WARCZone is a collection of outsider-uploaded WARCs, which are contributed to the Internet Archive but may or may not be ingested into the Wayback Machine. They are being kept in this location for reference and clarity for the Wayback Team, while also being accessible to the general public who are seeking any particular items they can regarding certain websites. ||||| A radio image of a triple-star system forming within a dusty disk in the Perseus molecular cloud obtained by the Atacama Large Millimeter/submillimeter Array in Chile. 
 
 Nemesis is apparently real, even if its bad reputation is undeserved. 
 
 For decades, some scientists have speculated that the sun has a companion whose gravitational tug periodically jostles comets out of their normal orbits, sending them careening toward Earth. The resulting impacts have caused mass extinctions, the thinking goes, which explains the putative star's nickname: Nemesis. 
 
 Now, a new study reports that almost all sun-like stars are likely born with companions, bolstering the case for the existence of Nemesis. [Solar Quiz: How Well Do You Know the Sun?] 
 
 "We are saying, yes, there probably was a Nemesis, a long time ago," study co-author Steven Stahler, a research astronomer at the University of California, Berkeley, said in a statement. 
 
 But the new results don't paint Nemesis as a murderer: The sibling star probably broke free of the sun and melted into the Milky Way galaxy's stellar population billions of years ago, study team members said. 
 
 Radio image of a very young binary star system, less than about 1 million years old, that formed within a dense core (oval outline) in the Perseus molecular cloud. Credit: SCUBA-2 survey image by Sarah Sadavoy, CfA. 
 
 Multistar systems such as Alpha Centauri — the sun's nearest neighbor, which harbors three stars — are common throughout the Milky Way. Indeed, recent computer-simulation research suggests that most if not all stars are born with companions. 
 
 The new study put this supposition to the observational test. Stahler and lead author Sarah Sadavoy, of the Smithsonian Astrophysical Observatory, studied the Perseus molecular cloud, a large star-forming region about 600 light-years from Earth. 
 
 Radio observations of the Perseus cloud by the Very Large Array in New Mexico and the James Clerk Maxwell Telescope in Hawaii revealed 55 young stars in 24 multistar systems (most of which were binary), as well as 45 single-star systems.. 
 
 "The key here is that no one looked before in a systematic way at the relation of real young stars to the clouds that spawn them," Stahler said. 
 
 Sadavoy and Stahler found that all of the observed "wide binary" systems — the ones with stars separated by at least 500 astronomical units (AU) — were very young. Older binary systems were more compact, the researchers said. (One AU is the average Earth-sun distance: about 93 million miles, or 150 million kilometers). 
 
 This infrared image from the Hubble Space Telescope contains a bright, fan-shaped object (lower right quadrant) thought to be a binary star that emits light pulses as the two stars interact. The primitive binary system is located in the Perseus molecular cloud. Credit: J. Muzerolle (STScI)/NASA/ESA 
 
 The two researchers then did some modeling work to better understand what they were seeing. 
 
 "We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud," Stahler said. "And the only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years." 
 
 In fact, the majority of newborn binary stars — about 60 percent — end up going their separate ways, the duo determined. This was probably the fate of Nemesis and the sun, the new study suggests. 
 
 The paper has been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society. You can read it on the online preprint site arXiv.org. 
 
 Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com. ||||| A new model on how stars are formed has added weight to the hypothesis that most – if not all – stars are born in a litter with at least one sibling. 
 
 Our own star at the centre of the Solar System is probably no exception, and some astronomers suspect that the Sun's estranged twin might be the evil one, blaming it for the death of the dinosaurs. 
 
 After analysing data from a radio survey conducted on a dust cloud in the Perseus constellation, two researchers from UC Berkeley and the Harvard-Smithsonian Astrophysical Observatory have concluded all Sun-like stars are probably born with a companion. 
 
 "We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud, and the only model that could reproduce the data was one in which all stars form initially as wide binaries," said UC Berkeley astronomer Steven Stahler. 
 
 For years, astronomers have wondered if the large number of binary and triple systems of stars in our galaxy are created close to one another, or if they fall in together after they've formed. 
 
 The 'born together' hypothesis has been the favourite, and simulations developed in recent decades have shown almost all stars could be born as multiples that often spin away on their own. 
 
 Empirical evidence supporting these simulations has been limited, unfortunately, which makes this new work rather exciting. 
 
 "Our work is a step forward in understanding both how binaries form and also the role that binaries play in early stellar evolution," said Stahler. 
 
 As part of the VLA nascent disk and multiplicity survey (VANDAM for short), the researchers mapped the radio waves leaking out of a dense cocoon of dust about 600 light-years away that contained a whole nursery of young stars. 
 
 The VANDAM survey allowed for a census of stars younger than half a million years old called Class 0 stars – mere babies in star terms – and stars a little older between 500,000 years and 1 million years, called Class 1. 
 
 Combined with data on the shapes of the surrounding cloud of dust, the scientists found 45 lonely stars, 19 binary star systems, and a further five that contained more than two stars. 
 
 While their results predicted all stars were born as binaries, they amended their conclusion to take into account limitations in their model by saying most stars formed inside the dense cores of dust clouds are born with a partner. 
 
 "I think we have the strongest evidence to date for such an assertion," said Stahler. 
 
 Looking closely at the distances between the stars, the researchers found all binaries separated by a gap of 500 AU or more were Class 0 and lined up with the axis of the egg-shaped cloud surrounding them. 
 
 Class 1 stars, on the other hand, tended to be closer together at around 200 AU and weren't aligned with their 'egg's' axis. 
 
 "We don't yet know quite what it means, but it isn't random and must say something about the way wide binaries form," said Sarah Sadavoy from the Harvard-Smithsonian Astrophysical Observatory. 
 
 If most stars are born with a partner, where's ours? 
 
 A distance of 500 AU is roughly 0.008 light-years, or a bit under 3 light-days. To put it into perspective, Neptune is about 30 AU away, the Voyager 1 probe is currently just under 140 AU away, and the nearest known star Proxima Centauri is 268,770 AU away. 
 
 So if the Sun has a twin, it's almost certainly not easily visible in our neighbourhood. 
 
 But there is an hypothesis that our Sun has a dark twin that likes to swing by every now and then, and stir things up. 
 
 Given the name Nemesis, this theoretical trouble maker has been proposed as a reason behind an apparent 27-million-year cycle of extinctions on Earth, including the one that saw off most of the dinosaurs. 
 
 An astronomer from the University of California Berkeley named Richard Muller proposed 23 years ago that a red dwarf star 1.5 light-years away could periodically travel through the icy outer limits of our Solar System, stirring up material with its gravity, knocking a few more space boulders our way. 
 
 A dim passing star such as a brown dwarf could also explain other anomalies at the fringes of our Solar System, such as the odd, wide orbit of the dwarf planet Sedna. 
 
 There's no sign of Nemesis, but a long lost binary partner for our Sun could fit the bill. 
 
 "We are saying, yes, there probably was a Nemesis, a long time ago," said Stahler. 
 
 In which case, our Sun would have gathered the lion's share of dust and gas it seems, leaving its twin dark and stunted. 
 
 No wonder it's a little pissed off. 
 
 This research is currently on pre-print website, arXiv.org, and has been accepted for publication in an upcoming edition of Monthly Notices of the Royal Astronomical Society. ||||| Did our sun have a twin when it was born 4.5 billion years ago? 
 
 Almost certainly yes — though not an identical twin. And so did every other sunlike star in the universe, according to a new analysis by a theoretical physicist from UC Berkeley and a radio astronomer from the Smithsonian Astrophysical Observatory at Harvard University. 
 
 Many stars have companions, including our nearest neighbor, Alpha Centauri, a triplet system. Astronomers have long sought an explanation. Are binary and triplet star systems born that way? Did one star capture another? Do binary stars sometimes split up and become single stars? 
 
 Astronomers have even searched for a companion to our sun, a star dubbed Nemesis because it was supposed to have kicked an asteroid into Earth’s orbit that collided with our planet and exterminated the dinosaurs. It has never been found. 
 
 The new assertion is based on a radio survey of a giant molecular cloud filled with recently formed stars in the constellation Perseus, and a mathematical model that can explain the Perseus observations only if all sunlike stars are born with a companion. 
 
 “We are saying, yes, there probably was a Nemesis, a long time ago,” said co-author Steven Stahler, a UC Berkeley research astronomer. 
 
 “We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud, and the only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years.” 
 
 In this study, “wide” means that the two stars are separated by more than 500 astronomical units, or AU, where one astronomical unit is the average distance between the sun and Earth (93 million miles). A wide binary companion to our sun would have been 17 times farther from the sun than its most distant planet today, Neptune. 
 
 Based on this model, the sun’s sibling most likely escaped and mixed with all the other stars in our region of the Milky Way galaxy, never to be seen again. 
 
 “The idea that many stars form with a companion has been suggested before, but the question is: how many?” said first author Sarah Sadavoy, a NASA Hubble fellow at the Smithsonian Astrophysical Observatory. “Based on our simple model, we say that nearly all stars form with a companion. The Perseus cloud is generally considered a typical low-mass star-forming region, but our model needs to be checked in other clouds.” 
 
 The idea that all stars are born in a litter has implications beyond star formation, including the very origins of galaxies, Stahler said. 
 
 Stahler and Sadavoy posted their findings in April on the arXiv server. Their paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society. 
 
 Stars birthed in ‘dense cores’ 
 
 
 
 Astronomers have speculated about the origins of binary and multiple star systems for hundreds of years, and in recent years have created computer simulations of collapsing masses of gas to understand how they condense under gravity into stars. They have also simulated the interaction of many young stars recently freed from their gas clouds. Several years ago, one such computer simulation by Pavel Kroupa of the University of Bonn led him to conclude that all stars are born as binaries. 
 
 Yet direct evidence from observations has been scarce. As astronomers look at younger and younger stars, they find a greater proportion of binaries, but why is still a mystery. 
 
 “The key here is that no one looked before in a systematic way at the relation of real young stars to the clouds that spawn them,” Stahler said. “Our work is a step forward in understanding both how binaries form and also the role that binaries play in early stellar evolution. We now believe that most stars, which are quite similar to our own sun, form as binaries. I think we have the strongest evidence to date for such an assertion.” 
 
 According to Stahler, astronomers have known for several decades that stars are born inside egg-shaped cocoons called dense cores, which are sprinkled throughout immense clouds of cold, molecular hydrogen that are the nurseries for young stars. Through an optical telescope, these clouds look like holes in the starry sky, because the dust accompanying the gas blocks light from both the stars forming inside and the stars behind. The clouds can, however, be probed by radio telescopes, since the cold dust grains in them emit at these radio wavelengths, and radio waves are not blocked by the dust. 
 
 The Perseus molecular cloud is one such stellar nursery, about 600 light-years from Earth and about 50 light-years long. Last year, a team of astronomers completed a survey that used the Very Large Array, a collection of radio dishes in New Mexico, to look at star formation inside the cloud. Called VANDAM, it was the first complete survey of all young stars in a molecular cloud, that is, stars less than about 4 million years old, including both single and mulitple stars down to separations of about 15 astronomical units. This captured all multiple stars with a separation of more than about the radius of Uranus’ orbit — 19 AU — in our solar system. 
 
 Stahler heard about the survey after approaching Sadavoy, a member of the VANDAM team, and asking for her help in observing young stars inside dense cores. The VANDAM survey produced a census of all Class 0 stars – those less than about 500,000 years old – and Class I stars – those between about 500,000 and 1 million years old. Both types of stars are so young that they are not yet burning hydrogen to produce energy. 
 
 Sadavoy took the results from VANDAM and combined them with additional observations that reveal the egg-shaped cocoons around the young stars. These additional observations come from the Gould Belt Survey with SCUBA-2 on the James Clerk Maxwell Telescope in Hawaii. By combining these two data sets, Sadavoy was able to produce a robust census of the binary and single-star populations in Perseus, turning up 55 young stars in 24 multiple-star systems, all but five of them binary, and 45 single-star systems. 
 
 Using these data, Sadavoy and Stahler discovered that all of the widely separated binary systems — those with stars separated by more than 500 AU — were very young systems, containing two Class 0 stars. These systems also tended to be aligned with the long axis of the egg-shaped dense core. The slightly older Class I binary stars were closer together, many separated by about 200 AU, and showed no tendency to align along the egg’s axis. 
 
 “This has not been seen before or tested, and is super interesting,” Sadavoy said. “We don’t yet know quite what it means, but it isn’t random and must say something about the way wide binaries form.” 
 
 Egg-shaped cores collapse into two centers 
 
 
 
 Stahler and Sadavoy mathematically modeled various scenarios to explain this distribution of stars, assuming typical formation, breakup and orbital shrinking times. They concluded that the only way to explain the observations is to assume that all stars of masses around that of the sun start off as wide Class 0 binaries in egg-shaped dense cores, after which some 60 percent split up over time. The rest shrink to form tight binaries. 
 
 “As the egg contracts, the densest part of the egg will be toward the middle, and that forms two concentrations of density along the middle axis,” he said. “These centers of higher density at some point collapse in on themselves because of their self-gravity to form Class 0 stars.” 
 
 “Within our picture, single low-mass, sunlike stars are not primordial,” Stahler added. “They are the result of the breakup of binaries. ” 
 
 Their theory implies that each dense core, which typically comprises a few solar masses, converts twice as much material into stars as was previously thought. 
 
 Stahler said that he has been asking radio astronomers to compare dense cores with their embedded young stars for more than 20 years, in order to test theories of binary star formation. The new data and model are a start, he says, but more work needs to be done to understand the physics behind the rule. 
 
 Such studies may come along soon, because the capabilities of a now-upgraded VLA and the ALMA telescope in Chile, plus the SCUBA-2 survey in Hawaii, “are finally giving us the data and statistics we need. This is going to change our understanding of dense cores and the embedded stars within them,” Sadavoy said. 
 
 RELATED INFORMATION
– Did the sun have an "evil twin" that wreaked havoc on Earth, perhaps obliterating the dinosaurs? Scientists think they can answer at least part of that question with near certainty: Yes, the sun had a twin, the Telegraph reports. Whether it was "evil" remains up in the air. New research out of UC Berkeley and Harvard suggests every sun in the universe is born with a fraternal twin. In fact, Earth's closest neighbor, Alpha Centauri, is a triplet system. Astronomers have long puzzled over binary and triplet solar systems and what becomes of sidekick suns, which are actually stars. And in one of space's most tantalizing mysteries, researchers have long theorized that a dwarf star dubbed Nemesis once rattled our solar system so fiercely that it unleashed killer comets toward Earth, obliterating the dinosaurs. "We are saying, yes, there probably was a Nemesis, a long time ago," says study co-author Steven Stahler. The study does not, however, address whether Nemesis had any role in the dinosaurs' fate. Researchers say the wayward sun likely broke free and ambled off into the Milky Way billions of years ago, never to be heard from again, reports Space.com. The website thinks this exonerates Nemesis in regard to dinosaurs: It would have been long gone by the time the dinosaurs arrived. But a post at Science Alert isn't so sure: It notes that one theory holds that Nemesis still swings by our solar system periodically and thus could cause trouble. In the study, scientists used data from giant telescopes in New Mexico and Hawaii, along with a mathematical model they designed, to focus on the star-studded Perseus constellation about 600 light-years away. (This space mystery was finally solved.)