Galactic pyrotechnics

WAIKOLOA, Hawaii » One of the most mysterious and exotic objects in the galaxy is poised to spit out some information.

A huge gas cloud, roughly three times the mass of Earth, is headed toward the black hole at the center of the Milky Way, scientists say. It should arrive by this summer.

And if it does, astronomers expect fireworks.

Not the kind we can see with the naked eye, but spectacular nonetheless from a cosmic point of view.

"There is a huge amount of excitement in our community about what might come this summer," says Andrea Ghez, an astronomer and director of the Galactic Center Group at UCLA.

If the cloud falls into the grip of the black hole, it will be "completely shredded," Ghez said in a presentation last week at the Fairmont Orchid hotel in South Kohala. "The black hole is going to see a fresh dose of material that could put it into a different state."

As it gulps gas, the black hole is expected to emit radiation — what University of Hawaii astronomer Guenther Hasinger compares to a burp after a meal — across a range of wavelengths including infrared and X-rays.

"More than 30 programs have been approved for this summer alone to watch this event," Ghez said at a science forum Thursday convened to mark the 20th anniversary of the Keck Observatory on Mauna Kea. "This may be the most observed observational event in recent history."

The Keck Telescope will be part of the worldwide observations, Hasinger, director of the UH Institute for Astronomy, confirmed Monday.

Meanwhile, Ghez and colleagues in Illinois on Monday released stunning animation showing stars in close orbit around the galaxy’s supermassive black hole.

The video is based on observations over the past 18 years of the very fast, very short orbits of stars under the influence of the black hole’s mass, estimated to be 3.7 million times that of our sun.

Ghez’s "favorite star," called SO-2, completes one orbit every 16 years. Another, SO-102, orbits the black hole every 11.5 years, the shortest period found to date, Ghez and colleagues reported last year.

The top speed: 26.8 million mph.

"This gives us really great evidence that very exotic objects exist in the universe," said Ghez, whom Time last year named one of the 25 most influential space scientists.

It was largely through her persistent efforts that most astronomers now accept that a black hole occupies the galactic center.

"There were plenty of people who were willing to come out and say, ‘I’ve got other ideas about what this should be,’" she recalled in her talk. "That means, of course, you really need to keep going."

Her first research proposal into the topic, in 1994, was turned down because the astronomy community thought she was barking up the wrong tree.

That has changed dramatically.

In 2012, Ghez became the first woman to win the prestigious Crafoord Prize in Astronomy from the Royal Swedish Academy of Sciences, which cited her observations on the galactic center. She shared it with Rhein­hard Genzel of Germany’s Max Planck Institute.

Ghez theorizes that the black hole and the Milky Way have an ancient and "synergistic" relationship.

"It really is a great opportunity to study the role of black holes in the formation and evolution of the galaxy," she said. "And it’s only been possible with high-resolution imaging on 10-meter-plus telescopes."

The Keck has twin telescopes, each with a 10-meter-diameter primary mirror, and each fitted with an adaptive optics system that uses a laser guide star to compensate for the blur of the atmosphere.

Black holes are objects so massive that not even light can escape their gravitational tug.Ghez posits that black holes are likely common at the center of other galaxies.

"If our galaxy has a supermassive black hole — and we are an ordinary, garden-variety galaxy, nothing special about us — the inference from that is that all galaxies harbor supermassive black holes," she said.

Many are "dormant, or quiet," she added. "Or I sometimes like to view them as black holes on a diet."

For the Milky Way’s dark companion, that hunger spell could be about to end.