Astronomers try to find
mystery of galactic core

They will share their observations
at a Big Island conference

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By Helen Altonn
haltonn@starbulletin.com

More than 100 astronomers will meet on the Big Island next month to try to unravel the mysteries of what is believed to be a super-massive black hole at the center of the Milky Way galaxy.

"We have been studying this for three decades now," said Peter Michaud, Gemini Observatory spokesman.

"We think we have a pretty good understanding of how massive the object must be there."

Yet not everyone agrees that it is a massive black hole, he said.

"Some scientists say it could be some other kind of a massive object."

Most Mauna Kea telescopes at one time or another are doing something related to the galactic center, Michaud said.

"One of the big questions in astronomy is what happens near centers of normal galaxies like our Milky Way."

As the closest galaxy, it can provide clues about the cores of other galaxies, but "a lot of stuff is in the way between us and the center," Michaud said.

Observations must be in infrared to penetrate gas and dust blocking the view of optical wavelengths, he said.

In optical light, it is estimated scientists can only probe about 10 percent of the estimated 25,000 light-years to the galactic core.

Tom Geballe, Gemini senior scientist and chair of the conference's organizing committees, said, "It is only recently that astronomers have had the tools necessary to understand the center of our galaxy with any certainty, and the subject has attracted a very diverse group of scientists from theoreticians to astronomers studying light all along the electromagnetic spectrum."

Using the latest infrared, radio and X-ray sensitive instruments on ground-based telescopes and earth-orbiting observatories, scientists "are able to coax the core of our galaxy into revealing its secrets," the Gemini astronomers said.

Chandra X-Ray Observatory images also have provided a mosaic of the Milky Way's turbulent galactic center showing it has escaping multimillion-degree gas and hundreds of white dwarf stars, neutron stars and black holes.

The conference, Nov. 3-8 at the Keauhou Beach Resort near Kailua-Kona, is called "The Central 300 Parsecs." Parsecs is a way of measuring distance, equivalent to a little more than three light-years, Michaud said.