Messier 90, the brightest galaxy in the Virgo Cluster, has a 300,000 light-year-long tail of diffuse ionized gas flowing from it, says an international team of astronomers.
Pseudo-color image of Messier 90 (NGC 4569); north is up, east left. Image credit: A. Boselli et al.
Messier 90, also known as M90 and NGC 4569, is a giant spiral galaxy located in the constellation Virgo, approximately 53.8 million light-years away.
This galaxy is a member of the Virgo Cluster, a group of about 1,300 — and possibly up to 2,000 — member galaxies.
“Astronomers noticed long ago that Messier 90 contained less gas than expected but they could not see where it had gone,” said Dr. Luca Cortese of the University of Western Australia’s International Centre for Radio Astronomy Research.
“We didn’t have the smoking gun, the clear evidence of direct removal of gas from the galaxy.”
“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.”
According to Dr. Cortese and his colleagues Messier 90 is traveling through the Virgo Cluster at about 1,200 km a second, and it is this movement that is causing the gas to be stripped from the galaxy.
“We know that big clusters of galaxies trap a lot of hot gas. 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,” Dr. Cortese said.
The discovery, published in the journal Astronomy & Astrophysics, was made when the team used a super-sensitive camera on the Canada France Hawaii Telescope to observe Messier 90 for longer than ever before.
Dr. Cortese said it could be the first of many galaxies found to have long tails of gas extending from them.
“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.”
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A. Boselli et al. 2016. Spectacular tails of ionized gas in the Virgo cluster galaxy NGC 4569. A&A 587, A68; doi: 10.1051/0004-6361/201527795
