Solar Siblings? The Sun's 'Long-Lost Brother' Revealed

Discussion in 'Astronomy, Exobiology, & Cosmology' started by KilljoyKlown, Nov 20, 2015.

  1. KilljoyKlown Whatever Valued Senior Member

    I've been thinking about this article ever sense I read it, and I am convinced that if we can find all the stars that formed from the same material as our own sun, we might stand a better chance of finding alien life.

    We know our world has all the elements for life and it stands to reason that all other solar systems formed from the same material would also have all the elements for life to form and exist.

    At the time we really can't know for sure that systems formed from clouds of gas and dust other than the one we formed from contain all the needed elements. Maybe they do, but I wouldn't bet on it.
    FOLZONI likes this.
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  3. paddoboy Valued Senior Member

    Most gaseous nebulae are mainly H, He with a sprinkling of the heavier elements from S/N explosions.
    They are also very very large around many tens of L/years in size.
    So I imagine many stellar systems could be a result from the same nebulae.
    The one that stands out in my mind was a famous HST photo that was dubbed, "The Pillars of Creation" Remember it? More commonly known as the Eagle nebula.
    The finger print of many potential stellar formation regions are quite obvious within that photo.
    I actually sat in awe of that photo for many hours and the evidence for how stars and planets come about.

    My own thoughts are that terrestrial planets that have formed in any gaseous nebula, are basically all around the same content, much as all the terrestrial planets in our own solar system.
    As for the potential for life, I see that more dependent on the type of star in the system and its position on the main sequence scale, and the region where any goldilocks zone would be. Magnetic fields and atmospheric density and content also obviously play a part.
    The Alpha Centauri system, a probably trinary group of gravitationally bound stars, [probably, because Proxima Centauri, our closest neigbour, we are not 100% sure about] has Alpha Centauri A star which is designated a G2V spectral class, the same as the Sun.
    Did it form from the same cloud as our own star did? I don't think we can be sure about that.
    Interesting subject you have raised though and some good points.
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  5. KilljoyKlown Whatever Valued Senior Member

    Until I read that article I never gave much thought to how stars formed in the same stellar nursery, will spread out into the galaxy over billions of years. I think in the back of my mind I just assumed they would kind of stay together in a local group. But that is not even close to the reality of what happens to them.

    The point about all the elements available to new forming star systems still bothers me because from what I've read, many of the heaviest elements require hypernovas to create them, and hypernovas are quite rare. So any star system created in an area with no contributing hypernova would most likely be deficient in many of the heaviest elements. If that is indeed the case I would have to wonder about weather life could even get started let a lone form an intelligent species capable of becoming technological.
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  7. FOLZONI Registered Senior Member

    Those are good points KilljoyKlown.
    More bulk of stars and galaxies are thought to comprise population II stars which have a low metal concentration. One would then think that such galaxies would have few if any planets in them for life relative to Population I bearing entities like spiral galaxies. It seems that only spiral and irregular galaxies can build up adequate supplies of metals by the repeated recycling of material - such as our sun recycling metal-rich material from an older generation of population I stars. Apparently too the metals mix poorly in our galaxy, since there are a class of subdwarf stars presently only detectable in our own galaxy (because such stars are dimmer than the sun though relatively bluish because they lack the metal lines so prominent in the blue end of the spectrum). What I have not yet seen is a 3D map of our galaxy's subdwarfs and how they fit in with the larger picture.

  8. KilljoyKlown Whatever Valued Senior Member

    I see you're new to this forum so I welcome you. It's every time someone talks about finding alien life they always quote the total number of stars in the galaxy as potential places where life might be found and I'm sorry but that's just so far from the truth, that I'm very tired of hearing it. One thing I do know about spiral galaxies is they also have a so called goldilocks zone. To close to the core and the chance of radiation levels being to high to support life goes up dramatically because star counts are much higher and closer together which means almost every system in this area will experience many more super novas close by. Next as the stars extend into the outer regions of the galaxy the numbers go down dramatically and those rare hypernovas that produce the heavy metals are virtually non existent. At this time I'm not very clear how important those missing elements might play in helping life form, but I have to believe it is significant.

    If there's going to be a good distribution of heavy elements in the galaxy where life might be able to start and continue developing for billions of years it most likely will be in the goldilocks zone of the galaxy. The next question I am not very clear about is how large this galactic goldilocks zone is. In other words how many total stars in the galaxy are we now talking about.

    Next I see you mentioned subdwarfs. I read some articles about smaller red stars which at first thought might seem ideal for life to form and have many more billions of years to exist than we do because their sun will last for over maybe over 100 billion years compared to ours which has only about a 10 billion years life cycle. But smaller stars tend to be more active when it comes to sunspots and solar mass ejections. So much more so that any planets in the relatively close to the star goldilocks zone, would be pummeled by radiation that not even a fairly strong magnetic field would be able to provide enough protection for life to develop and evolve over billions of years.

    Given that smaller subdwarf stars greatly out number their larger cousins that would eliminate quite a large percentage of stars even in the galactic goldilocks zone that have a good chance of developing life. So now I have to ask how many stars are in our galaxy that do have a potential for life to develop? I'm guessing not even close to the 200 billion stars that I've heard quoted for the Milkyway galaxy.
  9. FOLZONI Registered Senior Member

    Thank you for your greeting KilljoyKlown.
    It is so good to meet someone so different to the clowns (e.g. the dyspeptic duo Batman & Robin) which dominate other threads.

    That so many stars smaller than our sun (K & M spectral dwarfs) are also highly unstable was evident from odd discoveries concerning variable spectra e.g. one star with a huge starspot covering one third of the surface. Whether all such K & M stars would be unable to engender life on their planets is more difficult to say, especially as their variable metallicity probably creates multiple subtypes of star, some of which could be very stable. There we might find suitable planets for life - perhaps 2-5 million stars in our Milky Way! Of course with the few stars larger than the Sun, more complex life is ruled out by their short life and nova-type activity, which I guess results largely from the CNO cycle being active within them (presuming that the Sun's predicted 3% CNO neutrino contribution is actually non-existent due to the low observed neutrino count).

    I guess too that irregular galaxies, being younger and comprising more large supernova-prone stars, also would be less likely sources for life. What I'd really like to know though is whether elliptical galaxies are eventually recycled into spiral galaxy material - especially when you rightly speak of a 100,000,000,000 year lifespan for smaller dwarf stars!

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  10. KilljoyKlown Whatever Valued Senior Member

    I would be very interested in stars just slightly smaller than our sun with a lifecycle of about 30 billion years. That might be the place to look for a new home for humans, if we can get by the bad times we seem to be heading towards here on Earth. I'm not a big believer in the aliens have visited the Earth scenario, but if there are space fairing species out in our galaxy I'd be very interested in how they got past the rough spots in their history.

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