Baby Stars Found in Galactic Center

PASADENA, CALIF. — Baby stars have at last been found in the harsh environment at the center of the Milky Way, astronomers said here this week at the 214th meeting of the American Astronomical Society.

These are "stars that have just ignited their core and they are just starting to produce light. So it is a very early phase in the star formation process," said team member Solange Ramirez of NASA's Exoplanet Science Institute at Caltech.

The heart of our galaxy is an extreme environment, with fierce stellar winds, shock waves and a core supermassive black hole all packed into a region 600 light-years across. While this is but a fraction of the total diameter of the galaxy, which is 100,000 light-years across, the core is stuffed with 10 percent of the gas in the galaxy and a bounty of stars.

Astronomers have long known that stars are born in this chaotic environment, as evidenced by clusters of massive adolescent stars and clouds of charged gas – a sign that new stars are beginning to ignite.

But how they could survive in the region of intense radiation and tremendous gravitational interactions remains something of a mystery, and direct observations of newborn stars have been complicated by the dust that enshrouds them.

"These stars are like needles in a haystack," Ramirez said. "There's no way to find them using optical light, because dust gets in the way."

To get around the obscuring fields of dust, astronomers used NASA's Spitzer Space Telescope.

Ramirez and her colleagues scanned Spitzer mosaics of the galactic center, focusing in on more than 100 candidates of so-called young stellar objects. Viewed from far away, these stars can look much older than their actual age because both types of stars are dusty.

"The old stars and the young stars look pretty much alike," Ramirez said. "You cannot tell them apart."

Examining the light signatures of each star can distinguish between baby and elderly stars. Clouds of certain warm, dense gases are one signature of young stars, for example.

The stars are "still embedded in the molecular cloud where they are being born," Ramirez said.

The three young stellar objects found by Spitzer in the heart of the galaxy are all less than about one million years old (our sun is 4.6 billion years old and considered middle-aged). They are all shrouded in these clouds of gas and dust, which will supposedly eventually flatten into disks and could form planets.

The team plans to look for more baby stars in the galactic center in the future, which could shed light on how these stars manage to form in the intense environment at the heart of the Milky Way.

"By studying individual stars in the galactic center, we can better understand how stars are formed in different interstellar environments," said team member Deokkeun An, also of Caltech.

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