Cosmic strobe may be pair of baby stars

Posted by Kate Taylor

An odd star that flashes like a strobe light may actually be a pair of young stars just a few thousand years old, says a team using the Spitzer and Hubble space telescopes.

Discovered by NASA's Spitzer Space Telescope, LRLL 54361 is a variable object inside the star-forming region IC 348, located 950 light-years from Earth.

Every 25.34 days, it unleashes a burst of light - the most powerful such beacon seen to date. However, it's hidden behind a dense disk of dust.

It now appears that the flashes are caused by periodic interactions between two newly formed stars that are gravitationally bound to each other. The flashes are caused by material suddenly being dumped onto the growing protostars, with a blast of radiation  released whenever the stars get close to each other in their orbits.

This phenomenon, called pulsed accretion, has been seen in later stages of star birth, but never in such a young system or with such intensity and regularity.

"This protostar has such large brightness variations with a precise period that it is very difficult to explain," says James Muzerolle of the Space Telescope Science Institute.

But data from Spitzer has now revealed the presence of protostars, which statistical analysis indicates are no more than a few hundred thousand years old.

NASA's Hubble Space Telescope edthe Spitzer observations and revealed the detailed stellar structure around LRLL 54361, with two cavities above and below a dusty disk. The cavities likely were blown out of the surrounding natal envelope of dust and gas by an outflow launched near the central stars.

Muzerolle and his team hypothesize that the two stars in the center of the dust cloud move around each other in a very eccentric orbit. As they approach one another, dust and gas are dragged from the inner edge of a surrounding disk. The material ultimately crashes onto one or both stars, triggering a flash of light that illuminates the circumstellar dust.