Scientist provides evidence of black hole in Milky Way

At 33, UCLA's Andrea Ghez already has changed the way astronomers think about starbirth. Now, she has put 25 years of speculation to an end by providing the best evidence yet that a massive black hole sits at the center of the Milky Way. She presented her results at a talk in August at Rutgers University in New Jersey.

Ghez first shook up the astronomical community with her discovery that most newborn stars appear to be twins. Astronomers have known since the 1970s that roughly half the stars in the universe come in pairs. What was unclear was whether they were born double, or teamed up two by two later in their evolution, like animals on Noah's ark.

While still a graduate student, Ghez found that the youngest infants in the stellar family are more likely than older stars to be twins. That means, she said, that stars are probably born double.

The discovery has posed a major problem for astronomy because it contradicts the prevalent theories of how stars form. The theories describe a single star condensing out of a glob of interstellar gas. As the gas collapses under the force of gravity, a star is born. Those theories do not provide any good mechanism to explain the formation of double stars.

"The (current theory) very nicely produces our sun and planets," she said. "But it only produces single stars. Nature produces doubles. Single stars might be harder to find than we thought."

Her discovery also raises the question of what happens to all the missing partners of the solitary stars like our sun? "That, we don't understand," Ghez said.

It is to figure out puzzles of this sort that astronomers come to Keck.

But this sky-high lookout comes with a downside. At 13,800 feet, there's only half the normal supply of oxygen, and human brains don't function at full speed.

"I don't think as well up here," Ghez said. "If I'm working on the instrument, conversations in the background annoy me. I can't do two things at once."

Adding to the problem, the astronomers don't get much sleep. At dawn, they'll drive downhill to their mid-mountain base, turning in for some rest just after breakfast. They wake around 2 p.m., analyze data and get ready for the next night's work. Dinner at 4. Then back to the summit.

"You put together a diverse group of people," Ghez said. "And if someone (makes you angry), you can't go outside to cool off." Not when the temperature on the summit is well below freezing on the balmiest nights.

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