Pic of the Week: The Jellyfish Galaxy

Image (Credit): The massive galaxy JO204. (NASA)

This week’s image is from the Hubble Space Telescope. You are looking at JO204, also called the “jellyfish galaxy” because of its tendrils. It is about 600 million light-years away. It is an impressive sight.

Here is a little more on the galaxy from NASA:

While the delicate ribbons of gas beneath JO204 may look like floating jellyfish tentacles, they are in fact the outcome of an intense astronomical process known as ram pressure stripping. Ram pressure is a particular type of pressure exerted on a body when it moves relative to a fluid. An intuitive example is the sensation of pressure you experience when you are standing in an intense gust of wind – the wind is a moving fluid, and your body feels pressure from it. An extension of this analogy is that your body will remain whole and coherent, but the more loosely bound things – like your hair and your clothes – will flap in the wind. The same is true for jellyfish galaxies. They experience ram pressure because of their movement against the intergalactic medium that fills the spaces between galaxies in a galaxy cluster. The galaxies experience intense pressure from that movement, and as a result their more loosely bound gas is stripped away. This gas is mostly the colder and denser gas in the galaxy – gas which, when stirred and compressed by the ram pressure, collapses and forms new stars in the jellyfish’s beautiful tendrils.