Monday, January 10, 2011

Astronomers' Say 3 Times as Many Stars as Thought!

             Scientists have recently discovered that the number of stars in the universe had been seriously undercounted, and they estimated that there could be three times as many stars out there as had been thought. The counting, of cooler, dim dwarf stars in certain galaxies gives astronomers’  an understanding of how galaxies formed and grew over the eons.
The conundrum is that astronomers cannot actually count the dwarf stars, which have masses less than a third of that of our Sun, in galaxies outside the Milky Way. So instead, they counted the brighter Sun-like stars and assumed that there were about 100 unseen dwarfs for each larger Sun-like star, as is the case in the Milky Way.
Yet obviously not every galaxy looks like the Milky Way, with its spiraling pinwheel arms. Some are blobby and elliptical, and it was just an assumption that the distribution of stars in other shaped elliptical galaxies is the same as in the Milky Way.


Astronomers are now taking an innovative approach to counting what they formerly could not see. Because the dwarfs are cooler, the fingerprint of certain colors they emit and absorb is different from that of larger stars. While they could not see individual stars, the astronomers could calculate the number of dwarfs required to produce the telltale color fingerprint they detected in the light coming from the whole galaxy.

They found that in eight elliptical galaxies, the ratio of dwarf stars to Sun-like stars was 1,000 or 2,000 to 1, rather than the 100 to 1 in the Milky Way. A typical elliptical galaxy, thought to consist of about 100 billion stars, would have one trillion or more stars. Ellipticals account for about a third of all galaxies, leading to the new estimate of at least three times as many stars over all.
Basically what this mean is that Astronomers have had to abandon this notion of using the Milky Way as a template for the rest of the universe.  Also if the findings are correct, an undercount of dwarfs would mean astronomers have underestimated the masses of galaxies, and that could mean that galaxies developed much earlier and faster than currently thought. I think it’s pretty interesting and important when papers like this are published, and it reminds us how much we need to continue working to expand our knowledge of the universe.

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