temperature of the surface of the sun in kelvin
approximately 5,778 K
361635
the Sun is actually emitting more photons in the green portion of the spectrum than any other. When the Sun is low in the sky, atmospheric scattering renders the Sun yellow, red, orange, or magenta. Despite its typical whiteness, most people mentally picture the Sun as yellow; the reasons for this are the subject of debate. The Sun is a G2V star, with "G2" indicating its surface temperature of approximately 5,778 K (5,505 °C, 9,941 °F), and "V" that it, like most stars, is a main-sequence star. The average luminance of the Sun is about 1.88 giga candela per square
Sun
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thousand Kelvin. Its density is 5500 kg/m which is not much different from Earth. Kepler-70b is likely a rocky exoplanet with a mass of 0.44 and a radius of 0.76 . It has a surface temperature of several thousand Kelvin, one of the hottest known surface temperatures on any exoplanet. While the precise temperature is not known, it is expected to be hotter than the surface of the Sun. The exoplanet has an orbit period shorter than any exoplanet known to date, with an orbital period of 5.76 hours (345 minutes). This comes in second to the exoplanet PSR 1719-14
Kepler-70b
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materials, the emissivity in the visible spectrum is similar to the emissivity in the infrared spectrum; however there are exceptions, notably certain metal oxides that are used as "selective surfaces". In a vacuum or in outer space, there is no convective heat transfer, thus in these environments, radiation is the only factor governing heat flow between the heat sink and the environment. For a satellite in space, a 100 °C (373 Kelvin) surface facing the Sun will absorb a lot of radiant heat, because the Sun's surface temperature is nearly 6000 Kelvin, whereas the same surface facing deep-space will radiate
Heat sink
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temperature of light sources. Colour temperature is based upon the principle that a black body radiator emits light whose colour depends on the temperature of the radiator. Black bodies with temperatures below about appear reddish, whereas those above about appear bluish. Colour temperature is important in the fields of image projection and photography, where a colour temperature of approximately is required to match "daylight" film emulsions. In astronomy, the stellar classification of stars and their place on the Hertzsprung–Russell diagram are based, in part, upon their surface temperature, known as effective temperature. The photosphere of the Sun, for instance, has
Kelvin
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it would take for the near-surface to cool to its present temperature. His calculations did not account for heat produced via radioactive decay (a process then unknown to science) or, more significantly, convection inside the Earth, which allows more heat to escape from the interior to warm rocks near the surface. Even more constraining were Kelvin's estimates of the age of the Sun, which were based on estimates of its thermal output and a theory that the Sun obtains its energy from gravitational collapse; Kelvin estimated that the Sun is about 20 million years old. Geologists such as Charles Lyell
Age of the Earth
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effective temperature of 15000 Kelvin, an absolute magnitude of -1.02 and a mass of 5.9 solar masses. It is located 165.1 pc (538.5 light years) from the Sun. Zeta Chamaeleontis Zeta Chamaeleontis, Latinized from ζ Chamaeleontis, is a star located in the constellation Chamaeleon. Located around 570 light-years distant, it shines with a luminosity approximately 522 times that of the Sun and has a surface temperature of 13,544 K. South African Astronomer A.W.J. Cousins noted it to vary between magnitudes 5.06 and 5.17 in 1960. It was classified as a Beta Cephei variable in the Hipparcos and Tycho Catalogues (ESA
Zeta Chamaeleontis
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of around 20 grams per m per 5 K. Around 1 kilojoules of energy is needed to heat 1 kilogram of dry air by one kelvin (see heat capacity). So, to increase the temperature of 1 m of air (at sea level and at 15 °C) 5 °C requires around 5 °C * 1 kilojoules/(kilogram*kelvin) * 1.225 kilograms = 6.125 kilojoules. By doing so, you've reduced the mass of 1 m of air by around 24 grams. On a clear day with a black body surface of 1 m perpendicular to the sun and no heat loss, this would take
Solar balloon
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the gaps between them. It is possible that the nuclei at the surface are iron, due to iron's high binding energy per nucleon. It is also possible that heavy elements, such as iron, simply sink beneath the surface, leaving only light nuclei like helium and hydrogen. If the surface temperature exceeds 10 kelvin (as in the case of a young pulsar), the surface should be fluid instead of the solid phase that might exist in cooler neutron stars (temperature <10 kelvin). The "atmosphere" of a neutron star is hypothesized to be at most several micrometers thick, and its dynamics are
Neutron star
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parallax of 66.50 ± 0.11 mas yielding a distance of 15 parsecs or approximately 49 light years from Earth. Given a surface temperature of 7,740 Kelvin, stellar models yield a total luminosity for the star of about 17 times the luminosity of the Sun. Alderamin has a radius of 2.3 times the Sun's radius and boasting a mass that is 1.74 that of the Sun. Like other stars in its class, it is slightly variable with a range in brightness of 0.06 magnitude, and is listed as a Delta Scuti variable. Alderamin has a very high rotation speed of at
Alpha Cephei
2389891
Deneb appears to have a diameter of about over 200 times that of the Sun; if placed at the center of the Solar System, Deneb would extend out to the orbit of the Earth. It is one of the largest known white stars. Deneb is a bluish-white star of spectral type A2Ia, with a surface temperature of 8,500 kelvin. Since 1943, its spectrum has served as one of the stable references by which other stars are classified. It is the prototype of a class of variable stars known as Alpha Cygni variables. Its surface undergoes non-radial fluctuations which cause its
Deneb
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the process as "evaporation" by analogy to the more familiar process with water. Likewise, if the amount of heat being applied to coronal material is slightly reduced, the material very rapidly cools down past the temperature catastrophe to around one hundred thousand kelvin, and is said to have "condensed". The transition region consists of material at or around this temperature catastrophe. The transition region is visible in far-ultraviolet (FUV) images from the TRACE spacecraft, as a faint nimbus above the dark (in FUV) surface of the Sun and the corona. The nimbus also surrounds FUV-dark features such as solar prominences,
Solar transition region
364488
equivalence relationship "E" = "mc". The hydrogen fusion process is temperature-sensitive, so a moderate increase in the core temperature will result in a significant increase in the fusion rate. As a result, the core temperature of main sequence stars only varies from 4 million kelvin for a small M-class star to 40 million kelvin for a massive O-class star. In the Sun, with a 10-million-kelvin core, hydrogen fuses to form helium in the proton–proton chain reaction: These reactions result in the overall reaction: where e is a positron, γ is a gamma ray photon, ν is a neutrino, and H
Star
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of a stellar black hole is about . The temperature inside a newly formed neutron star is from around 10 to 10 kelvin. However, the huge number of neutrinos it emits carry away so much energy that the temperature of an isolated neutron star falls within a few years to around 10 kelvin. At this lower temperature, most of the light generated by a neutron star is in X-rays. Neutron stars have overall densities of to ( to times the density of the Sun), which is comparable to the approximate density of an atomic nucleus of . The neutron star's
Neutron star
17040652
surface temperature ranging from 2200 to 2700 Kelvin. A giant star, its diameter is 400 times that of the sun, and if placed at the center of the Solar System would stretch out to 30% further than Mars' orbit. Its absolute magnitude is −2.0. X Trianguli Australis X Trianguli Australis is a star in the southern constellation Triangulum Australe. It is a red-hued carbon star with an average apparent magnitude of +5.89. It is approximately 1173 light years (360 parsecs) from Earth, though this could vary by up to 200 light years. It is a semi-regular variable star with two
X Trianguli Australis
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class G5V-G6V; it is 66 percent larger and 22 percent more massive than the Sun, and is 413 light-years away. The effective temperature of the star is 5609 Kelvin, and considering that HD 89345 b makes one revolution around the star in 11.8 days, being from it at a distance of 0.11 astronomical unit, This planet was described by researchers as a warm subterranean with an equilibrium temperature of 1059 Kelvin. HD 89345 b, the Saturn-sized exoplanet orbiting a slightly evolved star HD 89345, was discovered in 2018 using the transit photometry method, the process in which detects distant planets
HD 89345 b
13405820
contact with the surface. NMR Cryoporometry (NMRC) is a recent technique for measuring total porosity and pore size distributions. It makes use of the Gibbs-Thomson effect : small crystals of a liquid in the pores melt at a lower temperature than the bulk liquid : The melting point depression is inversely proportional to the pore size. The technique is closely related to that of the use of gas adsorption to measure pore sizes (Kelvin equation). Both techniques are particular cases of the Gibbs Equations (Josiah Willard Gibbs): the Kelvin Equation is the constant temperature case, and the Gibbs-Thomson Equation is
Nuclear magnetic resonance in porous media
12750522
the saturation vapor pressure (P < P) inside a capillary. At the heart of the Kelvin equation is the pressure difference between the liquid and vapor phases, which comes as a contrast to traditional phase diagrams where phase equilibrium occurs at a single pressure, known as P, for a given temperature. This pressure drop (formula_9) is due solely to the liquid/vapor surface tension and curvature of the meniscus, as described in the Young-Laplace equation. <br> In the Kelvin equation, the saturation vapor pressure, surface tension, and molar volume are all inherent properties of the species at equilibrium and are considered
Capillary condensation
635581
whole surface of the earth is at one temperature. Another interesting question is to ask what the temperature of a blackbody surface on the earth would be assuming that it reaches equilibrium with the sunlight falling on it. This of course depends on the angle of the sun on the surface and on how much air the sunlight has gone through. When the sun is at the zenith and the surface is horizontal, the irradiance can be as high as 1120 W/m. The Stefan–Boltzmann law then gives a temperature of or 102 °C. (Above the atmosphere, the result is even
Stefan–Boltzmann law
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Kelvin The Kelvin scale is an absolute thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics. The kelvin (symbol: K) is the base unit of temperature in the International System of Units (SI). Until 2018, the kelvin was defined as the fraction of the thermodynamic temperature of the triple point of water (exactly 0.01 °C or 32.018 °F). In other words, it is defined such that the triple point of water is exactly 273.16 K. On 16 November 2018, a new definition was adopted, in
Kelvin
19569413
having a mass of 1.22 , a radius of 1.79 , and a surface temperature of 6210 ± 100 K. The secondary star (Kepler-1647 B), on the other hand, has a mass of 0.975 , a radius of 1.79 , and a surface temperature of 5770 K. In comparison, the Sun has a surface temperature of 5778 K. The binary star system's age is estimated to be about 4.4 billion years old, about 200 million years younger than the Sun. Kepler-1647b is in the habitable zone of the star system. Since the planet is a gas giant, it is unlikely
Kepler-1647b
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Kelvin–Helmholtz mechanism The Kelvin–Helmholtz mechanism is an astronomical process that occurs when the surface of a star or a planet cools. The cooling causes the pressure to drop, and the star or planet shrinks as a result. This compression, in turn, heats the core of the star/planet. This mechanism is evident on Jupiter and Saturn and on brown dwarfs whose central temperatures are not high enough to undergo nuclear fusion. It is estimated that Jupiter radiates more energy through this mechanism than it receives from the Sun, but Saturn might not. The latter process causes Jupiter to shrink at a
Kelvin–Helmholtz mechanism
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been constant): where formula_6 is the luminosity of the Sun. While giving enough power for considerably longer than many other physical methods, such as chemical energy, this value was clearly still not long enough due to geological and biological evidence that the Earth was billions of years old. It was eventually discovered that thermonuclear energy was responsible for the power output and long lifetimes of stars. Kelvin–Helmholtz mechanism The Kelvin–Helmholtz mechanism is an astronomical process that occurs when the surface of a star or a planet cools. The cooling causes the pressure to drop, and the star or planet shrinks
Kelvin–Helmholtz mechanism
18918022
the planet would be thick and misty, covering much of the surface as viewed from space. The planet takes 385 Earth days to orbit its star. Its radius is 50% bigger than Earth's, and lies within the conservative habitable zone of its parent star. It has an equilibrium temperature of , a little warmer than Earth. The host star, Kepler-452, is a G-type star that is about the same mass of the Sun, only 3.7% more massive and 11% larger. It has a surface temperature of 5757 K, nearly the same as the Sun, which has a surface temperature of
Kepler-452b
5206696
suggest the luminous blue variable phase takes place during the latest phases of core hydrogen burning (LBV with high surface temperature), the hydrogen shell burning phase (LBV with lower surface temperature), and the earliest part of the core helium burning phase (LBV with high surface temperature again) before transitioning to the Wolf–Rayet phase, thus being analogous to the red giant and red supergiant phases of less massive stars. There appear to be two groups of LBVs, one with luminosities above 630,000 times the Sun and the other with luminosities below 400,000 times the Sun, although this is disputed in more-recent
Luminous blue variable
19584879
hot Jupiter. The host star, V830 Tauri, is a T Tauri star that is the same mass of the Sun, but twice the radius. It has a surface temperature of 4250 ± 50 K. In comparison, the Sun has a surface temperature of 5778 K. The star's age is estimated to be about 2 million years old, which makes it a very young star. For comparison, the Sun is 4.6 billion years old. The star has not yet fully contracted to become a main sequence star, which ties in with its bloated radius but similar mass to the Sun. Given
V830 Tauri b
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Temperature Temperature is a physical quantity expressing hot and cold. It is measured with a thermometer calibrated in one or more temperature scales. The most commonly used scales are the Celsius scale (formerly called "centigrade") (denoted °C), Fahrenheit scale (denoted °F), and Kelvin scale (denoted K). The kelvin (spelled with a lower-case k) is the unit of temperature in the International System of Units (abbreviated SI), in which temperature is one of the seven fundamental base quantities. The Kelvin scale is widely used in science and technology. Theoretically, the coldest a system can be is when its temperature is absolute
Temperature
4127484
temperature: (Measurement of temperature) "Degrees Kelvin" (K) is a former name for the SI unit of temperature on the thermodynamic (absolute) temperature scale. Since 1967 it has been known simply as the kelvin, with symbol K (without a degree symbol). Degree absolute (°A) is obsolete terminology, often referring specifically to the kelvin but sometimes the degree Rankine as well. Degree (temperature) The term degree is used in several scales of temperature. The symbol ° is usually used, followed by the initial letter of the unit, for example “°C” for degree(s) Celsius. A degree can be defined as a set change
Degree (temperature)
1423793
processes are: Waves or oscillations, lose energy over time, typically from friction or turbulence. In many cases, the "lost" energy raises the temperature of the system. For example, a wave that loses amplitude is said to dissipate. The precise nature of the effects depends on the nature of the wave: an atmospheric wave, for instance, may dissipate close to the surface due to friction with the land mass, and at higher levels due to radiative cooling. The concept of dissipation was introduced in the field of thermodynamics by William Thomson (Lord Kelvin) in 1852. Lord Kelvin deduced that a subset
Dissipation
4464566
break-even. However, the temperature was far below what would be required. In July 1986, TFTR achieved a plasma temperature of 200 million kelvin (200 MK), at that time the highest ever reached in a laboratory. The temperature is 10 times greater than the center of the sun, and more than enough for breakeven. However, to reach these temperatures the triple product had been greatly reduced to , two or three times too small for break-even. Major efforts to reach the conditions needed for break-even continued. Donald Grove, TFTR project manager, said they expected to achieve that goal in 1987. This
Tokamak Fusion Test Reactor
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Evapoporometry Evapoporometry is a method used to determine pore-size in synthetic membranes. Based on the kelvin equation, this technique is most accurate for detection of pore diameters between 4 nm to 150 nm. Evapoporometry uses modified forms of the kelvin equation to relate the evaporation of a wetting liquid (usually 2-propanol) from a membrane to the average diameter of the pores in that membrane. The primary equation used in this technique is: formula_1 Where formula_2 is the pore diameter, formula_3 is the surface tension, formula_4 is the vapor molar volume, formula_5 is the gas constant, formula_6 is the absolute temperature,
Evapoporometry
43150
0.14 solar masses (), and a radius 15% to 20% of that of the Sun. Thus, although Barnard's Star has roughly 150 times the mass of Jupiter (), its radius is only 1.5 to 2.0 times larger, due to its much higher density. Its effective temperature is 3,100 kelvin, and it has a visual luminosity of 0.0004 solar luminosities. Barnard's Star is so faint that if it were at the same distance from Earth as the Sun is, it would appear only 100 times brighter than a full moon, comparable to the brightness of the Sun at 80 astronomical units.
Barnard's Star
548758
Indi Ba and Bb, a pair of brown dwarfs gravitationally bound to a Sun-like star 12 light-years from the Sun, and Luhman 16, a binary system of brown dwarfs at 6.5 light-years from the Sun. The standard mechanism for star birth is through the gravitational collapse of a cold interstellar cloud of gas and dust. As the cloud contracts it heats due to the Kelvin–Helmholtz mechanism. Early in the process the contracting gas quickly radiates away much of the energy, allowing the collapse to continue. Eventually, the central region becomes sufficiently dense to trap radiation. Consequently, the central temperature and
Brown dwarf
19720337
from the Sun. Iota Normae is an B-type main-sequence star with a stellar classification of B9.5 V. It is larger than the Sun with 2.6 times the mass of the Sun and about 3.1 times the Sun's radius. The star is estimated to be 257 million years old and is spinning with a projected rotational velocity of 111 km/s. It is radiating approximately 40 times the Sun's luminosity from its photosphere at an effective temperature of 10,593 Kelvin. Iota2 Normae ι Normae, Latinised as Iota Normae, is a single, blue-white star located in the southern constellation of Norma. It is
Iota2 Normae
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its giant host star. Nevertheless, when Aldebaran was a main sequence star, it is likely that the planet had an equilibrium temperature comparable to that of the Earth. The host star, Aldebaran, is an orange giant star, meaning it has moved off from the main sequence and exhausted the supply of hydrogen in the core. It has a spectral class of K5 III. Aldebaran is a K-type star that is 1.16 ± 0.07 times the mass and 44 times the radius of the Sun. It has a surface temperature of 3,910 K. In comparison, the Sun has a surface temperature
Aldebaran b
5100960
enhance concentration in offices. CCT dimming for LED technology is regarded as a difficult task, since binning, age and temperature drift effects of LEDs change the actual color value output. Here feedback loop systems are used for example with color sensors, to actively monitor and control the color output of multiple color mixing LEDs. The color temperature of the electromagnetic radiation emitted from an ideal black body is defined as its surface temperature in kelvins, or alternatively in "mireds" (micro-reciprocal kelvin). This permits the definition of a standard by which light sources are compared. To the extent that a hot
Architectural lighting design
12736265
star named Beta Pictoris. The star has a mass of 1.75 and a radius of 1.8 . It has a surface temperature of 8056 K and is 12 million years old. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K. It is slightly metal-rich, with a metallicity ([Fe/H]) of 0.06, or 112% of that found in the Sun. Its luminosity () is 8.7 times that of the Sun. The star's apparent magnitude, or how bright it appears from Earth's perspective, is 3. Therefore, it can be seen with the naked eye.
Beta Pictoris b
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freezing point / melting point that is inversely proportional to the pore size, as given by the Gibbs–Thomson equation. The technique is closely related to using gas adsorption to measure pore sizes, but uses the Gibbs–Thomson equation rather than the Kelvin equation. They are both particular cases of the Gibbs Equations of Josiah Willard Gibbs: the Kelvin equation is the constant temperature case, and the Gibbs–Thomson equation is the constant pressure case. This behaviour is closely related to the capillary effect and both are due to the change in bulk free energy caused by the curvature of an interfacial surface
Gibbs–Thomson equation
361657
visible from Earth's surface, but is readily observable from space by instruments sensitive to the extreme ultraviolet portion of the spectrum. The corona is the next layer of the Sun. The low corona, near the surface of the Sun, has a particle density around 10 m to 10 m. The average temperature of the corona and solar wind is about 1,000,000–2,000,000 K; however, in the hottest regions it is 8,000,000–20,000,000 K. Although no complete theory yet exists to account for the temperature of the corona, at least some of its heat is known to be from magnetic reconnection. The corona
Sun
506407
certain wavelengths. The surface of a star is defined to have a temperature given by the effective temperature in the Stefan–Boltzmann law. Stars, except neutron stars, have no solid surface. Therefore, the photosphere is typically used to describe the Sun's or another star's visual surface . The Sun is composed primarily of the chemical elements hydrogen and helium; they account for 74.9% and 23.8% of the mass of the Sun in the photosphere, respectively. All heavier elements, called metals in astronomy, account for less than 2% of the mass, with oxygen (roughly 1% of the Sun's mass), carbon (0.3%), neon
Photosphere
18082753
as much mass then the Sun does. As a result, stars like Kapteyn's Star have the ability to live up to 100–200 billion years, 10–20 times longer than the Sun will live. Another crucial factor in habitability is temperature and atmospheric properties. The estimated equilibrium temperature for Kapteyn b is around , too cold to support liquid water on the surface. Without the proper greenhouse gases in its atmosphere (if it has one), it is likely to be a planet covered in ice. However, if it has enough in its atmosphere, the surface temperature may rise enough to have water
Kapteyn b
3803061
between the temperature of the black sectors, exposed to the sun, and the temperature of the white sectors, sectors not exposed to the sun or better said in the shades. In all thermopile technology, irradiation is proportional to the difference between the temperature of the sun exposed area and the temperature of the shadow area. In order to attain the proper directional and spectral characteristics, a thermopile pyranometer is constructed with the following main components: In the modern thermopile pyranometers the active (hot) junctions of the thermopile are located beneath the black coating surface and are heated by the radiation
Pyranometer
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which it absorbs it: Substituting the expressions for solar and planet power in equations 1–6 and simplifying yields the estimated temperature of the planet, ignoring greenhouse effect, "T": In other words, given the assumptions made, the temperature of a planet depends only on the surface temperature of the Sun, the radius of the Sun, the distance between the planet and the Sun, the albedo and the IR emissivity of the planet. Notice that a gray (flat spectrum) ball where formula_48 comes to the same temperature as a black body no matter how dark or light gray . Substituting the measured
Black-body radiation
680591
liquid droplets), smaller particles need a higher ambient relative humidity to maintain equilibrium than larger particles do. The following formula gives relative humidity at equilibrium: where formula_45 is the saturation vapor pressure above a particle at equilibrium (around a curved liquid droplet), "p" is the saturation vapor pressure (flat surface of the same liquid) and "S" is the saturation ratio. Kelvin equation for saturation vapor pressure above a curved surface is: where "r" droplet radius, "σ" surface tension of droplet, "ρ" density of liquid, "M" molar mass, "T" temperature, and "R" molar gas constant. There are no general solutions to
Aerosol
12551639
unit increment, the 13th CGPM also held in Resolution 4 that "The kelvin, unit of thermodynamic temperature, is equal to the fraction of the thermodynamic temperature of the triple point of water." In 2005, the Comité International des Poids et Mesures (CIPM), a committee of the CGPM, affirmed that for the purposes of delineating the temperature of the triple point of water, the definition of the Kelvin thermodynamic temperature scale would refer to water having an isotopic composition specified as Vienna Standard Mean Ocean Water. In 2018, Resolution A of the 26th CGPM adopted a significant redefinition of SI base
Kelvin
12785302
the International System of Units, it has subsequently been redefined in terms of the equivalent fixing points on the Kelvin scale, and so that a temperature increment of one degree Celsius is the same as an increment of one kelvin, though they differ by an additive offset of 273.15. The United States commonly uses the Fahrenheit scale, on which water freezes at and boils at at sea-level atmospheric pressure. Many scientific measurements use the Kelvin temperature scale (unit symbol: K), named in honor of the Scots-Irish physicist who first defined it. It is a thermodynamic or absolute temperature scale. Its
Temperature
10271086
can be seen in the adjacent picture contributes to the moon's anti-greenhouse effect and lowers the temperature by reflecting sunlight away from the satellite. The thick atmosphere blocks most visible wavelength light from the Sun and other sources from reaching Titan's surface. Triton, Neptune's largest moon, has a tenuous nitrogen atmosphere with small amounts of methane. Tritonian atmospheric pressure is about 1Pa. The surface temperature is at least 35.6 K, with the nitrogen atmosphere in equilibrium with nitrogen ice on Triton's surface. Triton has increased in absolute temperature by 5% since 1989 to 1998. A similar rise of temperature on
Extraterrestrial atmosphere
12785345
scientists measure temperature using the Celsius scale and thermodynamic temperature using the Kelvin scale, which is the Celsius scale offset so that its null point is = , or absolute zero. Many engineering fields in the U.S., notably high-tech and US federal specifications (civil and military), also use the Kelvin and Celsius scales. Other engineering fields in the U.S. also rely upon the Rankine scale (a shifted Fahrenheit scale) when working in thermodynamic-related disciplines such as combustion. The basic unit of temperature in the International System of Units (SI) is the kelvin. It has the symbol K. For everyday applications,
Temperature
4755801
temperature structure of the three oceans display dramatic asymmetries. The equatorial Pacific and Atlantic both have cool surface temperatures in Northern Summer in the east, while cooler surface temperatures prevail only in the western Indian Ocean. These changes in surface temperature reflect changes in the depth of the thermocline. Changes in the Walker Circulation with time occur in conjunction with changes in surface temperature. Some of these changes are forced externally, such as the seasonal shift of the Sun into the Northern Hemisphere in summer. Other changes appear to be the result of coupled ocean-atmosphere feedback in which, for example,
Walker circulation
8417695
Kelvin equation The Kelvin equation describes the change in vapour pressure due to a curved liquid–vapor interface, such as the surface of a droplet. The vapor pressure at a convex curved surface is higher than that at a flat surface. The Kelvin equation is dependent upon thermodynamic principles and does not allude to special properties of materials. It is also used for determination of pore size distribution of a porous medium using adsorption porosimetry. The equation is named in honor of William Thomson, also known as Lord Kelvin. The Kelvin equation may be written in the form where formula_2 is
Kelvin equation
462046
was widely believed that the discovery of radioactivity had invalidated Thomson's estimate of the age of the Earth. Thomson himself never publicly acknowledged this because he thought he had a much stronger argument restricting the age of the Sun to no more than 20 million years. Without sunlight, there could be no explanation for the sediment record on the Earth's surface. At the time, the only known source for the solar power output was gravitational collapse. It was only when thermonuclear fusion was recognised in the 1930s that Thomson's age paradox was truly resolved. In the winter of 1860–1861 Kelvin
William Thomson, 1st Baron Kelvin
160595
higher equilibrium temperature than if the atmosphere were absent. An ideal thermally conductive blackbody at the same distance from the Sun as Earth would have a temperature of about . However, because Earth reflects about 30% of the incoming sunlight, this idealized planet's effective temperature (the temperature of a blackbody that would emit the same amount of radiation) would be about . The surface temperature of this hypothetical planet is below Earth's actual surface temperature of approximately . The basic mechanism can be qualified in a number of ways, none of which affect the fundamental process. The atmosphere near the
Greenhouse effect
2115007
in the first basin and easterly winds in the second and third basins. As a result, the temperature structure of the three oceans display dramatic asymmetries. The equatorial Pacific and Atlantic both have cool surface temperatures in northern summer in the east, while cooler surface temperatures prevail only in the western Indian Ocean. These changes in surface temperature reflect changes in the depth of the thermocline. Changes in the Walker circulation with time occur in conjunction with changes in surface temperature. Some of these changes are forced externally, such as the seasonal shift of the sun into the Northern Hemisphere
El Niño–Southern Oscillation
4186434
Sun the existence of a temperature minimum region means that limb brightening should start to dominate at far-infrared or radio wavelengths. Outside the lower atmosphere, and well above the temperature-minimum region, we find the million-kelvin solar corona. For most wavelengths this region is optically thin, i.e. has small optical depth, and must therefore be limb-brightened if spherically symmetric. Further complication comes from the existence of rough (three-dimensional) structure. The classical analysis of stellar limb darkening, as described below, assumes the existence of a smooth hydrostatic equilibrium, and at some level of precision this assumption must fail (most obviously in sunspots
Limb darkening
15706991
voltage, Ea is the activation energy of HCI, typically −0.2 to −0.1eV, "k" is Boltzmann’s constant, and "T" is temperature in kelvins. NBTI: λ = A εoxm VTμp exp( -Ea / kT) where A is determined empirically by normalizing the above equation, m = 2.9, VT is the thermal voltage, μP is the surface mobility constant, Ea is the activation energy of NBTI, k i s Boltzmann's constant, and T is the temperature in Kelvin The resources and successes with integrated circuits, and a review of some of the drivers of field failures, subsequently motivated the reliability physics community to
Physics of failure
2284615
Negative temperature In quantum thermodynamics, certain systems can achieve negative temperature; that is, their temperature can be expressed as a negative quantity on the Kelvin or Rankine scales. A system with a truly negative temperature on the Kelvin scale is "hotter" than any system with a positive temperature. If a negative-temperature system and a positive-temperature system come in contact, heat will flow from the negative- to the positive-temperature system. A standard example of such a system is population inversion in laser physics. Temperature is loosely interpreted as the average kinetic energy of the system's particles. The existence of negative temperature,
Negative temperature
3607629
heliophysics. It was unclear as to why the temperature of the sun's corona is hot (about one million degrees Kelvin) compared to its surface (i.e. the photosphere), which is only a few thousand degrees. Intuitively, it would make sense to see a decrease in temperature when moving away from a heat source, but this does not seem to be the case even though the photosphere is denser and would generate more heat than the corona. In 1942, Hannes Alfvén proposed in "Nature" the existence of an electromagnetic-hydrodynamic wave which would carry energy from the photosphere to heat up the corona
Alfvén wave
2284634
low entropy negative temperature state. In the negative temperature state, the atoms macroscopically occupy the maximum momentum state of the lattice. The negative temperature ensembles equilibrated and showed long lifetimes in an anti-trapping harmonic potential. Negative temperature In quantum thermodynamics, certain systems can achieve negative temperature; that is, their temperature can be expressed as a negative quantity on the Kelvin or Rankine scales. A system with a truly negative temperature on the Kelvin scale is "hotter" than any system with a positive temperature. If a negative-temperature system and a positive-temperature system come in contact, heat will flow from the negative-
Negative temperature
6627605
estimate of the average surface temperature, the local temperature varies greatly, as is typical for bodies without atmospheres. A rough estimate of the maximum temperature can be obtained by assuming that when the Sun is overhead, the surface is in thermal equilibrium with the instantaneous solar radiation. This gives "average" "sub-solar" temperature of where formula_18 is the average temperature calculated as above. At "perihelion", the radiation is maximised, and where formula_26 is the eccentricity of the orbit. Infra-red observations are commonly combined with albedo to measure the temperature more directly. For example, L.F.Lim et al. [Icarus, Vo. 173, 385 (2005)]
Standard asteroid physical characteristics
16123110
Natalie Batalha, one of the scientists on the Kepler Space Telescope project, has speculated, "If it is mostly ocean with a small rocky core, it's not beyond the realm of possibility that life could exist in such an ocean". This possibility has spurred SETI to perform research on top candidates for extraterrestrial life. The host star, Kepler-22, is a G-type star that is 3% less massive than the Sun and 2% smaller in volume. It has a surface temperature of compared with the Sun, which has a surface temperature of . The star is about 4 billion years old. In
Kepler-22b
12383565
the two planets' surface temperatures are roughly equal. The upper regions of Neptune's troposphere reach a low temperature of . At a depth where the atmospheric pressure equals , the temperature is . Deeper inside the layers of gas, the temperature rises steadily. As with Uranus, the source of this heating is unknown, but the discrepancy is larger: Uranus only radiates 1.1 times as much energy as it receives from the Sun; whereas Neptune radiates about 2.61 times as much energy as it receives from the Sun. Neptune is the farthest planet from the Sun, yet its internal energy is
Neptune
12785375
higher energy than at positive temperature, and may be said to be in fact hotter at negative temperatures. When brought into contact with a system at a positive temperature, energy will be transferred from the negative temperature regime to the positive temperature region. Temperature Temperature is a physical quantity expressing hot and cold. It is measured with a thermometer calibrated in one or more temperature scales. The most commonly used scales are the Celsius scale (formerly called "centigrade") (denoted °C), Fahrenheit scale (denoted °F), and Kelvin scale (denoted K). The kelvin (spelled with a lower-case k) is the unit of
Temperature
7946218
the sorption process (exothermic), is the change in entropy, is the ideal gas constant, T is the temperature in Kelvin, is the molar volume of the metal, is the radius of the nanoparticle and is the surface free energy of the particle. From the above relation we see that the enthalpy and entropy change of desorption processes depend on the radius of the nanoparticle. Moreover, a new term is included that takes into account the specific surface area of the particle and it can be mathematically proven that a decrease in particle radius leads to a decrease in the release
Hydrogen storage
18134276
effective surface temperature of around 5338 K (the Sun has an approximate surface temperature of 5778 K), a mass around 1.13 times, and diameter 1.23 times that of the Sun. It has a debris disk calculated to span from a radius of 35 to 165 astronomical units (AU), as well as a substellar companion with 36 times the mass of Jupiter orbiting at a distance of 16 AU, discovered in 2008. The companion, currently known as PZ Tel B, is thought to be a brown dwarf; however it is possible (though very unlikely) that it is an extremely large Jupiter-like
PZ Telescopii
10448372
has a mass of 2.7 and a radius of around 12.6 . It has a surface temperature of 4901 K and is 625 million years old. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K. The star's apparent magnitude, or how bright it appears from Earth's perspective, is 3.53. Therefore, Epsilon Tauri can be seen with the naked eye. Epsilon Tauri b orbits its star with nearly 97 times the Sun's luminosity (97 ) every 645 days at a distance of 1.93 AU (compared to Mars' orbital distance from the Sun,
Epsilon Tauri b
19659182
radius (4600 km) for an albedo of 0.5. It has a surface temperature of , far hotter than the surface of Venus. The planet orbits a (K-type) star named Kepler-1520. The star has a mass of 0.76 and a radius of 0.71 . It has a temperature of 4677 K and is 4.47 billion years old. In comparison, the Sun is 4.6 billion years old and has a surface temperature of 5778 K. The star's apparent magnitude, or how bright it appears from Earth's perspective, is 16.7. Therefore, it is too dim to be seen with the naked eye. Kepler-1520b
Kepler-1520b
10395313
main sequence, Iota Draconis was probably a Class A star with surface temperature between 7,400-10,000K. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K. The star's apparent magnitude, a measure of how bright it appears from Earth, is 3.31. Therefore, Iota Draconis can be seen with the naked eye. Iota Draconis b orbits its star with nearly 55 times the Sun's luminosity (55 ) every 511 days at an average distance of 1.275 AU (compared to Mars' orbital distance from the Sun, which is 1.52 AU) It has a very eccentric
Iota Draconis b
19675705
many super-Earth sized planets, Proxima Centauri b could have an icy composition like Neptune, with a thick layer of hydrogen on its surface; the likelihood that this is the case has been calculated to be greater than 10%. The planet has an equilibrium temperature of . The planet orbits an M-type red dwarf named Proxima Centauri. The star has a mass of and a radius of . It has a surface temperature of 3042 K and is 4.85 billion years old. In comparison, the Sun is 4.6 billion years old and has a surface temperature of 5778 K. Proxima Centauri
Proxima Centauri b
8417703
that acts as nucleation centers. Actually, vapours seem to be much less finicky than solutions about the sort of nuclei required. This is because a liquid will condense on almost any surface, but crystallization requires the presence of crystal faces of the proper kind. Kelvin equation The Kelvin equation describes the change in vapour pressure due to a curved liquid–vapor interface, such as the surface of a droplet. The vapor pressure at a convex curved surface is higher than that at a flat surface. The Kelvin equation is dependent upon thermodynamic principles and does not allude to special properties of
Kelvin equation
14094080
Kelvin–Stokes theorem The Kelvin–Stokes theorem (named for Lord Kelvin and George Stokes), also known as the curl theorem, is a theorem in vector calculus on . Given a vector field, the theorem relates the integral of the curl of the vector field over some surface, to the line integral of the vector field around the boundary of the surface. The Kelvin–Stokes theorem is a special case of the “generalized Stokes' theorem.” In particular, a vector field on can be considered as a 1-form in which case curl is the exterior derivative. If is defined in a region with smooth surface
Kelvin–Stokes theorem
12785313
triple point of water, a point which can be reliably reproduced as a standard experimental phenomenon, at a numerical value of 273.16 kelvins. The Kelvin scale is also called the thermodynamic scale. However, to demonstrate that its numerical value is indeed arbitrary, it is useful to point out that an alternate, less widely used absolute temperature scale exists called the Rankine scale, made to be aligned with the Fahrenheit scale as Kelvin is with Celsius. The thermodynamic definition of temperature is due to Kelvin. It is framed in terms of an idealized device called a Carnot engine, imagined to define
Temperature
19468
Sun, with a surface temperature of 4677 K. Gamma Apodis is a yellow giant of spectral type G8III located 150 ± 4 light-years away, with a magnitude of 3.87. It is approximately 63 times as luminous the Sun, with a surface temperature of 5279 K. Delta Apodis is a double star, the two components of which are 103 arcseconds apart and visible through binoculars. Delta is a red giant star of spectral type M4III located 630 ± 30 light years away. It is a semiregular variable that varies from magnitude +4.66 to +4.87, with pulsations of multiple periods of 68.0,
Apus
5711574
oscillating Ap star, with a period of 16.2 minutes. Of spectral type A5V with a surface temperature of around 7980 K, it has around 2.09 times the mass of the Sun, 2.63 times its radius and 25.3 times its luminosity. The smaller star is a main sequence star with spectral type F2, a surface temperature of around 6750 K, around 1.4 times the mass of the Sun, 1.56 times its radius, and between 4 and 5 times its luminosity. The system is around 530 million years old. Beta Coronae Borealis Beta Coronae Borealis (β Coronae Borealis, abbreviated Beta CrB, β
Beta Coronae Borealis
12551649
constant and can be used to determine the noise temperature of a circuit using the Friis formulas for noise. The symbol is encoded in Unicode at code point . However, this is a compatibility character provided for compatibility with legacy encodings. The Unicode standard recommends using instead; that is, a normal capital K. "Three letterlike symbols have been given canonical equivalence to regular letters: , , and . In all three instances, the regular letter should be used." Kelvin The Kelvin scale is an absolute thermodynamic temperature scale using as its null point absolute zero, the temperature at which all
Kelvin
17918525
spectral type B2V with around 10 times the Sun's mass and 6 times its radius. With a surface temperature of 20,000 K, it is around 5,000 times as luminous as the Sun. QZ Carinae B1 is a hot blue giant that is expanding and cooling away from the main sequence. It is of spectral type O8III with around 14.1 times the Sun's mass and 26.9 times its radius. With a surface temperature of 32,573 K, it is around 200,000 times as luminous as the Sun. Partner B2 is a hot main sequence star of spectral type O9V with around 28
QZ Carinae
449546
which has a minimum surface temperature of and maximum surface temperature of , even though Venus is nearly twice Mercury's distance from the Sun and thus receives only 25% of Mercury's solar irradiance. This temperature is higher than that used for sterilization. Studies have suggested that billions of years ago Venus's atmosphere was much more like Earth's than it is now, and that there may have been substantial quantities of liquid water on the surface, but after a period of 600 million to several billion years, a runaway greenhouse effect was caused by the evaporation of that original water, which
Venus
4531330
but passes it through a surface so large that the star radiates little per unit of surface area. A star near the middle of the spectrum, such as the modest Sun or the giant Capella radiates more energy per unit of surface area than the feeble red dwarf stars or the bloated supergiants, but much less than such a white or blue star as Vega or Rigel. The effective (blackbody) temperature of a planet can be calculated by equating the power received by the planet with the power emitted by a blackbody of temperature . Take the case of a
Effective temperature
12551638
of 0.00366—the accepted expansion coefficient of gas per degree Celsius relative to the ice point, giving a remarkable consistency to the currently accepted value. In 1954, Resolution 3 of the 10th General Conference on Weights and Measures (CGPM) gave the Kelvin scale its modern definition by designating the triple point of water as its second defining point and assigned its temperature to exactly 273.16 kelvins. In 1967/1968, Resolution 3 of the 13th CGPM renamed the unit increment of thermodynamic temperature "kelvin", symbol K, replacing "degree Kelvin", symbol °K. Furthermore, feeling it useful to more explicitly define the magnitude of the
Kelvin
13217232
March 1960 lunar eclipse A total lunar eclipse took place on March 13, 1960. The moon passed through the center of the Earth's shadow. This is the 53rd member of Lunar Saros 122. The next event is the March 1978 lunar eclipse. This eclipse afforded astrophysicist Richard W. Shorthill the opportunity to make the first infrared pyrometric temperature scans of the lunar surface, and led to his discovery of the first lunar "hot spot" observed from Earth. Shorthill found that the temperature of the floor of the Tycho crater was 216° Kelvin (—57° C), significantly higher than the 160°K (—113°
March 1960 lunar eclipse
17641133
"h", and "i" derives from the order of discovery. The designation of "b" is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet. In the case of Kepler-90, there are eight planets discovered, so designations up to "i" are used. Kepler-90 is a G-type star that is approximately 120% the mass and radius of the Sun. It has a surface temperature of 6080 K, and an estimated age of around 2 billion years. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K.
Kepler-90
13585107
BD+14 4559 BD+14 4559 is a 10th magnitude K-type main sequence star located approximately 158 light years away in the constellation of Pegasus. On June 10, 2009, an exoplanet (BD+14 4559 b) was found in orbit by Niedzielski et al. using the Hobby-Eberly Telescope. BD+14 4559 is a K-type star that is approximately 86% the mass of and 95% the radius of the Sun. It has a surface temperature of 5008 K and is likely about 3 billion years old based on its characteristics. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of
BD+14 4559
446117
between 0.8 and 1.6 Astronomical Units (AU). The brighter component is a hot blue main-sequence star of spectral type O7.5 and is around 280,000 times as luminous, is around 30 times as massive and is 17 times the diameter of our Sun with a surface temperature of 35,000 K. The second component is an extremely rare example of hot star known as a Wolf–Rayet star, and is the brightest example in the sky. It has a surface temperature of 57,000 and is around 170,000 times as luminous as our sun, though it radiates most of its energy in the ultraviolet
Vela (constellation)
17895858
paper, who use Kepler-138b. This has led to the unusual situation of having one star with two "b" planets in orbit and two different base-names for the orbiting planets. Kepler-138 is a red dwarf with approximately 57% the mass of and 54% the radius of the Sun. It has a surface temperature of 3871 ± 58 K. In comparison, the Sun has a surface temperature of 5778 K. Kepler-138's apparent magnitude (bright it appears from Earth's perspective) is 12.925, too dim to be seen with the naked eye. All known planets transit the star; this means that all three planets'
Kepler-138
19310295
the moons in the outer Solar System. This might be a result of the relatively high temperature of Ceres's surface, the maximum temperature with the Sun overhead was estimated from measurements to be on 5 May 1991. In a vacuum, ice is unstable at this temperature. Material left behind by the sublimation of surface ice could explain the dark surface of Ceres compared to the icy moons of the outer Solar System. Ceres's oblateness is consistent with a differentiated body, a rocky core overlain with an icy mantle. This 100-kilometer-thick mantle (23%–28% of Ceres by mass; 50% by volume) contains
Geology of Ceres
15294966
"e", "f", and "g", distinguishers that are tagged onto the name of their home star. Kepler-11 is a G-type star that is approximately 104% the mass of and 102% the radius of the Sun. It has a surface temperature of about 5836 K and is estimated to have an age of around 3.2 billion years. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K. With an apparent magnitude of 14.2, it is too faint to be seen with the naked eye. All known planets transit the star; this means that all
Kepler-11
17115740
Moon. Due to its small size, it is very likely Kepler-37b is a rocky planet with a solid surface. Furthermore, it is too hot to support liquid water on its surface. The planet orbits a (G-type) star similar to the Sun, named Kepler-37, orbited by a total of four planets. The star has a mass of 0.80 and a radius of 0.79 . It has a temperature of 5417 K and is 5.66 billion years old. In comparison, the Sun is 4.6 billion years old and has a temperature of 5778 K. The star's apparent magnitude, or how bright it
Kepler-37b
4588926
surface temperature will decrease and the total energy output (luminosity) of the star will increase as the surface area increases. At a certain point, the helium at the core of the star will reach a pressure and temperature where it can begin to undergo nuclear fusion through the triple-alpha process. For a star with less than 1.8 times the mass of the Sun, this will occur in a process called the helium flash. The evolutionary track of the star will then carry it toward the left of the HR diagram as the surface temperature increases under the new equilibrium. The
Tip of the red-giant branch
5609719
"U" is the heat transfer coefficient (in watts per kelvin per square meter) and "Ar" is the exchange area. Note that estimating the heat transfer coefficient may be quite complicated. This holds both for cocurrent flow, where the streams enter from the same end, and for counter-current flow, where they enter from different ends. In a cross-flow, in which one system, usually the heat sink, has the same nominal temperature at all points on the heat transfer surface, a similar relation between exchanged heat and LMTD holds, but with a correction factor. A correction factor is also required for other
Logarithmic mean temperature difference
1532062
Fermi energy of the order: where "m" is the electron mass. This Fermi energy corresponds to a Fermi temperature of the order of 10 kelvins, much higher than the temperature of the sun surface. Any metal will boil before reaching this temperature under atmospheric pressure. Thus for any practical purpose a metal, can be considered as a Fermi gas at zero temperature as a first approximation (normal temperatures are small compared to "T"). Stars known as white dwarfs have mass comparable to our Sun, but have about a hundredth of its radius. The high densities mean that the electrons are
Fermi gas
19266261
a temperature of , somewhat cooler than the equilibrium temperature of the Earth. It has a mass of 7.2 , and a likely radius of around 1.05 , based on its high mass. The planet orbits an (F-type) star named Kepler-419. The star has a mass of 1.39 and a radius of 1.75 . It has a surface temperature of 6430 K and is 2.8 billion years old. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K. The star's apparent magnitude, or how bright it appears from Earth's perspective, is 12.
Kepler-419c
462270
farther from the Sun (about 5%, or about 8 million kilometers), the conditions which allow the three forms to be present simultaneously would be far less likely to exist. Earth's gravity allows it to hold an atmosphere. Water vapor and carbon dioxide in the atmosphere provide a temperature buffer (greenhouse effect) which helps maintain a relatively steady surface temperature. If Earth were smaller, a thinner atmosphere would allow temperature extremes, thus preventing the accumulation of water except in polar ice caps (as on Mars). The surface temperature of Earth has been relatively constant through geologic time despite varying levels of
Water
16186469
b, which, coincidentally, orbits a stellar remnant, much like the planets of Kepler-70. The host star, Kepler-70 (also formally known as "KOI-55", "2MASS J19452546+4105339" or "KIC 5807616"), is a subdwarf B-type star that has left its red giant stage of its lifetime – according to the Extrasolar Planets Encyclopedia – about ago. It has a surface temperature of 27730 ± 270 K, nearly 6 times as hot as the surface temperature of the Sun, which has a surface temperature of 5778 K. The star has a mass of 0.496 and a radius of 0.203 It is expected to become a
Kepler-70b
14919162
the most precise distance estimate of 2MASS 0937+2931 is trigonometric parallax, published in 2009 by Schilbach et al.: 163.39 ± 1.76 mas, corresponding to a distance 6.12 ± 0.07 pc, or 19.96 ± 0.22 ly. A less precise parallax of this object, measured under U.S. Naval Observatory Infrared Astrometry Program, was published in 2004 by Vrba et al. 2MASS 0937+2931 has an unusual spectrum, indicating a metal-poor atmosphere and/or a high surface gravity (high pressure at the surface). Its effective temperature is estimated at about 800 Kelvin. The Research Consortium On Nearby Stars (RECONS) estimates the brown dwarf to be
2MASSI J0937347+293142
4617153
luminous than the Sun and has a surface temperature of , double that of the Sun. This high temperature produces light with a simple spectrum, making it ideal for examining the interstellar gas and dust between Earth and the star. Like many stars of its kind, it is spinning rapidly, over 100 times faster than the Sun with a projected rotational velocity of . The measured angular diameter of the primary star is 0.801 mas. At the estimated distance of this system, this yields a physical size of about 4.9 times the radius of the Sun. This type of massive,
Beta Librae
8412233
to be in equilibrium or have a temperature, two-thirds of the average energy is often referred to as the temperature, since for a Maxwell–Boltzmann distribution with three degrees of freedom, formula_1. The SI unit of temperature is the kelvin (K), but using the above relation the electron temperature is often expressed in terms of the energy unit electronvolt (eV). Each kelvin (1 K) corresponds to 8.6173324(78)×10 eV; this factor is the ratio of the Boltzmann constant to the elementary charge. Each eV is equivalent to 11,605 kelvins. It can be calculated by the relation formula_2. The electron temperature of a
Electron temperature
2618984
to monitor and control their environment, such as heat and pH levels; however, if these elements are not regulated, the cells may die or it may result in unwanted reactions. PDMS has been found to absorb acoustic energy, causing the PDMS to heat up quickly (exceeding 2000 Kelvin/second). The use of SAW as a way to heat these PDMS devices, along with liquids inside microchannels, is now a technique that can be done in a controlled manner with the ability to manipulate the temperature to within 0.1 °C. Surface acoustic waves can be used for flow measurement. SAW relies on
Surface acoustic wave
12551648
an effective temperature of . Digital cameras and photographic software often use colour temperature in K in edit and setup menus. The simple guide is that the higher the colour temperature, the more white or blue the image will be. The reduction in colour temperature will give an image more dominated by reddish, "warmer" colours. In electronics, the kelvin is used as an indicator of how noisy a circuit is in relation to an ultimate noise floor, i.e. the noise temperature. The so-called Johnson–Nyquist noise of discrete resistors and capacitors is a type of thermal noise derived from the Boltzmann
Kelvin
361642
the same composition as the solar atmosphere. In 1983, it was claimed that it was fractionation in the Sun itself that caused the isotopic-composition relationship between the planetary and solar-wind-implanted noble gases. The structure of the Sun contains the following layers: The core of the Sun extends from the center to about 20–25% of the solar radius. It has a density of up to (about 150 times the density of water) and a temperature of close to 15.7 million kelvins (K). By contrast, the Sun's surface temperature is approximately 5,800 K. Recent analysis of SOHO mission data favors a faster
Sun
422820
surface pressure of the star, which in turn is determined by the temperature and surface gravity. This technique was used to determine the surface gravity of Tau Ceti. The , or logarithm of the star's surface gravity, is about 4.4, very close to the for the Sun. The luminosity of Tau Ceti is equal to only 55% of the Sun's luminosity. A terrestrial planet would need to orbit this star at a distance of about in order to match the solar insolation level of Earth. This is approximately the same as the average distance between Venus and the Sun. The
Tau Ceti
14211417
dissipate 0.25 W each. That means the bridged resistors will have a quarter of the self-heating and a quarter of the temperature rise. For the divider to maintain accuracy, the temperature rise from self-heating must be limited. Getting very low temperature coefficients keeps the effect of temperature variations small. Reducing the thermal resistance of the resistors keeps the temperature rise small. Commercial Kelvin–Varley dividers use wire-wound resistors and immerse them in an oil bath (sometimes the first decade only). The thermoelectric effect causes junctions of different metals to generate voltages if the junctions are at different temperatures (see also "thermocouple").
Kelvin–Varley divider
4835626
measure the very same temperature with ease due to the advantages of a comprehensive international calibration standard featuring many conveniently spaced, reproducible, defining points spanning a wide range of temperatures. Although “International Temperature Scale of 1990” has the word “scale” in its title, this is a misnomer that can be misleading. ITS–90 is not a scale; it is an "equipment calibration standard". Temperatures measured with equipment calibrated per ITS–90 may be expressed using any temperature scale such as Celsius, Kelvin, Fahrenheit, or Rankine. For example, a temperature can be measured using equipment calibrated to the kelvin-based ITS–90 standard, and that
International Temperature Scale of 1990
675507
circa becomes homothermic (same temperature throughout) at around because of water mixing. The sun continues to heat up the surface layer, and at the peak in August can reach up to about in the main sections and in shallow bays in the southern half of the lake. During this time, the pattern is inverted compared to the winter and spring, as the water temperature falls with increasing depth. As the autumn begins, the surface temperature falls again and a second homothermic period at around of the upper circa occurs in October–November. In the deepest parts of the lake, from about
Lake Baikal