M87

StarDate: May 13, 2009

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The galaxy known as M87 is a monster. The numbers are staggering, with zeroes stacked upon zeroes. The galaxy spans a half-million light-years or more. Its heart is dominated by a black hole that's billions of times more massive than the Sun. And it's home to more than a trillion stars -- that's a one followed by 12 zeroes.

While our own galaxy is shaped like a pancake, M87 looks like a fat, fuzzy football. Its stars orbit the center of the galaxy in random directions. That suggests that M87 formed when several smaller galaxies merged to make a single giant agglomeration of stars.

The scenario makes sense, because M87 is near the center of a vast cluster of galaxies. The galaxies are crowded close together, and they frequently interact with each other. M87 is the dominant member of the cluster, so most of the other galaxies orbit around it.

The mergers that built M87 also built up its central black hole. As the galaxies came together, their central black holes merged to make a bigger one. Recent observations by astronomers at McDonald Observatory suggest the black hole is about seven billion times as massive as the Sun -- one of the largest black holes yet discovered.

M87 is at the center of a triangle of three bright points of light. The stars Arcturus and Spica are in the east an hour or two after sunset, with the planet Saturn to their upper right. You need a telescope to spot this galactic monster.

More about M87 tomorrow.

Script by Damond Benningfield, Copyright 2009

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