June 10, 2008

In Today's One Minute Astronomer...

M87: Monster Galaxy in Virgo

There's nothing subtle about the giant elliptical galaxy M87… no faint spiral structure or dust lanes to see at all. The excitement lies in contemplating the stupendous size of this monster galaxy and the scope of the violent physical processes going on in its core.

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Join master science writer Timothy Ferris as he tours the known universe and reveals the technological revolution sweeping amateur astronomy. One of the most elegant and poetic books about stargazing ever written. Learn more...

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The Basics

• You can find M87 in Virgo on a line between Vindemiatrix in Virgo and Denebola in Leo, about halfway between the two. At magnitude 8.6, it's visible in a 3” or larger scope.

• This giant galaxy spans a diameter of 120,000 light years, about the same as the Milky Way. But M87 is a spheroid, not a flat spiral. So it contains far more stars… as many as 2.7 trillion solar masses by some estimates.

• M87 lies at the heart of the famous Coma-Virgo cluster of galaxies, a collection of some 2,000 galaxies about 60 million light years away.

A Deeper Look

•Aside from its immensity, M87 is known for a needle-like jet that's blasted 5,000 light years into intergalactic space, presumably by a disturbance caused by a black hole in its core. The central black hole is monstrous… with an estimated mass of 2-3 billion suns!

• Keen observers under perfect seeing conditions can see the jet in large scopes. And I mean large, as in 20” to 30” aperture!

• M87 also boasts a spectacular collection of globular clusters, up to 15,000, compared to the Milky Way's count of 200 or so.

• Radio astronomers see the center of M87 as a strong radio source called “Virgo A”. Again, the source of the radio waves is the violent activity in and around the core.

Good To Know

Astronomers measure the speed of M87's jet to be 4-6 times the speed of light… an impossibility according to known physical laws. This measurement is an optical illusion caused by the orientation of the jet which moves towards us at close to light speed. So no physical laws are violated.

Personal View

M87 is a wonderful object to show beginners with keen imaginations. At first, they are disappointed by the faint smudge in the eyepiece. But tell them they're looking at TWO TRILLION stars at one time and they start to understand why it's worth getting into stargazing.