Astronomers at the International Centre for Radio Astronomy Research may have an answer to a curious late-type spiral galaxy discovered emitting a luminous wake of hydrogen gas as it blazes across the heavens. Though known to scientists for years, galaxy NGC 4569 is located 55 million light-years from our own Milky Way in the Virgo Cluster, where its absence of star-forming gas left many astronomers puzzled. Astronomer Alessandro Boselli and his team at the Laboratoire d’Astrophysique de Marseille in France may have solved the mystery, with their latest findings and speed calculations revealing that the streaking spiral galaxy is just moving way too fast! Using an ultra-sensitive camera called MegaCam on the Canada France Hawaii Telescope, scientists were able to determine that the massive plume of ionized gas is being stripped away as the galaxy clips along at approximately 745 miles per second, creating a radiating cloud some 300,000 light-years across.
“We didn’t have the smoking gun, the clear evidence of direct removal of gas from the galaxy,” said research team member Dr. Luca Cortese. “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. 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.”
Red filaments at the right of the galaxy show the vented hydrogen gas that has been removed. The trailing tail represents 95 percent of the gas reservoir the galaxy needs to feed the birth of new stars.
“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.”
The entire report, published in the journal Astronomy and Astrophysics, can be found here.