Astronomer were surprised to find two distinct "tails" found on a long tail of gas that is believed to be forming stars where few stars have been formed before.

"The double tail is very cool - that is, interesting - and ridiculously hard to explain," said Donahue, a professor in MSU's Department of Physics and Astronomy. "It could be two different sources of gas or something to do with magnetic fields. We just don't know."

"This system is really crazy because where we're seeing the star formation is well away from any galaxy," Donahue said. "Star formation happens primarily in the disks of galaxies. What we're seeing here is very unexpected."

Michigan State University astronomer Megan Donahue was part of an international team of astronomers that viewed the gas tail with a very long, new observation made by the Chandra X-ray Observatory and detailed it in a paper published this month in the publication Astrophysical Journal.

This gas tail was originally spotted by astronomers three years ago using a multitude of telescopes, including NASA's Chandra X-ray Observatory and the SOuthern Astrophysical Research telescope, a Chilean-based observatory in which MSU is one of the partners. The new observations show a second tail, and a fellow galaxy, ESO 137-002, that also has a tail of hot X-ray-emitting gas.

How these newly formed stars came to be in this particular place remains a mystery as well. Astronomers theorize this gas tail might have "pulled" star-making material from nearby gases, creating what some have called "orphan stars."

"MSU's Megan Donahue was part of an international team of astronomers that viewed this rare double-tailed gas cloud. (Credit: Photo courtesy of the Chandra X-Ray Observatory)"

Source: Michigan State University