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View Full Version : Can The Sun's Siblings Be Found?

SagittariusAStar
2010-Nov-22, 12:47 AM
Maybe not (http://news.sciencemag.org/sciencenow/2010/11/can-the-suns-siblings-be-found.html).

Tom Mazanec
2010-Nov-25, 08:59 AM
There was a Scientific American article on this recently. It had most of the sun's siblings in an arc spanning about a quarter of the galaxy. It suggested GAIA might be able to determine the stars by their very small proper motions relative to the sun, IIRC.
If you had asked me this question a couple years ago, I would have said "No and heck no!" Just the fact that it is somewhat plausible is astounding to me.

SagittariusAStar
2010-Nov-25, 02:50 PM
Yes, the author of that Scientific American article is quoted in the link.

AndrewJ
2010-Nov-25, 08:52 PM
Does anyone know a likely probability for any given star within, say, 100 light years being a sibling of our Sun?

SagittariusAStar
2010-Nov-26, 09:38 PM
Within 100 light-years of the Sun are about 12,000 star systems.

If only 1 or 2 siblings lie within that same distance, then the chance that any particular star system within 100 light-years is a sibling is only 0.008 to 0.017 percent.

In the BEST case scenario--in the unlikely event that all 1,000 siblings lie within 100 light-years of us--then the chance that any particular star system within 100 light-years is a sibling is 8 percent.

nota
2010-Nov-27, 01:46 AM
do them assume the exact same metalized content to the shared birth place/time stars

or is there a curve of distance from the supernova that give a different content form the same event ?

AndrewJ
2010-Nov-27, 08:13 PM
In the BEST case scenario--in the unlikely event that all 1,000 siblings lie within 100 light-years of us--then the chance that any particular star system within 100 light-years is a sibling is 8 percent.

No higher than 8% - thanks, an interesting statistic.

neilzero
2013-Jun-21, 06:57 PM
do them assume the exact same metalized content to the shared birth place/time stars

or is there a curve of distance from the supernova that give a different content form the same event ?
Bump. The metalized content of the 8 planets in our solar system varies over a rather large range, so I would expect star siblings to have a rather wide range of metal percentages. Worse the spectrum of light from nearby stars tell us approximately the percentage of metals in the photosphere of the star which may be quite different than the percentages in the interior and the "farther from the center" high vacuum atmosphere. Neil

antoniseb
2013-Jun-21, 07:04 PM
I'm not sure why you bumped this, but presuming this summer's launch of the ESA's Gaia goes off smoothly, we should be able to identify the most closely comoving stars within a few thousand light-years in a systematic way. It is still possible that the Sun was somehow cast out in an interaction that gave it extra momentum away from its siblings, but if not, we should know in a few years which stars are good candidates to be siblings.

BigDon
2013-Jun-21, 08:38 PM
Is there any reason on Earth to think a solar sibling would have a similar mass as the Sun? I can't think of one.

As most of you well know stars of different masses age at vastly different rates.

Where along the main sequence would a two solar mass solar sibling be? Or even a 1.2 solar mass star after thirteen odd billion years? What is that in star years, some fifty-two revolutions around the galaxy? All in slightly different directions, plus interacting gravitationally with anything with mass.

Obviously if the project has gotten this far somebody must have seconded their math, but still...

antoniseb
2013-Jun-21, 09:02 PM
... Where along the main sequence would a two solar mass solar sibling be? Or even a 1.2 solar mass star after thirteen odd billion years? What is that in star years, some fifty-two revolutions around the galaxy? All in slightly different directions, plus interacting gravitationally with anything with mass....
We agree on the more massive stars, a 2.0 solar mass star that formed 4.6 billion years ago should be a white dwarf now. On the other hand the vast majority of the Sun's siblings should be L, M, & K stars. They should be on the main sequence. ... and there's been perhaps 15-20 revolutions since the Sun was formed, but your question is still valid about drift... comparable to how far a main belt asteroid might have drifted from a peer in 15 orbits.

StupendousMan
2013-Jun-21, 10:07 PM
During the 12-15 revolutions of the Milky Way, the Sun's
siblings will have drifted so far away and acquired such different
velocities that there is very little chance that we could
re ognize them.

BigDon
2013-Jun-21, 11:09 PM
I confused the age of the Solar system with the age of the Universe, didn't I?

Well, that sort of deflates my point...not to mention embarrassing.

George
2013-Jun-22, 09:21 PM
The only hope would seem to be the metal and isotope ratios. How likely will the stars in a stellar nursery of about the same mass to have the same ratios, especially given that supernova(e) were around during formation, as is the case for the Sun? Wouldn't the stellar metal ratios vary with distance from these supernovae during the nursery days, or later?