Young stars show 'growing pains'

GREENBELT, Md., Feb. 29 (UPI) -- Astronomers using a European space telescope say they've seen changes in young stars in the Orion nebula suggesting a turbulent journey to stellar adulthood.

Data from the European Space Agency's Herschel Space Observatory, combined with observations from NASA's Spitzer Space Telescope, indicate stars strung across the telescope images are rapidly heating up and cooling down, a NASA release said Wednesday.

In an image of a portion of the Orion nebula, the telescopes' infrared vision reveals a number of embryonic stars, hidden in gas and dust clouds, at the very earliest stages of their evolution.

As clumps of this gas and dust come together, they form a warm glob of material that in several hundred thousand years will gather enough material to trigger nuclear fusion at their cores and blaze into stardom, astronomers said.

Astronomers noticed several of the young stars varied in their brightness by more than 20 percent over just a few weeks.

This puzzled the astronomers, who said cool material emitting the infrared light must be far from the hot center of the young star, likely in the outer disk or surrounding gas envelope, and should take years or centuries to spiral closer in to the growing starlet, rather than mere weeks.

"Herschel's exquisite sensitivity opens up new possibilities for astronomers to study star formation, and we are very excited to have witnessed short-term variability in Orion protostars," said Nicolas Billot, an astronomer at the Institut de Radioastronomie Millimetrique in Grenada, Spain.

"Follow-up observations with Herschel will help us identify the physical processes responsible for the variability."