MSU professors watch for star development
Megan Donahue is taking her sights out of East Lansing and setting them 219 million years away.
The MSU professor of physics and astronomy is part of a team of researchers from across the globe keeping an eye on an unusual, two-pronged, star-creating tail of gas first discovered three years ago.
The 200,000 light-year-long tail is forming stars outside the confines of a galaxy, where star formation usually takes place.
“This system is showing us star formation happening in a place where most of us thought it shouldn’t,” Donahue said. “We have here an example of when scientists are delighted to be wrong.”
Tails such as the one discovered by the team are not a phenomenon by themselves, Donahue said. Tails similar to the one discovered are made of streams of gas being pulled out of a galaxy. What makes the tail unique is the fact that star formation usually is thought to occur inside cold molecular clouds, commonly found in the disks of spiral galaxies.
The phenomenon first appeared three years ago during observations using multiple telescopes. One of the telescopes, a satellite currently in orbit called the Chandra X-ray Observatory, helped the researchers examine the tail.
Donahue said one of the team’s most recent observations was the cloud’s has two tails, which will present a new set of questions to be answered.
The researchers, who published a paper in the Jan. 10 edition of The Astrophysical Journal, are developing theories as to why there are two tails and will use computer software to find answers, said Mark Voit, a professor of physics and astronomy who also works with the team.
Donahue said current computer software might not be adequate to test all the group’s theories, such as one that hypothesizes magnetic forces are acting on the tail.
“Some of us think that magnetic fields may play a role in the behavior of the gas, but the computer simulations that include magnetic fields are not yet realistic enough to say one way or the other,” she said.
Ming Sun, a research associate in the Department of Astronomy at the University of Virginia who previously worked at MSU, said the team’s findings are significant because they imply stars are able to form outside of galaxies.
It also could mean black holes occur outside galaxies because they are formed from massive stars that explode.
“Astronomers once thought that the stars between galaxies are all old stars, directly pulled out from galaxies by gravity,” Sun said. “This work implies that many stars between galaxies can actually form there.”