Yale University | 01 Dec 2010
The Universe Does Think SmallAstronomers have discovered that small, dim stars known as red dwarfs are much more prolific than previously thought—so much so that the total number of stars in the universe is likely three times bigger than realized.
Because red dwarfs are relatively small and dim compared to stars like our Sun, astronomers hadn’t been able to detect them in galaxies other than our own Milky Way and its nearest neighbors before now. As such, they did not know how much of the total stellar population of the universe is made up of red dwarfs.
Now astronomers have used powerful instruments on the Keck Observatory in Hawaii to detect the faint signature of red dwarfs in eight massive, relatively nearby galaxies called elliptical galaxies, which are located between about 50 million and 300 million light years away. They discovered that the red dwarfs, which are only between 10 and 20 percent as massive as the Sun, were much more bountiful than expected.
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In addition to boosting the total number of stars in the universe, the discovery also increases the number of planets orbiting those stars, which in turn elevates the number of planets that might harbor life
Center for Astrophysics | 01 Dec 2010
A substantial population of low-mass stars in luminous elliptical galaxies - PG van Dokkum, C ConroyThe biggest galaxies in the universe are elliptical galaxies. The largest of these hold over one trillion stars according to astronomical census takers, compared to 400 billion in our Milky Way. However, new research shows that elliptical galaxies actually hold five to ten times as many stars as previously believed. This means that the total number of stars in the universe is likely three times bigger than realized.
The hidden stars are known as red dwarfs for their color and small size. Because red dwarfs are small and dim compared to stars like the Sun, astronomers hadn't been able to detect them in galaxies beyond the Milky Way before now. As such, they didn't know how many stars in the universe were red dwarfs.
Scientists used powerful instruments on the Keck Observatory in Hawaii to detect the faint signature of red dwarfs in the cores of eight elliptical galaxies, which are located between about 50 million and 300 million light-years away. They discovered that the red dwarfs, which are only between 10 and 30 percent as massive as the Sun, were much more bountiful than expected.
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galaxies might contain less dark matter - a mysterious substance only detectable due to its gravitational effects - than previous measurements of their masses indicated. Instead, the abundant red dwarfs might contribute more mass than previously calculated.
- Nature (online 01 Dec 2010) DOI: 10.1038/nature09578
arXiv.org > astro-ph > arXiv:1009.5992 > 29 Sep 2010