New Evidence That All Stars Are Born In Pairs (phys.org)

InfiniteZero shares a report from Phys.Org: 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 sun-like 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. 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 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 (more than 500 astronomical units) binaries," said co-author Steven Stahler, a UC Berkeley research astronomer. "These systems then either shrink or break apart within a million years." The study has been published in April on the arXiv server.

Comments

Frost Fernch Pots

[Hognoxious]

Anyone else read it as Paris? I thought it was going to be some bizarre statistical thing drawn from IMDB.

More coffee needed, I think.

ok so if stars are born in pairs

[Anonymous Coward]

That raises the question, what happened to ours?

Re:ok so if stars are born in pairs

[rgbatduke]

Jupiter. It simply lost mass as the coalesced to the larger of the pair, with some of it becoming the other planets and most falling into what became the sun. It left Jupiter itself too small to ignite.

Or, of course, their mathematical model could be completely wrong, because the statement that the "only" mathematical model that could explain the data is one where all stars have partners sounds like science-bullshit-fu of the first order. At least they could have the decency to add "of the ones we thought of" or "of the ones we tried". As it is, we're left with proving that the Sun's supposed partner DOESN'T exist, and since it is very difficult to prove that something doesn't exist when it could be "invisible" in any of the countless ways someting can be invisible in space -- too far away, too small, too dark, too much of it made of of dark matter, concealed by invisible fairies, fallen through to the evil companion Universe where everybody is left handed and drinks absinthe and cherry soda cocktails.

If it is Jupiter, of course, that makes it easy. It isn't lit, so we know its mass is less than 1/10 (less than 0.075 if you want to be picky) the mass of the sun (no overt fusion, the companion isn't a red dwarf or we couldn't possibly miss it). It has cooled enough to be invisible, which probably adds close to another zero -- if it had a mass 1/80th of the Sun or larger , it would probably have a surface temperature still hot enough to see as it would be a brown dwarf and might sustain some nuclear reactions capable of generating heat in addition to still giving off heat as it slowly collapses. So it pretty much has to be smaller than roughly 13 Jupiter masses, making it technically not a star no matter what. Well, what do we find when we look for very large non-brown-dwarf objects nearby? Jupiter! And heck, through Saturn in for good measure! Jupiter has 1/1000 the mass of the sun, large enough that it is probably still losing heat via its own gravitational collapse but not enough to ignite any serious sustained fusion process. If the proto-star split early enough into Jupiter and Saturn (and the rest of the planets) then the Sun simply won the war for material by having a lot more gravity and hence sweeping up most of the dust before it lit and fusion drove the rest of the material away.

Which leads us to the remaining problem with their model. They're basing their claim on stellar formation in a dense cloud that created an extended star cluster. Perhaps that isn't a completely general starforming environment, and stars that form from smaller clouds tend to win the race for material and blow the starforming dust away on their newborne light before their smaller companions reach "star" size, even brown dwarf size.

That would explain why a LOT of stars seem to have Jupiter-scale planets (not that our exoplanet search isn't naturally biased towards finding these planets BECAUSE of their size). I'll bet there is an "alternative" model for star formation that would embrace this possibility and still explain the data from their star cluster but no, I'm sure that they have considered EVERY possibility in order to conclude that it is impossible for the sun not to have a star-sized companion, when it simply doesn't, at least not anywhere anyone can see when looking pretty carefully and with good instruments that would be very, very likely to show it up if it was there.

All stars born in Paris

[calken1979]

I was scratching my head to think of famous French people only to realise I misread the title.

Simple question

[Anonymous Coward]

Does the presence of a sibling star and its gravity have an impact on planet formation?

Re: Astronomers Research

[Anonymous Coward]

The supposed periodicity of mass extinctions every 26 million years has been disproved. Besides, stars can and do move through the solar system from time to time. Yes, they can and do affect Oort Cloud objects in the process. But it's nothing so periodic as Nemesis supposedly is. It's pretty unlikely that Nemesis exists at all.