A Galactic Tale about a Galactic Tail

Galaxy NGC 4569 is a spiral galaxy that is part of the Virgo cluster, around 55 Million light years distant.  Like any other spiral galaxy, we can learn about its motion through the cluster, the properties of its stellar population, and how quickly its converting gas and dust to stars.  But this galaxy has an interesting property, it’s missing a lot of gas.  For years, astronomers have had ideas about where the gas has gone, and with new data from the Canada-France-Hawaii Telescope (CFHT), they now have the answer.

Credit: Image courtesy of International Centre for Radio Astronomy Research (ICRAR)

The gas is being stripped off of the galaxy, and is now trailing it in a 300,000 light year long streak.  The amazing part is that the amount of gas measured in the trail perfectly matches the missing gas in the galaxy.  But how is it being stripped away?

Because NGC 4569 is part of the Virgo cluster, it lies in a harsh environment where the intergalactic medium is filled with hot gas.  As the galaxy moves through this gas, it’s as if it’s feeling a constant ‘wind’ that continually strips away it’s molecular hydrogen.  The hydrogen becomes part of the intergalactic gas, and leaves a noticeable trail behind it.

This could be the first of many galaxies that leave a trail behind as they move through a cluster, and may provide a mechanism for bringing reservoirs of hot gas to a cluster in the first place.  As usual – time and science will tell.


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