The Milky Way’s center of attention

Posted by Daniel Pendick
on Wednesday, December 10, 2008

300Did a parent, boyfriend/girlfriend, spouse, supervisor, etc., ever say to you in an argument, “You’re not the center of the universe, you know!”

Well, sorry to disappoint, but you’re not the center of the galaxy either.

That honor belongs to a black hole that weighs between 4,250,000 and 4,370,000 times the Sun’s mass and lies somewhere between 26,028 and 27,169 light-years from Earth.

How do I know? Because German astrophysicist Reinhard Genzel and his team at the Max-Planck-Institute for Extraterrestrial Physics in Garching near Munich recently reported the results of a 16-year study tracking the orbits of 28 speedy stars as they zip around the galactic center. The only object with enough mass to account for the stars’ orbits is a black hole.

We knew that black hole was there, but estimates of its mass and distance varied. In an article I edited last year, I said “3 to 4 million solar masses.” Now we have a nice, solid number for each. Genzel won the prestigious Shaw Prize in Astronomy for 2008 for this research.

Nice, solid numbers make science editors sooooo happy. No longer will awkward phrases like “according to scientists’ best estimate yada yada yada” appear in my work. I can just say “about 27,000 light-years” and “about 4 million solar masses.” In fact, I just did — this morning, as I was putting the final touches on a story mentioning the Spitzer Space Telescope’s discoveries about the Milky Way.

This study appears in the December 20 issue of The Astrophysical Journal.

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