At the Laboratoire d’Astrophysique de Marseille in France, astrophysicists discovered a remarkable tail of star-forming gas approximately 300,000 light years in length coming from a nearby galaxy.
The observations, taken with the Canada France Hawaii Telescope, reveal a plume of hydrogen gas stretching more than five times the length of its source galaxy. Astronomers had observed the galaxy before, known as NGC 4569, and noted a lack of star forming gas but they could not see where the gas had gone – until now. The observations were published in the journal Astronomy & Astrophysics.
“We didn’t have the smoking gun, the clear evidence of direct removal of gas from the galaxy,” said team member Luca Cortese at the International Center for Radio Astronomy Research. “Now, with these observations, we’ve seen a huge amount of gas that creates a stream trailing behind the galaxy for the first time.”
Subsequently, further analysis confirmed the connection between the hydrogen plume and the nearby galaxy: “If you measure the mass of the stream, it’s the same amount of gas that is missing from the galaxy’s disc,” Cortese said.
NGC 4569 is located approximately 55 million light years away in the Virgo galaxy supercluster. You might ask – how did the gas get mysteriously stripped from the galaxy?
According to astrophysicists, the galaxy is travelling along at 1200 kilometers per second and the extreme speed is causing gas to be stripped from the galaxy. It would be like holding a fist full of sand out the window of a speeding car – most of the sand would likely be stripped away depending on how fast you were going.
“We know that big clusters of galaxies trap a lot of hot gas,” Cortese 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.”
“It’s pretty exciting because this was just a pilot and we only targeted the brightest spiral galaxy in the Virgo cluster. 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.”