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My God, it's full of stars

Staff writer |
How many stars are in the sky? And how many Earths? We know the number is huge, but new and surprising research reveal that there are three times more stars than we thought. And every one of them can have a new Earth in its system.

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Astronomers 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 neighbours 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.

Scientists discovered that there are about 20 times more red dwarfs in elliptical galaxies than in the Milky Way. We usually assume other galaxies look like our own. But this research suggests that other conditions are possible in other galaxies. For instance, galaxies might contain less dark matter, a mysterious substance that has mass but cannot be directly observed, than previous measurements of their masses might have indicated. Instead, the abundant red dwarfs could contribute more mass than realized.

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 harbour life, scientists said. In fact, a recently discovered exoplanet that astronomers believe could potentially support life orbits a red dwarf star, called Gliese 581.

There are possibly trillions of Earths orbiting those stars because red dwarfs they discovered are more than 10 billion years old, and they have been around long enough for complex life to evolve. And that means that the contact with another species is closer than ever.

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