杏吧原创

Donut feast may explain giant stars

A long-standing mystery over how massive stars are born could be cleared up thanks to the observation of the birth of such a sun
Stars may grow to extreme masses by accumulating dust from a donut-like disc around them (Illustration: Bill Saxton/NRAO/AUI/NSF)
Stars may grow to extreme masses by accumulating dust from a donut-like disc around them (Illustration: Bill Saxton/NRAO/AUI/NSF)

A long-standing mystery over how massive stars are born could be cleared up thanks to the first observation of the birth of such a sun.

Astronomers know low-mass stars like our sun form by gathering material from gas clouds like those in the Eagle nebula (above). But that can鈥檛 explain how stars bigger than about 10 times the mass of the sun could form without their intense radiation blasting away surrounding material before they reach full size.

One solution is that big stars form from doughnut-shaped gas clouds in which stellar radiation escapes in beams along the stars鈥 poles. An alternative suggestion is that they could form when mid-sized stars collide, but until now there was no observational evidence either way.

Now Maria Beltr谩n at the University of Barcelona in Spain and her colleagues have observed the birth of a large star in a rotating doughnut-shaped cloud, with matter falling into a young star core and an outflow of stellar radiation from the poles (Nature, vol 443, p 427).

鈥淣obody had seen all three of these features at the same time,鈥 says Beltr谩n. This clearly supports the gas cloud theory of how high-mass stars form, she says. 鈥淏ut the collision theory may still be true for star formation in other places,鈥 she adds.