A team of astronomers based at The University of Toledo has discovered an outburst from a star thought to be in the earliest phase of its development. The eruption reveals a sudden accumulation of gas and dust by an exceptionally young protostar known as HOPS 383.

Led by Dr. Tom Megeath, associate professor of physics and astronomy, the team used data from orbiting observatories, including NASA’s Spitzer Space Telescope, and ground-based facilities to research the formation of stars similar to the Sun.

HOPS 383 is located about 1,400 light-years away, near the well-known Orion nebula. The region constitutes the most active nearby “star factory” and is home to a multitude of young stellar objects.

Stars form within collapsing fragments of cold gas clouds contracting due to gravity. In the center of the cloud, a small protostar forms surrounded by a dusty orbiting disk. Astronomers call this a Class 0 protostar. The disk grows as gas from the cloud continues to fall, and the disk in turn “feeds” the protostar. Astronomers monitor protostars to see if the disk feeds the protostar in little bites or big gulps, because this can have big consequences for the formation of stars and planets. HOPS 383 appears to have just taken a big gulp.

“HOPS 383 is the first outburst we’ve ever seen from a Class 0 object, and it appears to be the youngest protostellar eruption ever recorded,” said William Fischer, a NASA Postdoctoral Program Fellow at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Fischer attended UT as an undergraduate from 1997 to 2001 and returned as a postdoctoral fellow from 2008 to 2013.

The Class 0 phase lasts roughly 150,000 years, and means that most of the star-forming material is still in a dusty envelope surrounding the star, and has not yet been consumed by the star.

The eruption was first discovered in 2014 by astronomer Emily Safron, shortly after her graduation from UT. Under the supervision of Megeath and Fischer, she had just completed her senior thesis comparing the decade-old Spitzer Orion survey with 2010 observations from NASA’s Wide-field Infrared Survey Explorer (WISE) satellite. She had already run through the data several times without finding anything new but with her senior thesis completed, she decided to take the extra time to compare the images by eye.

That’s when she noticed HOPS 383’s dramatic change.

“This beautiful outburst was lurking in our sample the whole time,” Safron said.

Megeath’s team also identified more than 300 protostars in the Orion complex using NASA’s Spitzer Space Telescope. A follow-on project using the European Space Agency’s Herschel Space Observatory, called the Herschel Orion Protostar Survey (HOPS), studied many of these objects in greater detail.

Upon Safron’s discovery, the team gathered additional Spitzer data, Herschel observations and images from ground-based infrared telescopes at the Kitt Peak National Observatory in Arizona and the Atacama Pathfinder Experiment in northern Chile. Their findings were published in the Feb. 10 edition of the Astrophysical Journal.

“The immediate impact for star formation studies is that astronomers are going to have to revisit our theories to explain how such a young object can have this kind of outburst,” Fischer said.

Tags: College of Natural Sciences and Mathematics