March 2000

SCIENCE:
Surveying the sky

Astronomers have long suspected that our home galaxy, the 100-billion-star Milky Way, has a gluttonous appetite for its smaller neighbors, and research by Heidi Newberg and her colleagues in the Sloan Digital Sky Survey has confirmed it.

“The Milky Way is accreting small galaxies. We’re eating
galaxies all the time,” said the associate professor of physics at Rensselaer Polytechnic Institute.

The Sloan Survey is the most ambitious astronomical survey ever undertaken. It will map in detail one-quarter of the sky, and determine the positions and brightness of more than 100 million celestial objects.

Newberg came to Rensselaer after seven years at the Fermi National Accelerator Laboratory. She remains a principal software writer with the Sloan project, which she described as “a very large survey of the sky, a cosmic census, 10,000 square degrees. That’s one-quarter of the sky.”

Newberg and other Fermilab scientists constructed the Sloan’s data acquisition system to process the expected 20 terabytes of data to be accumulated during its five-year span. The survey has already discovered four of the five most distant quasars ever identified. Researchers also located the second known methane brown dwarf, an obscure object smaller than a star and larger than a planet.

In addition, Sloan researchers have learned that the unseen dark matter—or halos—that surround galaxies are about twice as large as previously believed.

“The idea is to get a million galaxies, 100,000 quasars, tens of thousands of galactic stars. It’s a big, big project,” Newberg said.

CONTACT: Theresa Bourgeois, (518) 276-2840, bourgt@rpi.edu

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