extended spectral types
A number of new spectral types have been taken into use from newly discovered types of stars.[59]
Hot blue emission star classes
Spectra of some very hot and bluish stars exhibit marked emission lines from carbon or nitrogen, or sometimes oxygen.
Class W: Wolf–Rayet
Class W or WR represents the Wolf–Rayet stars, notable for spectra lacking hydrogen lines. Instead their spectra are dominated by broad emission lines of highly ionized helium, nitrogen, carbon and sometimes oxygen. They are thought to mostly be dying supergiants with their hydrogen layers blown away by stellar winds, thereby directly exposing their hot helium shells. Class W is further divided into sub classes according to the relative strength of nitrogen and carbon emission lines in their spectra (and outer layers).[32]
WR spectra range is listed below:[61][62]
- WN,[32] spectrum dominated by NitrogenIII-V and HeliumI-II lines
- WNE (WN2 to WN5 with some WN6), hotter or "early"
- WNL (WN7 to WN9 with some WN6), cooler or "late"
- Extended WN classes WN10 and WN11 sometimes used for the Ofpe/WN9 stars[32]
- h tag used (e.g. WN9h) for WR with hydrogen emission and ha (e.g. WN6ha) for both hydrogen emission and absorption
- WN/C, WN stars plus strong CarbonIV lines, intermediate between WN and WC stars[32]
- WC,[32] spectrum with strong CarbonII-IV lines
- WCE (WC4 to WC6), hotter or "early"
- WCL (WC7 to WC9), cooler or "late"
- WO (WO1 to WO4), strong OxygenVI lines, extremely rare
Although the central stars of most planetary nebulae (CSPNe) show O-type spectra,[63] around 10% are hydrogen-deficient and show WR spectra.[64] These are low mass stars and to distinguish them from the massive Wolf Rayet stars, their spectra are enclosed in square brackets: e.g. [WC]. Most of these show [WC] spectra, some [WO], and very rarely [WN].
Wolf–Rayet examples:
- Example: R136a1 (WN5h)
- Example: Gamma2 Velorum A (WC8)
- Example: WR93B (WO3)
The "Slash" stars
The slash stars are stars with O-type spectra and WN sequence in their spectra. The name slash comes from their spectra having a slash.
- Example spectra: Of/WNL[50]
There is a secondary group found with this spectra, a cooler, "intermediate" group with designation of Ofpe/WN9.[50] These stars have also been referred to as WN10 or WN11, but that has become less popular with the realisation of the evolutionary difference to other Wolf–Rayet stars. Recent discoveries of even rarer stars have extended the range of slash stars as far as O2-3.5If*/WN5-7, which are even hotter than the original slash stars.[65]
Cool red and brown dwarf classes
The new spectral types L, T and Y were created to classify infrared spectra of cool stars. This includes both red dwarfs and brown dwarfs that are very faint in the visual spectrum.[66]
Brown dwarfs, whose energy comes from gravitational attraction alone, cool as they age and so progress to later spectral types. Brown dwarfs start their lives with M-type spectra and will cool through the L, T, and Y spectral classes; faster the less massive they are—the highest-mass brown dwarfs cannot have cooled to Y or even T dwarfs within the age of the universe. Because this leads to a degeneracy between mass and age for a given effective temperature and luminosity, no unique values can be assigned to a given spectral type.[8]
Class L
Class L dwarfs get their designation because they are cooler than M stars and L is the remaining letter alphabetically closest to M. Some of these objects have masses large enough to support hydrogen fusion and are therefore stars, but most are of substellar mass and are therefore brown dwarfs. They are a very dark red in color and brightest in infrared. Their atmosphere is cool enough to allow metal hydrides and alkali metals to be prominent in their spectra.[67][68][69] Due to low gravities in giant stars, TiO- and VO-bearing condensates never form. Thus, larger L-type stars can never form in an isolated environment. It may be possible for these L-type supergiants to form through stellar collisions, however, an example of which is V838 Monocerotis.
- L: 1,300–2,400 K, dwarfs (some stellar, some substellar) with metal hydrides and alkali metals prominent in their spectra.
- Example: VW Hyi
- Example: 2MASSW J0746425+2000321 binary[70]
- Component A is an L dwarf star
- Component B is an L brown dwarf
- Example: LSR 1610-0040 (subdwarf)[71]
- Example: V838 Monocerotis (supergiants)

Class T: methane dwarfs
Class T dwarfs are cool brown dwarfs with surface temperatures between approximately 700 and 1,300 K. Their emission peaks in the infrared. Methane is prominent in their spectra.[67][68]
- T: ~500–1,300 K, cooler brown dwarfs with methane in the spectrum
- Examples: SIMP 0136 (the brightest T dwarf discovered in northern hemisphere)[72]
- Examples: Epsilon Indi Ba & Epsilon Indi Bb
- Examples: CFBDS 1448 a T dwarf with an exoplanet orbiting it
Class T and L could be more common than all the other classes combined if recent research is accurate. Study of the number of proplyds (protoplanetary discs, clumps of gas in nebulae from which stars and planetary systems are formed) indicates that the number of stars in the galaxy should be several orders of magnitude higher than what we know about. It is theorized that these proplyds are in a race with each other. The first one to form will become a proto-star, which are very violent objects and will disrupt other proplyds in the vicinity, stripping them of their gas. The victim proplyds will then probably go on to become main-sequence stars or brown dwarfs of the L and T classes, which are quite invisible to us. Because brown dwarfs can live so long, these smaller bodies accumulate over time.
Class Y
Brown dwarfs of spectral class Y are cooler than those of spectral class T and have qualitatively different spectra from them. A total of 17 objects have been placed in class Y as of August 2013.[73] Although such dwarfs have been modelled[74] and detected within forty light years by the Wide-field Infrared Survey Explorer (WISE)[59][75][76][77][78] there is no well-defined spectral sequence yet with prototypes. Nevertheless, several objects have been assigned spectral classes Y0, Y1, and Y2.[79] The spectra of these objects display absorption around 1.55 micrometers.[80] Delorme et al. has suggested that this feature is due to absorption from ammonia and that this should be taken as indicating the T–Y transition, making these objects of type Y0.[80][81] In fact, this ammonia-absorption feature is the main criterion that has been adopted to define this class.[79] However, this feature is difficult to distinguish from absorption by water and methane,[80] and other authors have stated that the assignment of class Y0 is premature.[82]
- Y: < 600 K, ultra-cool brown dwarfs
- Example: WISE 0410+1502, class Y0
- Example: WISE 0350-5658, class Y1
- Example: WISE 1405+5534, class Y1
The brown dwarf with the latest assigned spectral type, WISE 1828+2650, is a >Y2 dwarf with an effective temperature originally estimated around 300 K, the temperature of the human body.[75][76][83] Parallax measurements have however since shown that its luminosity is inconsistent with it being colder than ~400 K; the likely coolest Y dwarf currently known is WD 0806−661B with approximately 350 K.[2]
The mass range for Y dwarfs is 9–25 Jupiter masses, but for young objects might reach below one Jupiter mass, which means that Y class objects straddle the 13 Jupiter mass deuterium-fusion limit that marks the division between brown dwarfs and planets.[79]
Carbon-related stars are stars whose spectra indicate production of carbon by helium triple-alpha fusion. With increased carbon abundance, and some parallel s-process heavy element production, the spectra of these stars become increasingly deviant from the usual late spectral classes G, K and M. The giants among those stars are presumed to produce this carbon themselves, but not too few of this class of stars are believed to be double stars whose odd atmosphere once was transferred from a former carbon star companion that is now a white dwarf.
Class C: carbon stars
Originally classified as R and N stars, these are also known as 'carbon stars'. These are red giants, near the end of their lives, in which there is an excess of carbon in the atmosphere. The old R and N classes ran parallel to the normal classification system from roughly mid G to late M. These have more recently been remapped into a unified carbon classifier C with N0 starting at roughly C6. Another subset of cool carbon stars are the J-type stars, which are characterized by the strong presence of molecules of 13CN in addition to those of 12CN.[84] A few dwarf (that is, main-sequence) carbon stars are known, but the overwhelming majority of known carbon stars are giants or supergiants.
- C: Carbon stars, e.g. R CMi
- C-R: Formerly a class on its own representing the carbon star equivalent of late G to early K stars. Example: S Camelopardalis
- C-N: Formerly a class on its own representing the carbon star equivalent of late K to M stars. Example: R Leporis
- C-J: A subtype of cool C stars with a high content of 13C. Example: Y Canum Venaticorum
- C-H: Population II analogues of the C-R stars. Examples: V Ari, TT CVn[85]
- C-Hd: Hydrogen-Deficient Carbon Stars, similar to late G supergiants with CH and C2 bands added. Examples: HD 137613, R Coronae Borealis
Class S
Class S stars have zirconium monoxide lines in addition to (or, rarely, instead of) those of titanium monoxide, and are in between the class M stars and the carbon stars.[86] S stars have excess amounts of zirconium and other elements produced by the s-process, and have their carbon and oxygen abundances closer to equal than is the case for M stars. The latter condition results in both carbon and oxygen being locked up almost entirely in carbon monoxide molecules. For stars cool enough for carbon monoxide to form that molecule tends to "eat up" all of whichever element is less abundant, resulting in "leftover oxygen" (which becomes available to form titanium oxide) in stars of normal composition, "leftover carbon" (which becomes available to form the diatomic carbon molecules) in carbon stars, and "leftover nothing" in the S stars. The relation between these stars and the ordinary M stars indicates a continuum of carbon abundance. Like carbon stars, nearly all known S stars are giants or supergiants.
- Examples: S Ursae Majoris, BD Camelopardalis
In between the M class and the S class, border cases are named MS stars. In a similar way border cases between the S class and the C-N class are named SC or CS. The sequence M → MS → S → SC → C-N is believed to be a sequence of increased carbon abundance with age for carbon stars in the asymptotic giant branch.
- Examples: R Serpentis, ST Monocerotis (MS)
- Examples: CY Cygni, BH Crucis (SC)
White dwarf classifications
The class D (for Degenerate) is the modern classification used for white dwarfs – low-mass stars that are no longer undergoing nuclear fusion and have shrunk to planetary size, slowly cooling down. Class D is further divided into spectral types DA, DB, DC, DO, DQ, DX, and DZ. The letters are not related to the letters used in the classification of other stars, but instead indicate the composition of the white dwarf's visible outer layer or atmosphere.
- Examples: Sirius B (DA2), Procyon B (DA4), Van Maanen 2 (DZ7)[87], Table 1
The white dwarf types are as follows:[88][89]
- DA: a hydrogen-rich atmosphere or outer layer, indicated by strong Balmer hydrogen spectral lines.
- DB: a helium-rich atmosphere, indicated by neutral helium, He I, spectral lines.
- DO: a helium-rich atmosphere, indicated by ionized helium, He II, spectral lines.
- DQ: a carbon-rich atmosphere, indicated by atomic or molecular carbon lines.
- DZ: a metal-rich atmosphere, indicated by metal spectral lines (a merger of the obsolete white dwarf spectral types, DG, DK and DM).
- DC: no strong spectral lines indicating one of the above categories.
- DX: spectral lines are insufficiently clear to classify into one of the above categories.
The type is followed by a number giving the white dwarf's surface temperature. This number is a rounded form of 50400/Teff, where Teff is the effective surface temperature, measured in kelvins. Originally, this number was rounded to one of the digits 1 through 9, but more recently fractional values have started to be used, as well as values below 1 and above 9.[88][90]
Two or more of the type letters may be used to indicate a white dwarf which displays more than one of the spectral features above.[88]
Extended white dwarf spectral types:[88]
- DAB: a hydrogen- and helium-rich white dwarf displaying neutral helium lines.
- DAO: a hydrogen- and helium-rich white dwarf displaying ionized helium lines.
- DAZ: a hydrogen-rich metallic white dwarf.
- DBZ: a helium-rich metallic white dwarf.
A different set of spectral peculiarity symbols are used for white dwarfs than for other types of stars:
|Spectral peculiarities for stars
|Magnetic white dwarf with detectable polarization
|Emission lines present
|Magnetic white dwarf without detectable polarization
|Spectral peculiarities exist
Degenerate and exotic stars
These objects are not stars but are stellar remnants. They are much dimmer and if placed on the HR diagram, would be placed further to the lower left-hand corner.[91]
Stellar classification, habitability, and the search for life
Stability, luminosity, and lifespan are all factors in stellar habitability. We only know of one star that hosts life, the Sun, a G-class main-sequence star with an abundance of heavy elements and low variability in brightness. It is also unlike many stellar systems in that there is only one star in its system.
Working from these constraints and the problems of having an empirical sample set of only one, the range of stars that are predicted to be able to support life as we know it is limited by a few factors. Of the main-sequence star types, stars more massive than 1.5 times that of the Sun (spectral types O, B, and A) age too quickly for advanced life to develop (using Earth as a guideline). On the other extreme, dwarfs of less than half the mass of the Sun (spectral type M) are likely to tidally lock planets within their habitable zone, along with other problems (see Habitability of red dwarf systems).[92] Although there are many problems facing life on red dwarfs, due to their sheer numbers and longevity many astronomers continue to model these systems.
For these reasons NASA's Kepler Mission has been searching for habitable planets mainly at main-sequence stars that are less massive than spectral type A but more massive than type M—i.e. main-sequence stars of types F, G, and K, the most probable stars to host life.[92]
Variable star classification
Stars that exhibit change in luminosity are variable stars. There is a variable star classification scheme that encompasses existing stars that are classified in the spectra classification.
See also
- Astrograph
- Guest star
- Spectral signature
- Stellar evolution
- Star count, survey of stars
- UBV photometric system
- ^ The conventional color description takes into account only the peak of the stellar spectrum. However, in actuality stars radiate in all parts of the spectrum, and because all spectral colors combined appear white, the actual apparent colors the human eye would observe are lighter than the conventional color descriptions.
- ^ Use a different set of spectral types from element-burning stars
- ^ When used with A-type stars, this instead refers to abnormally strong metallic spectral lines
- ^ a b c d e f g These proportions are fractions of stars brighter than absolute magnitude 16; lowering this limit will render earlier types even rarer, whereas generally adding only to the M class.
- ^ This rises to 78.6% if we include all stars. (See the above note.)
- ^ a b c d Tables VII, VIII, Empirical bolometric corrections for the main-sequence, G. M. H. J. Habets and J. R. W. Heinze, Astronomy and Astrophysics Supplement Series 46 (November 1981), pp. 193–237, Bibcode: 1981A&AS...46..193H. Luminosities are derived from Mbol figures, using Mbol(☉)=4.75.
- ^ a b T. J. Dupuy & A. L. Kraus (2013). "Distances, Luminosities, and Temperatures of the Coldest Known Substellar Objects". Science. published online 5 September 2013 (6153): 1492–1495. Bibcode:2013Sci...341.1492D. arXiv:1309.1422. doi:10.1126/science.1241917.
- ^ Carsten Weidner; Jorick Vink (2010). "The masses, and the mass discrepancy of O-type stars". Astronomy & Astrophysics 524: A98. Bibcode:2010A&A...524A..98W. arXiv:1010.2204v1. doi:10.1051/0004-6361/201014491.
- ^ "The Colour of Stars". Australia Telescope National Facility.
- ^ a b The Guinness book of astronomy facts & feats, Patrick Moore, 1992, 0-900424-76-1
- ^ "The Colour of Stars". Australia Telescope Outreach and Education. 2004-12-21. Retrieved 2007-09-26. — Explains the reason for the difference in color perception.
- ^ Charity, Mitchell. "What color are the stars?". Retrieved 2006-05-13.
- ^ a b c d Baraffe; Chabrier; Barman; Allard & Hauschildt (2003). "Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 209458". Astronomy and Astrophysics 402 (2): 701. Bibcode:2003A&A...402..701B. arXiv:astro-ph/0302293. doi:10.1051/0004-6361:20030252.
- ^ a b c d e f g h LeDrew, G.; The Real Starry Sky, Journal of the Royal Astronomical Society of Canada, Vol. 95, No. 1 (whole No. 686, February 2001), pp. 32–33. Note: Table 2 has an error and so this article will use 824 as the assumed correct total of main-sequence stars
- ^ Sota, A.; Apellániz, J. Maíz; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J. (2014). "The Galactic O-Star Spectroscopic Survey (Gosss). Ii. Bright Southern Stars". The Astrophysical Journal Supplement Series 211: 10. Bibcode:2014ApJS..211...10S. doi:10.1088/0067-0049/211/1/10.
- ^ a b Phillips, K. J. H. (1995). Guide to the Sun. Cambridge University Press. pp. 47–53. ISBN 978-0-521-39788-9.
- ^ Relations Between the Spectra and Other Characteristics of the Stars, Henry Norris Russell, Popular Astronomy 22, no. 5, (May 1914), pp. 275–294, Bibcode: 1914PA.....22..275R, in particular p.277
- ^ Saha, M. N.; On a Physical Theory of Stellar Spectra, Proceedings of the Royal Society of London, Series A, Volume 99, Issue 697 (May 1921), pp. 135–153
- ^ Payne, C. H.; Stellar Atmospheres; A Contribution to the Observational Study of High Temperature in the Reversing Layers of Stars, Ph. D. Thesis, Radcliffe College, 1925
- ^ Morgan, William Wilson; Keenan, Philip Childs; Kellman, Edith (1943), "An atlas of stellar spectra, with an outline of spectral classification", Chicago, Ill., The University of Chicago press
- ^ Philip C. Keenan, William Wilson Morgan; Keenan, P C (1973). "Spectral Classification". Annual Reviews of Astronomy and Astrophysics (Annual Reviews) 11 (1): 29–50. Bibcode:1973ARA&A..11...29M. doi:10.1146/annurev.aa.11.090173.000333.
- ^ a b c d "A note on the spectral atlas and spectral classification". Centre de données astronomiques de Strasbourg. Retrieved 2 January 2015.
- ^ Caballero-Nieves, S. M.; Nelan, E. P.; Gies, D. R.; Wallace, D. J.; Degioia-Eastwood, K.; Herrero, A.; Jao, W. -C.; Mason, B. D.; Massey, P.; Moffat, A. F. J.; Walborn, N. R. (2014). "A High Angular Resolution Survey of Massive Stars in Cygnus Ob2: Results from Thehubble Space Telescopefine Guidance Sensors". The Astronomical Journal 147 (2): 40. doi:10.1088/0004-6256/147/2/40.
- ^ Prinja, R. K.; Massa, D. L. (2010). "Signature of wide-spread clumping in B supergiant winds". Astronomy and Astrophysics 521: L55. doi:10.1051/0004-6361/201015252.
- ^ Gray, D. F. (2010). "PHOTOSPHERIC VARIATIONS OF THE SUPERGIANT γ Cyg". The Astronomical Journal 140 (5): 1329. doi:10.1088/0004-6256/140/5/1329.
- ^ a b Nazé, Y. (2009). "Hot stars observed by XMM-Newton". Astronomy and Astrophysics 506 (2): 1055. doi:10.1051/0004-6361/200912659.
- ^ Lyubimkov, L. S. et al. (2010). "Accurate fundamental parameters for A-, F- and G-type Supergiants in the solar neighbourhood". Monthly Notices of the Royal Astronomical Society 402 (2): 1369–1379. Bibcode:2010MNRAS.402.1369L. arXiv:0911.1335. doi:10.1111/j.1365-2966.2009.15979.x.
- ^ Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Robinson, P. E. (2003). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I". The Astronomical Journal 126 (4): 2048. doi:10.1086/378365.
- ^ Cenarro, A. J.; Peletier, R. F.; Sanchez-Blazquez, P.; Selam, S. O.; Toloba, E.; Cardiel, N.; Falcon-Barroso, J.; Gorgas, J.; Jimenez-Vicente, J.; Vazdekis, A. (2007). "Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters". Monthly Notices of the Royal Astronomical Society 374 (2): 664. doi:10.1111/j.1365-2966.2006.11196.x.
- ^ Sion, Edward M.; Holberg, J. B.; Oswalt, Terry D.; McCook, George P.; Wasatonic, Richard (2009). "The White Dwarfs Within 20 Parsecs of the Sun: Kinematics and Statistics". The Astronomical Journal 138 (6): 1681–1689. Bibcode:2009AJ....138.1681S. arXiv:0910.1288. doi:10.1088/0004-6256/138/6/1681.
- ^ SkyTonight: The Spectral Types of Stars
- ^ a b c d e f g h i j k Allen, J. S. "The Classification of Stellar Spectra". UCL Department of Physics and Astronomy: Astrophysics Group. Retrieved 1 January 2014.
- ^ a b Pismis 24-1: The Stellar Upper Mass Limit Preserved, J. Maíz Apellániz et al. 2006
- ^ a b Spectroscopic study of the N159/N160 complex in the Large Magellanic Cloud, Cecilia Fariña et al. 2009
- ^ Early-type stars in the core of the young open cluster Westerlund2, G.Rauw et al. 2006
- ^ a b c d e f g Physical Properties of Wolf–Rayet Stars, Crowther, Paul A., 2007
- ^ Rountree Lesh, J. (1968). "The Kinematics of the Gould Belt: An Expanding Group?". The Astrophysical Journal Supplement Series 17: 371. doi:10.1086/190179.
- ^ Analyse spectrale de la lumière de quelques étoiles, et nouvelles observations sur les taches solaires, P. Secchi, Comptes Rendus des Séances de l'Académie des Sciences 63 (July–December 1866), pp. 364–368.
- ^ Nouvelles recherches sur l'analyse spectrale de la lumière des étoiles, P. Secchi, Comptes Rendus des Séances de l'Académie des Sciences 63 (July–December 1866), pp. 621–628.
- ^ pp. 60, 134, The Analysis of Starlight: One Hundred and Fifty Years of Astronomical Spectroscopy, J. B. Hearnshaw, Cambridge, UK: Cambridge University Press, 1986, ISBN 0-521-25548-1.
- ^ pp. 62–63, Hearnshaw 1986.
- ^ p. 60, Hearnshaw 1986.
- ^ Classification of Stellar Spectra: Some History
- ^ pp. 62–63, Stars and Their Spectra: An Introduction to the Spectral Sequence, James B. Kaler, Cambridge: Cambridge University Press, 1997, ISBN 0-521-58570-8.
- ^ p. 60–63, Hearnshaw 1986; pp. 623–625, Secchi 1866.
- ^ a b The Draper Catalogue of stellar spectra photographed with the 8-inch Bache telescope as a part of the Henry Draper memorial, Edward C. Pickering, Annals of Harvard College Observatory 27 (1890), Bibcode: 1890AnHar..27....1P. See in particular pp. 1–4.
- ^ a b pp. 106–108, Hearnshaw 1986.
- ^ pp. 111–112, Hearnshaw 1986.
- ^ Spectra of bright stars photographed with the 11-inch Draper Telescope as part of the Henry Draper Memorial, Antonia C. Maury and Edward C. Pickering, Annals of Harvard College Observatory 28, part 1 (1897), pp. 1–128, Bibcode: 1897AnHar..28....1M; see in particular Table I.
- ^ Spectra of bright southern stars photographed with the 13-inch Boyden telescope as part of the Henry Draper Memorial, Annie J. Cannon and Edward C. Pickering, Annals of Harvard College Observatory 28, part 2 (1901), pp. 129–263, Bibcode: 1901AnHar..28..129C; see in particular pp. 139–143.
- ^ pp. 117–119, Hearnshaw 1986.
- ^ Classification of 1,688 southern stars by means of their spectra, Annie Jump Cannon and Edward C. Pickering, Annals of Harvard College Observatory 56, #5 (1912), pp. 115–164, Bibcode: 1912AnHar..56..115C.
- ^ pp. 121–122, Hearnshaw 1986.
- ^ a b c d . Bibcode:2008RMxAC..33....5W. Missing or empty
- ^ An atlas of stellar spectra, with an outline of spectral classification, W. W. Morgan, P. C. Keenan and E. Kellman, Chicago: The University of Chicago Press, 1943.
- ^ Walborn, N. R. (1971). "Some Spectroscopic Characteristics of the OB Stars: An Investigation of the Space Distribution of Certain OB Stars and the Reference Frame of the Classification". The Astrophysical Journal Supplement Series 23: 257. doi:10.1086/190239.
- ^ Revised MK Spectral Atlas for Stars Earlier than the Sun, W. W. Morgan, H. A. Abt, and J. W. Tapscott, Yerkes Observatory, University of Chicago and Kitt Peak National Observatory, 1978.
- ^ A New Spectral Classification System for the Earliest O Stars: Definition of Type O2, Nolan R. Walborn et al., The Astronomical Journal 123, #5 (May 2002), pp. 2754–2771, doi:10.1086/339831, Bibcode: 2002AJ....123.2754W.
- ^ a b c d e f g Garrison, R. F. (1994). "A Hierarchy of Standards for the MK Process". Astronomical Society of the Pacific. Bibcode:1994ASPC...60....3G.
- ^ "SIMBAD Object query : CCDM J02319+8915". Centre de Données astronomiques de Strasbourg. Retrieved 2010-06-10.
- ^ "Checking the yellow evolutionary void. Three evolutionary critical Hypergiants: HD 33579, HR 8752 & IRC +10420".
- ^ "On a cosmological timescale, The Earth's period of habitability is nearly over | International Space Fellowship". Spacefellowship.com. Retrieved 2012-05-22.
- ^ a b Stars as Cool as the Human Body
- ^ "Galactic refurbishment". www.spacetelescope.org. ESA/Hubble. Retrieved 29 April 2015.
- ^ Figer, Donald F.; McLean, Ian S.; Najarro, Francisco (1997). "AK‐Band Spectral Atlas of Wolf‐Rayet Stars". The Astrophysical Journal 486: 420. doi:10.1086/304488.
- ^ Bibcode: 1995A&A...295...75K
- ^ Tinkler, C. M.; Lamers, H. J. G. L. M. (2002). "Mass-loss rates of H-rich central stars of planetary nebulae as distance indicators?". Astronomy and Astrophysics 384 (3): 987. doi:10.1051/0004-6361:20020061.
- ^ Miszalski, B.; Crowther, P. A.; De Marco, O.; Köppen, J.; Moffat, A. F. J.; Acker, A.; Hillwig, T. C. (2012). "IC 4663: The first unambiguous \WN] Wolf-Rayet central star of a planetary nebula★". Monthly Notices of the Royal Astronomical Society 423: 934. doi:10.1111/j.1365-2966.2012.20929.x.
- ^ Crowther, P. A.; Walborn, N. R. (2011). "Spectral classification of O2-3.5 If*/WN5-7 stars". Monthly Notices of the Royal Astronomical Society 416 (2): 1311. Bibcode:2011MNRAS.416.1311C. arXiv:1105.4757. doi:10.1111/j.1365-2966.2011.19129.x.
- ^ Outstanding Issues in Our Understanding of L, T, and Y Dwarfs, J. D. Kirkpatrick, April 2007, arXiv:0704.1522. Accessed on line September 18, 2007.
- ^ a b Kirkpatrick, J. Davy; Reid, I. Neill; Liebert, James; Cutri, Roc M.; Nelson, Brant; Beichman, Charles A.; Dahn, Conard C.; Monet, David G.; Gizis, John E.; Skrutskie, Michael F. (July 10, 1999). "Dwarfs Cooler than M: the Definition of Spectral Type L Using Discovery from the 2-µ ALL-SKY Survey (2MASS)". The Astrophysical Journal (The University of Chicago Press) 519 (2): 802–833. Bibcode:1999ApJ...519..802K. doi:10.1086/307414.
- ^ a b Kirkpatrick, J. Davy (2005). "New Spectral Types L and T". Annual Reviews of Astronomy and Astrophysics (Annual Reviews) 43 (1): 195–246. Bibcode:2005ARA&A..43..195K. doi:10.1146/annurev.astro.42.053102.134017.
- ^ Kirkpatrick, J. Davy; Barman, Travis S.; Burgasser, Adam J.; McGovern, Mark R.; McLean, Ian S.; Tinney, Christopher G.; Lowrance, Patrick J. (2006). "Discovery of a Very Young Field L Dwarf, 2MASS J01415823−4633574". The Astrophysical Journal 639 (2): 1120. doi:10.1086/499622.
- ^ Ultra-cool Diminutive Star Weighs In
- ^ LSR 1610-0040: The First Early-Type L Subdwarf, Lépine et al. 2003c
- ^ Discovery of the brightest T dwarf in the northern hemisphere, 2007
- ^ Discovery of the Y1 Dwarf WISE J064723.23-623235.5, J. Davy Kirkpatrick, Michael C. Cushing, Christopher R. Gelino, Charles A. Beichman, C. G. Tinney, Jacqueline K. Faherty, Adam Schneider, Gregory N. Mace, The Astrophysical Journal preprint (submitted 25 Aug 2013)
- ^ Y-Spectral class for Ultra-Cool Dwarfs, N.R.Deacon and N.C.Hambly, 2006
- ^ a b Wehner, Mike (2011-08-24). "NASA spots chilled-out stars cooler than the human body | Technology News Blog – Yahoo! News Canada". Ca.news.yahoo.com. Retrieved 2012-05-22.
- ^ a b NASA spots chilled-out stars cooler than the human body
- ^ NASA'S Wise Mission Discovers Coolest Class of Stars
- ^ The minimum Jeans mass, brown dwarf companion IMF, and predictions for detection of Y-type dwarfs, B. Zuckerman and I. Song, Astronomy and Astrophysics 493, #3 (January 2009), pp. 1149–1154, doi:10.1051/0004-6361:200810038, Bibcode: 2009A&A...493.1149Z.
- ^ a b c Distances, Luminosities, and Temperatures of the Coldest Known Substellar Objects, Trent J. Dupuy and Adam L. Kraus, Science Online (Sept 2013), doi:10.1126/science.1241917
- ^ a b c The Physical Properties of Four ~600 K T Dwarfs, S. K. Leggett et al., The Astrophysical Journal 695, #2 (April 2009), pp. 1517–1526, doi:10.1088/0004-637X/695/2/1517, Bibcode: 2009ApJ...695.1517L.
- ^ CFBDS J005910.90-011401.3: reaching the T-Y brown dwarf transition?, P. Delorme et al., Astronomy and Astrophysics 482, #3 (May 2008), pp. 961–971, doi:10.1051/0004-6361:20079317, Bibcode: 2008A&A...482..961D.
- ^ Exploring the substellar temperature regime down to ~550K, Ben Burningham et al., Monthly Notices of the Royal Astronomical Society 391, #1 (November 2008), pp. 320–333, doi:10.1111/j.1365-2966.2008.13885.x, Bibcode: 2008MNRAS.391..320B; see the abstract.
- ^ European Southern Observatory. "A Very Cool Pair of Brown Dwarfs", 23 March 2011
- ^ Bouigue, R. 1954, Annales d'Astrophysique, Vol. 17, p.104
- ^ Spectral Atlas of Carbon Stars (Barnbaum+ 1996)
- ^ Keenan, P. C. 1954 Astrophysical Journal, vol. 120, p.484
- ^ A Determination of the Local Density of White Dwarf Stars, J. B. Holberg, Terry D. Oswalt and E. M. Sion, The Astrophysical Journal 571, #1 (May 2002), pp. 512–518.
- ^ a b c d A proposed new white dwarf spectral classification system, E. M. Sion, J. L. Greenstein, J. D. Landstreet, J. Liebert, H. L. Shipman, and G. A. Wegner, The Astrophysical Journal 269, #1 (June 1, 1983), pp. 253–257.
- ^ C?rsico, A. H.; Althaus, L. G. (2004). "The rate of period change in pulsating DB-white dwarf stars". Astronomy and Astrophysics 428: 159. doi:10.1051/0004-6361:20041372.
- ^ A Catalog of Spectroscopically Identified White Dwarfs, George P. McCook and Edward M. Sion, The Astrophysical Journal Supplement Series 121, #1 (March 1999), pp. 1–130.
- ^ Digital Demo Room Stellar Structure and Evolution Simulator(date unknown)
- ^ a b "Stars and Habitable Planets". Solstation.com. Retrieved 2012-05-22.
External links
- Libraries of stellar spectra, D. Montes, UCM
- Spectral Types for Hipparcos Catalogue Entries
- Stellar Spectral Classification, Richard O. Gray and Christopher J. Corbally
- Spectral models of stars, P. Coelho
- Merrifield, Michael; Bauer, Amanda; Häußler, Boris (2010). "Star Classification". Sixty Symbols. Brady Haran for the University of Nottingham.


text: Happy Father's Day June 21, 2015 Administrator (0) Happy Father's Day from all of us at Gottlieb & Sons. What Is A Dad?A dad is someone whowants to catch you before you fallbut instead picks you up,brushes you off,and lets you try again. A dad is someone whowants to keep you from making mistakesbut instead lets you find your own way,even though his heart breaks in silencewhen you get hurt. A dad is someone whoholds you when you cry,scolds you when you break the rules,shines with pride when you succeed,and has faith in you even when you fail... - Unknown

subset: commoncrawl


text:
John Tatum Shoot Interview DVD-R
DVD-R Version
Please verify you have a compatible player before purchasing our DVD-R titles. We are not responsible for the compatibility of your player to our DVD-R titles.
Click here to check: (DVD-R Compatibility Chart)
Get ready for a 1980s wrestling superstar from two well remembered, and beloved, promotions; World Class Championship Wrestling and Bill Watts' UWF. Hollywood John Tatum, the man who brought us Hyatt International, sat down with us in the studios to record a very entertaining shoot that goes into great detail on some of the most amazing years, and territories, in recent wrestling history.
Tatum discusses his entire career, including how he met the lovely Missy Hyatt and got his first break with Fritz Von Erichs' World Class. All of the big names of World Class were talked about, including: Chris Adams, Gino Hernandez, Sunshine, Rick Rude, and, of course, the Von Erichs. Tatum even talked to us about the disastrous appearance of cousin Lance Von Erich, which is one World Class memory the entire state of Texas would like to keep buried! You?ll be very surprised to hear Hollywood?s thought on that subject.
It was in Bill Watts fabled UWF that Tatum received the lion?s share of recognition during his career, and in this exclusive interview, John discussed the ins and outs of the promotion while giving his thoughts on all the big angles and wrestlers during his stay with the company. You knew we would have to confront Tatum point blank about what happened between Missy Hyatt and Hot Stuff Eddie Gilbert, and Tatum answered every question we threw at him while giving an amazing recollection of how the events went down so many years ago.
Tatum finished his career after stints in USWA and Global, so John was more than happy to give his thoughts on Memphis? own Jerry Lawler and Bill Dundee while also dishing the dirt on guys like Scott Raven Levy, Mick Foley, and Jerry Lynn. We concluded the interview by getting Tatum?s thoughts on anything and everything in the world of wrestling from the past through today. You wont want to miss this fantastic addition to the RF VIDEO shoot interview series!
Average Customer Review: Not yet rated
Write an online review and share your thoughts with others.


text:
WASHINGTON - The Transportation Security Administration says officers found two throwing daggers hidden in a hollowed-out book at a checkpoint at Reagan-Washington National Airport.
A TSA spokesman says a passenger was stopped Monday when officers found the knives in the person's carry-on bag. The daggers measured just over a half-foot long and were hidden in the hard-cover book.
The passenger was flying to Chicago and surrendered the knives and book.
The TSA has the authority to fine passengers who bring deadly weapons into the airport checkpoint. It was not known if this was done in this case.
A spokesman for the airport did not immediately return a call for comment.


text:
Contest open until Saturday, October 31, 2020
Forms of NatureWednesday, September 30, 2020
You are submitting a new repair request
I've forgotten my password
It's quick and easy to sign up
Complete the form below to create your account
Mandatory data for replying to your request.
We'd love to keep you up to date regarding news, offers and personalised updates from the community. All information on data processing, your rights, objection and analyses can be found here.
*For further information on data processing including behavioral tracking and retention periods as well as your rights regarding the processing of your personal data please refer to our Privacy notice and Cookie policy. If you no longer wish to receive our email-marketing you can withdraw you consent at any time and free of charge by clicking here. You can unsubscribe the newsletter also by clicking on the unsubscribe link at the end of each newsletter. Please note that your withdrawal of consent shall not affect the lawfulness of processing based on your consent before its withdrawal.
All members get access to exclusive benefits:
Inspire, support, challenge each other and get exclusive benefits
Extend your warranty, request repairs and maintenance
Get your free 6 month extended warranty when registering
The latest news, stories and inspiration straight to your inbox


text:
Locked doors: Two witnesses contradict Huguely's alibi
41 commentsLfish April 11th, 2011 | 6:23pm
I hope george hugely rots in hell
along with his mother and father marts sans on fisher who are paying money to have yeardleys name dragged thru mud bc they were too self indulgent to realize the monster they created
god bless you yeardleyNancyDrew April 11th, 2011 | 7:49pm
Correct me if I'm wrong, but - given what we already know about the case the judge saying, you might hear things you " don't want to hear" surprises me, who would expect this to be a walk in the park ?Betty April 11th, 2011 | 8:34pm
Hughley AND his family are MONSTERS!!!jb April 11th, 2011 | 8:41pm
I just hope and pray and hope and pray that Hugheley's family money and "generous donations" will not assist in getting that monster off with a slap on the hand, but frankly, I fear that. He should be delt capitol punishment, and swift.jb April 11th, 2011 | 8:42pm
earlier comment: I intended to say "generous donation to UVA."Fred April 11th, 2011 | 8:43pm
Death penalty fits him wellHolly April 11th, 2011 | 8:44pm
Everyone has the potential to be many things. Blaming parents is not helpful. I hope everyone remembers that our system allows individuals to be innocent until proven guilty. I'm sure that this case has many more elements to be presented.meanwhile April 11th, 2011 | 10:24pm
Holly, if the system assumed him to be innocent, why then has he been in jail since the act was committed?
Yes, I'm sure his lawyers will drag the dead girl's name through the mud, but the evidence is overwhelming. Don't fool yourself.Matt Kessler April 11th, 2011 | 10:41pm
Not the death penalty, but life in prison with no chance of parole. He is a monster and, hopefully, justice will be served despite his parents' money. RIP, Yeardley.John William Duke April 11th, 2011 | 11:19pm
Adderall doe not make a sane person slam one head heads into a wall. And if Georgoe boy is innocent, why did he hot not try and help this young girl, but stole her laptop and then threw it in a dumpster? Too much time for a woman beater being defended for a woman beater being defended and also wasting time the city's time and resources on hearings. There is a gurney awaiting Hughley where he will get an IV. I he gets out, I am sure that there are a lot of others that will that care if him.he gets out anytime soon. ommommy and Daddy can't save him now.John William Duke April 11th, 2011 | 11:22pm
Sorry about my typing. I just think think that this monster and his attorneys should stop playing the game and let him be convicted and then executed very slowlyRestore the Republic April 11th, 2011 | 11:53pm
So far, no one knows both the prosecution's or the defence's side of the equation. Silly comments of the death penalty come from those with little knowledge of law. I suggest a reading of the facts, and as of this point, the public knows not. Educate yourselves.Junius J Johnson III Jr. Esq. April 12th, 2011 | 9:19am
Having money and connections seems to be the thing around Charlottesville. Remember the guy who stabbed the fireman to death on the corner and got off with, what, 1 year or somethig. Then a guy is found innocent of rape and the girl gets $150,000 fro what....lieing? And a poor dumbell gets 5 years for growing weem in the national forest. Justice is determined by $ signs in Charlottesville and thats no justice at all.Old Timer April 12th, 2011 | 9:52am
Your description of justice is hardly unique to the Charlottesville area. Those with money get off, those with political or business connections get off. Everyone else goes to jail. It's like the ranting I see on this site about welfare fraud, yet they are silent by the fraud on Wall Street.reilly April 12th, 2011 | 11:28am
Deleted by moderator.reilly April 12th, 2011 | 1:42pm
perhaps the moderator will like this better...Holly - George already confessed so why should we consider him innocent til proved guilty? He alredy admitted his guilt. Do you even know anything about this case? This is not an episode of Law & Order or CSI Miami, so I can't imagine what hidden truths you are expecting to be unveiled. He had previous incidents and yes, i do know the family and yes this boy should have been dealt with long ago before her violently murdered Yeardly.Gasbag Self Ordained Expert April 12th, 2011 | 3:52pm
It seems like a lot of you, especialy those mentioning the death penalty and life in prison, need to study the murder laws in Virginia. I have sat in on hundreds of murder cases in my lifetime. The best the commonwealth can hope for in this case is a conviction of second degree murder, punishable by confinement in a state correctional facility for not less than five nor more than forty years.
Even though Huguely is currently charged with First degree murder, the commonwealth will most likely not ever be able to prove First dgree beyond a reasonable doubt... namely, " poison, lying in wait, imprisonment, starving, or by any willful, deliberate, and premeditated killing, or in the commission of, or attempt to commit, arson, rape, forcible sodomy, inanimate or animate object sexual penetration, robbery, burglary or abduction".
The Love case also points out the many and troubling inconsistencies in law enforcement in this nation. A black Staunton man has just been indicted on second degree murder for stabbing another black man to death in a domestic argument. The Staunton commonwealth attorney didn't even shoot for First degree murder from the get-go. Why is this? Is a black life not worth as much as that of white life?
I hope Huguely gets whatever he deserves, but reading the death penalty or life imprisonment into this media circus is just plain silly.Susan R April 12th, 2011 | 6:08pm
I wonder if the Hook has the ability to run a tally of costs for this case? Local law enforcement cost and the amount Huguely is paying the lawyers?Gasbag Self Ordained Expert April 12th, 2011 | 7:16pm
Why do costs matter? Both the defendant and the commonwealth are entitled to their day in court. If this trial costs $10 million, they are both still entitled to their day in court.spellchecker April 12th, 2011 | 8:00pm
The Commonwealth brought against Hugueley additional charges of burglary and robbery . A conviction on either charge would lend itself to a greater chance of a conviction on the count of first degree murder as outlined in the Code:
Murder, other than capital murder...or in the commission of, or attempt to commit...robbery, burglary.., is murder of the first degree, punishable as a Class 2 felony.Rich April 12th, 2011 | 8:07pm
Of course he did it - Fry him!!!pittman500 April 12th, 2011 | 8:19pm
If found guilty, he will be charged with 2nd Degree Murder; he did not intentionally go to her apartment to kill her (1st Degree Murder), but in his rage during argument, lost self control and she was killed. His parents have nothing to do with this and the cruel comments about them are unnecessary; I do not blame the parents of some of the posted writers' comments for the writer's ignorance. Just as the tragedy of this killing, having to read about Defense Attorney Fran Lawrence's defense of twisting the facts and fasifying data for the benefit of her client, I pain for Yeardley Love's family as they sit and hear Lawrence's attempt to destroy their daughter in the courtroom and make unbelievable excuses (untruths) for her client - but - in the end, the truth will be exposed during the trial.Gasbag Self Ordained Expert April 12th, 2011 | 8:39pm
spellchecker, the commonwealth will never be able to prove Huguely murdered Miss Love while attempting to burglarize her apartment or while robbing her. It just isn't going to happen in this lifetime. At best, this was nothing more than a domestic dispute that inadvertantly resulted in a homicide. Happens every day in this country. And the media frenzy doesn't make this case any more serious than any other accidental death during domestic violence.
The way the laws are wrttien in Virginia, and punishments thereafter defined, Huguley will most likley not be celebrating his 30th birthday in prison.Restore the Republic April 12th, 2011 | 9:33pm
Huguely's charges: murder, assault, burglary, grand larceny, and robbery.
Murder: The judge I spoke to - before the Commonwealth piled on more charges - said it would be involuntary manslaughter. Felony murder clouds the issue, but up to the Commonwealth to convince a jury. Good luck!
Assault: He said he banged her head against the wall. Possible conviction.
Burglary: He lead them to the laptop. His prints are on it. Possible conviction.
Grand Larceny: Yeah! Prove that laptop was worth more then $200. Possible conviction.
Robbery: This is a hold up, or a stick up. He walks on this one. No conviction.
Jury's are interesting. I agree with Gasbag. He'll see day light on, or before his 30th.
And with the cause of death not 100% provable, the Commonwealth has much work ahead.
I take no sides on this case as my heart goes out to both families for their respective losses. I'm just stating this case is a tough one for the Commonwealth to gain much traction that equals many years for the defendant.Restore the Republic April 12th, 2011 | 10:29pm
The Cav Daily, I believe by far scoops the Hook, with this article: http://www.cavalierdaily.com/2011/04/12/huguely-case-proceeds-to-grand-j...
If the link does not work. Google "Cav Daily".
It seems, of late, the Hook is asleep on reporting.Lfish April 12th, 2011 | 10:46pm
To holly innocence till proven guiltyUnless you admit you banged a petite girls head against a wall saw blood coming from her nose he admu
It's he,s guilty and even if the creature 205 pounds of ugliness didn't mean to kill her well 1 st yr law school the eggshell
Defense is NO defense you get your victim as they are if you se
Trike someone and they have a heart attack guess what you arenguilty of murder 1st degree
And i do vb
Blame parents who are too self indulgent to see a brat bullying a cop saying he was going to kill her ,beating a fellow lacrosse player in his sleep stroll
Strik8sng yeardley at her party 1 week before she died and then paying for his defense and dragging yeardley thru the mud as culpable and coconspirators in her death the mother was a part time asks model accede to press who was divorcing her husband dating and getting re married whilst the father was seeing boy so out of control who jumped off a boat and there is no evicdence that this kid was sent to rehab or punished or given therapy as coconspiratorsLfish April 12th, 2011 | 10:48pm
It's obvious that restore the republic is a friend of the highly connected hugely slutsLfish April 12th, 2011 | 10:50pm
I think they should bang his head against a wall then release him into general public of the va prison system then the spoiled woman abuser will know what it's like to be an abused woman......Md laxer April 12th, 2011 | 10:58pm
you do have to wonder what type of home environment raised such an evil boy
Was the mother absent did she have nannies raise him? The kid seems seriously deranged seriously psychotic
I wonder what his brothers and sisters are like are they crazy too ? Does he have any cousins ? Are they crazy angry and violent ? Is the mother an alcoholic I just heard that her name was mart sans on or mart murphyand a model is she a drug abuser like some models ? It's just so bizarre the whole story he's beating up roomates attacks a female cop he hates woman he must hate his mother too I wonder if he has sisters and he ever attacked them too? Curious ..i think is less wealthy the kid would have already been in jail for violence and arrestsRestore the Republic April 12th, 2011 | 11:01pm
"It's obvious that restore the republic is a friend of the highly connected hugely sluts"
"I think they should bang his head against a wall then release him into general public of the va prison system then the spoiled woman abuser will know what it's like to be an abused woman......"
Lfish, cleary states the obvious stupidity of public input.Restore the Republic April 13th, 2011 | 5:43am
Between my last post on April 12th, 2011 @ 10:29pm and this one, the verbiage reads like a tawdry tirade of a juvenile delinquent. I suppose sometimes parents do not know when their children post inane rants online. The suggestions of violence towards the defendant sounds like henchmen from the Ox Bow Incident. The last sentence of the post on April 12th, 2011 @ 11:01pm reads like Sigmund Freud's psychological projection. Redundant posting further suggests a grade school level conversation where enough repetitions somehow makes one the winner, but for everyone else it just sounds like a myna bird squawking.MIKE PHAUP, RICHMOND,VA April 13th, 2011 | 9:53am
Wait to his cell mate Bubba tells him to bend over?
Yowza..............................................................................Sam April 13th, 2011 | 10:08am
As far as bringing race or money into it, suppose there was a killing in public housing would we be posting (as above):
..I wonder what his brothers and sisters are like are they crazy too ? Does he have any cousins ? Are they crazy angry and violent ? Is the mother an alcoholic..."brian April 13th, 2011 | 12:10pm
He is a bad guy but no first degree murder and lucky to convict on a lessor charge.
Look up mens rea and actus rea to understand. They were both into fighting and arguing
and this time he was drunk and she was mad. She likely set him off and he fought her like
he would a man. Not defending but never a first degree case as this is Chapman trying to
overplay. Remember the stabbing victim at UVa and how he got off. Same will happen here as the guy gets ten years for the lessor charge. Not first degree and not manslaughter so you compromise. Laawrence knows this and is working for that result.Court Square April 13th, 2011 | 2:05pm
In the stabbing victim criminal case the jury took into consideration that both were guys, drunk, and fighting. They can't go there in this. The Civil case it was settled for (withheld) but the former UVa student had filed for bankruptcy and so a few hundred not more than a few thousand was paid. The criminal case will likely put him away for years and a civil case, he will probably file for bankruptcy like the other UVa student did. Even Fred Smith's (Fed Ex chairman's) son didn't have assests in his own name but the 1/2 million verdict against him for punching X (by miracle) got paid.Carolyn April 14th, 2011 | 4:03pm
Money talks...Huguely walks!....mark my word!!! That's the way the justice system works in the good ole USA! I hope and pray I will be proven wrong but I have been around long enough to see that our justice system is deeply flawed!!!walela April 14th, 2011 | 7:17pm
Quote from the article: "Love's mother and sister sat through the at-times grisly testimony, with Huguely's family across the aisle. Huguely had waived his right to be present."
WHAT IS WRONG WITH THIS PICTURE? He had the choice to waive his right to be present? WAIVE HIS RIGHT??? I don't get that. Please, can someone explain to me why he was not required to be there and witness the gory details himself as HER family and friends did?Restore the Republic April 14th, 2011 | 11:57pm
Re: walela
Really, nothing much was served by the defendant being present other than adding to the media circus, doing the perp walk, so being absent was the best play. Nothing legally can be read into this unless going tabloid!
Trial is the place to be present.
Until then: Legal laypersons should park their weak legal verbiage.
At this level the defendant is not useful. Get over it.roadtrip April 15th, 2011 | 10:42am
The Hook says:
"Still, Love died from blunt force trauma, according to medical examiner Bill Gormley, who performed her autopsy and described injuries to her brain, neck, and mouth in detail for two hours."
Two hours worth of testimony and only 1 sentance in this article. This omitted information will be what proves that Hughley murdered Love. Too bad the writer didn't expand on this 2 hours more.
Also, the fact that Love's body was face down and covered up by the comforter and the computer being removed and thrown in the dumpster shows intent to cover up a crime. Hughley lost control and beat her to death. Quite sobering/methodical acts after being drunk all day. His shock over learning of her death shows his absolute denial of reponsibility for his actions.HarryD April 17th, 2011 | 7:04am
7 years, time off for good behavior and time served- out in 5- works for Dad, inherits the biz and lives the life of any priveledged murderer.
"Wait to his cell mate Bubba tells him to bend over?
Talk about blunt force trauma...........very sad April 22nd, 2011 | 8:59am
as far as a i know "high profile lawyers" in this case should be called "the only firm in town that will oppose UVa in court." and puts on bizarre, weak defenses. and, i believe the public record shows, loses most of those cases. and appears to have an unusually close relationship with the lawyers on the other side. Hugely has no case, but there are no independent attorneys in Charlottesville who can or will fight the way our system intended. It is a frightening place. "there will be no police investigation" announced in the first stories. they are above the law and they know it (and have made it that way).


text:
McLEAN, Va. — Virginia's Department of Transportation is launching a study of traffic over the Potomac River bridges.
VDOT says the study spanning several months will also engage Maryland and the District of Columbia, the jurisdictions on the other side of the river from Virginia.
The study will focus on the span of the river from Point of Rocks in the west to the U.S. 301 bridge on the east.
VDOT officials say the study will conclude in the spring and will focus on measuring the problem. It will not recommend any specific solution.
The idea of adding additional spans across the Potomac has been floated for years but typically faces strong opposition from homeowners who fear the traffic impact another bridge would cause.


text:
Tweet from the Command Line with Twidge
Graphical Twitter clients are a dime a dozen these days, but what if you want to use the ubiquitous micro-blogging service from the terminal? On machines like Linutop or netbooks, running a graphical Twitter client is a waste of precious resources, so a command-line tool like Twidge can come in rather handy. Using it, you can quickly post tweets and view the latest posts from people you follow without leaving the convenience of the terminal. Moreover, Twidge supports Identi.ca — an open source micro-blogging service.


text: Dave's ESL Cafe's Student Discussion Forums :: View topic - Language School Awards - The Best Schools of 2007 Dave's ESL Cafe's Student Discussion Forums"The Internet's Meeting Place for ESL/EFL Students and Teachers from Around the World!" FAQ Search Memberlist Usergroups Register Profile Log in to check your private messages Log in Language School Awards - The Best Schools of 2007 Dave's ESL Cafe's Student Discussion Forums Forum Index -> English Schools View previous topic :: View next topic Author Message worldclassJoined: 22 Jun 2006Posts: 36 Posted: Tue Jan 01, 2008 1:21 am Post subject: Language School Awards - The Best Schools of 2007 Language Travel magazine recently held their annual 'Star Awards' ceremony in London. Every year, language travel agents from around the world nominate language schools for the awards based on the level of student satisfaction and the level of service offered to agents. For international students looking for high quality language programs in a market cluttered by so many schools, enrolling with a Star Award school is a great way to guarantee that they have found a school that offers the highest standard of service, an excellent academic program and great value. The agents voting for the 'Star Schools' enrol anywhere between 20 and 10,000 students in educational programs abroad every year. They are constantly in contact with these schools and receiving feedback from students so they therefore have an excellent knowledge of which language course providers are the best. 'Star Awards' nominees and winners include the following schools- LTM Star English Language School - Europe: Centre for English Studies, Ireland and UK. Other Nominees: EAC, UK Intuition Languages, UK Atlantic Language Galway, Ireland LTM Star English Language School - North America: Ilac - International Language Academy of Canada, Toronto, Canada. Other Nominees: Study English in Canada, Toronto, ONT. Pacific Language Institute, Vancouver, BC. Language Studies Canada,Toronto, ONT. LTM Star French language school: France Langue, Paris. Other Nominees: Accord, Paris. French in Normandy, Le Petit Quevilly. Institut Linguistique Adenet, Montpellier. LTM Star Spanish language school: Malaca Instituto, Malaga, Spain. Other Nominees: Babylon Idiomas, Barcelona (also in Madrid, Valencia and Seville). Jakera Tours, Merida, Venezuela. International House Sevilla CLIC, Seville. LTM Star Italian language school: Dilit International House, Rome. Other Nominees: Linguaviva, Florence. Scuola Leonardo da Vinci, Florence. Societa Dante Alighieri, Sienna. LTM Star German language school: did deutsch institut, nationwide. Other Nominees: GLS Sprachenzentrum, Berlin. Humboldt Institut, Argenbuehl. IH Prolog, Berlin. LTM Star English Language School - southern hemisphere: English Language Company, Sydney, Australia. Other Nominees: Good Hope Studies, Cape Town, South Africa. Cape Studies, Cape Town, South Africa. Languages International, Auckland, New Zealand. A list of all the Star Awards winners can be found on the LTM website here._________________www.LanguageSchoolSecrets.com - How to find the best schools and save money on your booking. Back to top BLKDRGNJoined: 23 Dec 2009Posts: 5Location: Canada Posted: Sun May 02, 2010 1:28 pm Post subject: ESL Schools and Awards I don't wish to sound negative here, merely informative, but here's my considered professional opinion as a teacher who has worked at numerous ESL schools around the world. Contrary to what the poster asserts, choosing an English school because it has won some sort of industry award, is no "guarantee" of high quality. The problem with such an assertion is that the organizations that bestow such awards tend not to be non-profit organizations; so, there may be a lack of true independence. Secondly, it is natural to expect that these awards would tend to select bigger schools, at least because they have more awareness in the minds of voting members. The reality is, however, that smaller and therefore less bureaucratic schools often can provide more personal attention to their students. Back to top longshikongJoined: 14 Jan 2012Posts: 30 Posted: Fri Jan 20, 2012 4:49 am Post subject: Re: ESL Schools and Awards BLKDRGN wrote: I don't wish to sound negative here, merely informative, ... You might be right but then why aren't the larger schools represented? Here's the 2011 results: http://hothousemedia.com/ltm/star.htm Back to top AfraJoined: 10 Jul 2013Posts: 131 Posted: Tue Sep 24, 2013 6:15 am Post subject: Did you know ILAC is the most awarded English School in Canada? Year after year students and agents from around the world consistently vote ILAC as the #1 English Language School in the country. ILAC is honoured to be recognized for our excellent programs, quality of teaching and dedication to customer service. We are very proud of our numerous awards and continuously strive to provide the best experience for international students who come to study and learn English in Toronto and Vancouver. We thank all our partners for their support, and we especially thank our students for choosing to make us a part of their English Language Experience. Voted #1 English Language School in Canada Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First Dave's ESL Cafe's Student Discussion Forums Forum Index -> English Schools All times are GMT - 8 Hours Page 1 of 1 Jump to: Select a forum Student Forums----------------ComputersCurrent NewsCultureEnglish SchoolsFamilyFilm and CinemaFoodHealth and FitnessHelp CenterHobbiesHolidaysLearning EnglishLiteratureMaking FriendsMusicOpinionsPetsScienceSportsThe Strange and MysteriousTOEFL and Other English ExamsTravel You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot vote in polls in this forum Dave's ESL Cafe is maintained by the one and only Dave Sperling. Banner Advertising | Bookstore / Alta Books | FAQs | Articles | Interview with Dave Copyright © 2018 Dave's ESL Cafe | All Rights Reserved | Contact Dave's ESL Cafe | Site Map Teachers College, Columbia University: Train to Teach English Here or Abroad Powered by phpBB © 2001, 2002 phpBB Group


text:
E-Hawks Blank St. Edmonds, Face IKM Friday
Emmetsburg's second step down the postseason trail came at the expense of Fort Dodge St. Edmonds on Monday night, as the E-Hawks posted a 28-0 shutout over the Gaels. The win moves Emmetsburg into a Class 1A Quarterfinal matchup this Friday, Nov. 2, against IKM-Manning at Manning at 7 p.m. for the right to advance to a semi-final game at the UNI Dome in Cedar Falls on Saturday, Nov.10.
For the first seven minutes of Monday's game, it was an exercise in defense for both teams, with exchanges of punts back and forth.But after the Gaels second punt of the contest, Emmetsburg got the ball at their own 20 after a touchback.
After a first down run of seven yards by Andrew Wellik, on second down, quarterback Jake Jackson handed off to the senior again. Wellik threaded his way through the Gael defense, shook off at least two tackle attempts and outran the Gaels 73 yards for the opening score of the game with 4:56 to go in the quarter. The conversion kick by Nick Merwald went wide, making the score 6-0.
St. Eds would get the ball at their own 32 yard line and began moving the ball, but Jake Jackson stepped up and intercepted a pass at the E-Hawk 44 yard line to kill the drive and end the first quarter with a 6-0 lead for the E-Hawks.
Emmetsburg would drive to the Gaels' 26 yard line but stalled out, prompting a 40-yard field goal attempt by Nick Merwald, but the kick fell short.
St. Eds would take over at the 20 and tried to mount a drive, getting to their own 28, only to fumble the ball, which Tyler Henson fell on for the E-Hawks at the Gaels' 28 yard stripe with 11:17 to go in the half.
Using the turnover to their advantage, Jackson handed off to Wellik who broke to the one yard line, and then dived into the end zone on the next play for the touchdown with 10:43 to play. The E-Hawks went for two on the conversion and Wellik raced in to score, only to be hit by the Gaels' Landon Peed after the play was over, drawing a late-hit penalty on the resulting kickoff against the Gaels.
With a 14-0 advantage, the E-Hawk defense would hold the Gaels to a first down and then a punt, getting the ball back. But Emmetsburg's drive would stall out and result in a punt.
As St. Eds took over at their own 13, quarterback David Flattery went to the air, only to be picked off by Nick Schany, but a pass interference call on the E-Hawks negated the pick. A first down from the penalty would go backwards for the Gaels, as Taylor Wegner dropped Flattery for an eight-yard loss and prompted another punt to end the half with Emmetsburg leading 14-0.
Emmetsburg would kick off to the Gaels to start the second half and the defense settled in, as the two clubs would once again exchanged possessions and punts through the third frame, with the E-Hawks getting the ball to the Gaels' 34 yard line to end the quarter.
Holding the 14-0 lead to start the final frame, Emmetsburg wasted little time in scoring again, as Wellik would run 38 yards on the second play of the quarter to score with 11:23 to go in the contest. Nick Merwald added the kick for a 21-0 lead and some breathing room for the E-Hawks.
St. Edmonds would take over and go three and out, giving Emmetsburg the ball on their own four yard line. A nice nine-yard run on first down by Cody Henderson gave the E-Hawks room to work just inside their 14 yard line.
On second and one, Wellik tucked the ball in and took off for the opposite end of the field, once again breaking at least three tackle attempts and outrunning two defenders for an 86-yard touchdown juant with 8:55 to go in the contest. Merwald added the kick for a 28-0 score that all but put the game on ice.
The Gaels would get the ball back on the kick and started moving against the E-Hawks, but with 4:33 to go in the game, Jake Jackson played the spoiler role once again, picking off a Flattery pass at the E-Hawk 30 and returning it to the Gaels' 46 yard line.
Emmetsburg would end up punting the ball after the pick, and the Gaels started upfield again, only to be picked off again by Nick Schany with :23 to go, ending the ballgame with the shutout for the E-Hawks.
Emmetsburg would rack up a total offense of 404 yards while St. Edmonds managed to gain 116 yards rushing and 26 yards passing as they completed four of nine with three interceptions.
Andrew Wellik ran wild in the win for Emmetsburg with 31 carries for 365 yards, including four touchdown runs of 73, one, 38 and 89 yards. Cody Henderson added nine carries for 46 yards, with Allen Jensen rushing three times for eight yards. Jake Jackson would rush four times for eight yards and Austin McCartan had a three yard rushing attempt.
Jake Jackson attempted just one pass in the contest which fell incomplete.
On the defensive side of the ball, Mitch Petersen had 16 tackles, while Tanner Dahm added 15 stops and Austin McCartan made 13 tackles.
Nick Schany made eight tackles and an interception, while Tayler Wegner had seven tackles and a sack. Jackson had two interceptions and Tyler Henson added a fumble recovery to the winning effort for the E-Hawks, who improved to 10-1 on the season with the victory.


text:
Wikipedia flush with funds, short on volunteers
By online business reporter Michael Janda
One of the internet's most ubiquitous sites, Wikipedia, is facing a shortage of new volunteers that threatens its future growth.
The not-for-profit Wikimedia Foundation, which runs Wikipedia and its related sites, says its group of web pages is the fifth most visited in the world, accessed by around half-a-billion people last year.
Wikimedia says it is the only not-for-profit running a top 40 global website, so you would think money would be its biggest problem.
However, the foundation's 2011-12 financial report shows it received donations and contributions of more than $US35 million, with almost another million worth of donated equipment.
Its total cash expenditure was around $US27 million, leaving it a handy surplus.
Wikimedia's executive director Sue Gardner, in Australia for a speaking tour, says Wikimedia is now pulling in around $US40 million a year in donations from its users, up from around a million when she joined the organisation in 2007.
She says donations have kept pouring in, despite the world's economic problems.
"I actually think that charities tend to exaggerate the effects of those kinds of economic crisis on their revenues," she told ABC News Online.
"People can be finding themselves really in desperate circumstances, but that's a small proportion of the population, most people are belt tightening a little bit in hard times and they're not going to cut out small charitable contributions that matter to them, because frankly it feels good to give to charity."
Volunteer decline
Instead, Sue Gardner says it is a fall in the number of new people volunteering to edit articles and administer the site that is the biggest concern.
"We don't know how serious of a concern that should be," she said.
"There's a school of thought which suggests that after you've written the article about Saturn and accounting and France, that you don't need as many editors as you used to - once you have a solid base of articles inside Wikipedia, really at that point you're just making small improvements and you're just keeping things up to date.
"I don't know if that's true or not - when I read Wikipedia I find lots missing and I think that there's lots of new material that wants to be added to Wikipedia that's not there yet."
Sue Gardner says the foundation's ultimate goal would be for everyone to be a Wikipedia editor, to meet its aim to be repository for the sum of human knowledge.
While that holy grail is likely unachievable, she says the foundation is working to make Wikipedia easier to edit for non-geeks.
"It's a little too hard to contribute right now... you have to learn Wiki syntax, which is not hard to learn but it takes a little time," she observed.
"We're rolling out what we call the visual editor this [northern hemisphere] summer, and that's going to make it significantly easier to edit... and so, at that point, we expect that one of the big impediments will come down and we'll be able to have a more generalist editor base."
Wikipedia is also recruiting new editors through partnerships with universities, where lecturers give students a page to write or update as part of their coursework.
Developing nation push
The major new frontier for the foundation is an effort to give more people in developing countries access to Wikipedia, particularly those whose only access to the worldwide web is through their mobile phone.
It is doing this by partnering with mobile phone providers who agree to waive the data charges for visiting Wikipedia's mobile site on their networks.
However, Wikipedia says the arrangements are non-exclusive and non-commercial, with no money changing hands and the Wikipedia site remaining ad free.
"I think that they [the phone companies] feel like it's a service to their subscribers and so maybe their subscriber would be more likely to go with them as a provider than some alternative company that doesn't offer that," Sue Gardner explained.
"They want to be understood to be a good, responsible corporate citizen, and probably a little bit of it may not be entirely rational, but I think they like Wikipedia too."
You can listen to the full interview with Sue Gardner here, where she also discusses Wikipedia's competition, the reliability of its information, and how fingertip access to facts and figures is changing the way we think.


text:
Product Description
- This Item Is NEW!
- This Is A True Kenmore Part!
- Don't See Your Model Number? Send Us A Message!
This refrigerator door shelf bar is for the RIGHT hand door (when looking into the refrigerator). This original Kenmore Refrigerator Door Shelf Bar originally shipped with the following Kenmore devices: 106.5175471, 106.5175971, 106.5179241 This is a true Kenmore part! This item is NEW! Don't see your model number? Send us a message as we are happy to help!
FREE shipping within the USA
Have a Question?
Be the first to ask a question about this.


text:
The Assabet Valley Regional Technical High School football team drew the fourth seed in this year's Division 6 playoffs, and will face top-seeded Blackstone Valley Tech on Tuesday night, at Foley Stadium, in Worcester.
Kickoff will be at 5:15 p.m.
Assabet enters the game with a 7-4 record, while Blackstone Valley is 10-1.
Second-seeded Bay Path (10-1) meets third-seeded Littleton (8-3) in the other playoff semifinal. The winners of the two games will clash in the Division 6 Super Bowl on Saturday.