Big Baby Star Spotted in Dusty Womb

The first evidence is found in a 20-year debate over whether massive stars form the same way as smaller stars.

THE GIST

Scientists find the first example of a big young star still wrapped in a dust disk.

The image resolves the question of whether it's possible for big stars to form the way smaller, sun-sized objects do.

Scientists have taken a picture of a huge baby star cocooned in a disk of dust, the first observational evidence in a 20-year debate about whether massive stars form the same way as smaller, sun-like stars.

In the case of IRAS 13481-6124, located about 10,000 light-years away in the constellation Centaurus, the answer is unequivocally yes, say researchers who combined the light-gathering power of an array of telescopes to come up with an imaging technique sharp enough to distinguish the dust disk from its embedded star.

This virtual instrument is 10 times more sensitive than stand-alone telescopes in use today. Its resolving power is equivalent to seeing the head of a screw on the International Space Station from 225 miles below on the ground.

The research appears in this week's issue of Nature.

Siphoning matter from a dust disk is the way smaller stars like the sun got their start. Scientists didn't know if big stars, 10 to 20 times more massive than the sun, could form the same way. Computer models and simulations show that a massive star's powerful radiation might keep dust at a distance. The most popular alternative theory is that small, developing stars bump into each other and combine to form more massive young stars.

"It was a problem to explain about how high-mass stars form," lead researcher Stefan Kraus, with the University of Michigan, told Discovery News.

Astronomers are on the hunt for other big baby stars still wrapped in dust cocoons, but massive young stars are relatively rare, quite distant and typically clumped together so that it is difficult to pick out individual objects in the tumultuous, complicated environment.

"For now, we can only talk about this object, where we found a disk, but it means in general it is possible for a disk to exist around stars with these properties," Kraus said.

IRAS 13481-6124 is about 60,000 years old and roughly 20 times more massive than our 4.6 billion-year-old sun.

"Having one example certainly moves us forward, but the debate  probably won't be settled for a very long time," added University of Florida astronomer Peter Barnes. "It's conceivable that both processes (for forming high-mass stars) occur, though probably one does dominate."