How does star-making start? For first time, scientists might get a glimpse.
Scientists have yet to see a star form all on its own – away from the influence of surrounding stars. Now, researchers say they might have found a candidate.
Long before a star is a gleam in anyone's telescope, it begins its ascent to stardom as a cold fragment in a vast cloud of gas and dust.Skip to next paragraph
In Pictures Where stars form
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A team of astronomers reports capturing one of these stellar embryos in a small corner of an enormous molecular cloud some 600 light-years away in the constellation Perseus.
If the team's interpretation of its data holds up to further scrutiny, the region would open a window on a critical, poorly understood stage of a star's evolution.
Much of what astronomers have learned about star formation comes from studying molecular clouds where stars already have formed. These clouds continue to produce relatively dense clumps of dust and gas that will become another generation of stars. But the formation and evolution of these newcomers can be heavily influenced by their already burning siblings.
For example, young stars burn hot and so give off strong stellar winds, which can sweep surrounding regions clean of other gas clumps. When there are clusters of young stars, this process becomes especially powerful. Even a star ending its life in an enormous explosion called a supernova can stifle star formation nearby because of the material the blast ejects. On the other hand, at longer distances, stellar winds or a shock wave from a supernova can trigger clumping.
Pristine stellar nursery
These processes make it difficult to answer the question: What processes influence the first stars to form in a cloud? The segment of the Perseus molecular cloud the team studied hosts no other stars, providing a pristine stellar nursery for testing hypotheses about these initial influences.
“Some stars have to form first for those later triggers to develop,” says James Di Francesco, an astronomer at the University of Victoria in British Columbia and a member of the team reporting the results in an upcoming issue of the journal Astronomy & Astrophysics.
“What's exciting about this discovery is that we see what we think is a clump of gas that's formed within a molecular cloud that is further fragmenting into individual pieces – forming a first generation of cores” available to become stars, he says.
“It's a rare find,” noted Sarah Sadavoy, a graduate student at the University of Victoria and the study's lead author, in a prepared statement.
She and her colleagues note that in 2010 another group reported the discovery of a candidate region for still-gathering fragments – the even denser sections of a gas clump that can eventually become stars – but that team was unable to detect any individual fragments.
The region of the Perseus cloud Ms. Sadavoy and colleagues studied is known as Perseus B1-E. It's one of five prominent regions of gas and dust in the cloud dense enough to act as a large-scale stellar nursery. Two of the other regions host either evolved stars or so-called young stellar objects, which are much farther along on their path from cold clump to cosmic beacon.