February 22, 2016
Astronomers discover 300,000-light-year-long gas tail stretching from galaxy
Astronomers have found an extraordinary trail of gas greater than 300,000 light years across originating from a nearby galaxy called NGC 4569, according to a report in Astronomy & Astrophysics.
The tail is comprised of hydrogen gas, the material new stars are born from, and is five times longer than the galaxy itself.International Centre for Radio Astronomy Research astrophysicist Luca Cortese, who is part of the study team, said researchers have known that the galaxy NGC 4569 held less gas than expected but they couldn't see where it went.
"We didn't have the smoking gun, the clear evidence of direct removal of gas from the galaxy," he said in a statement. "Now, with these observations, we've seen a huge amount of gas that creates a stream trailing behind the galaxy for the first time.
"What's very nice is that if you measure the mass of the stream, it's the same amount of gas that is missing from the galaxy's disc,” Cortese added.
NGC 4569 is located in the Virgo cluster, 55 million light years away, and moving through the cluster at approximately 750 miles a second. Cortese said this motion strips gas from the galaxy.
"We know that big clusters of galaxies trap a lot of hot gas," he said. "So when a galaxy enters the cluster it feels the pressure of all the gas, like when you feel the wind on your face, and that pressure is able to strip matter away from the galaxy."
The study team's finding was made when they used a super-sensitive camera on the Canada France Hawaii Telescope to observe NGC 4569 for more time than ever before.
Cortese said NGC 4569 might be the first of many galaxies discovered to have long tails of gas stretching out from them.
"It's pretty exciting because this was just a pilot and we only targeted the brightest spiral galaxy in the Virgo cluster," he said. "We were amazed by what we got… this is really promising because it means it's very likely we'll find similar features in many other galaxy clusters."