At almost 4.5 million miles per hour, spiral galaxy ESO 137-001 is hurtling through other galaxies in the Norma cluster. The intergalactic gas in the cluster is a scorching 180 million degrees Fahrenheit. Caught by Hubble’s Wide Field Camera 3 (WFC3), the images come from 200 million light-years away. Observed by NASA, the spiral galaxy is being torn apart by a process known as ram pressure stripping.
Ram pressure stripping is a drag force that results from objects moving through fluid. Though it does not seem apparent that a galaxy would be plowing through anything, let alone a fluid, in this case the fluid is actually the superheated intergalactic gas. The forces exerted and the resultant drag is stripping galaxy ESO 137-001 of much of its gases. The galaxy itself remains intact due to the binding forces of the stars’ gravity.
Astronomers are gaining a better understanding of how galaxies evolve through observation of this ram pressure stripping. In the case of galaxy ESO 137-001, much of the cold gases essential for star formation are currently being stripped away. This will leave the spiral galaxy effectively unable to form new stars. While galaxy ESO 137-001 itself will be unable to spawn new stars, the streaks it is leaving behind are a hotbed of young stars.
The spiral galaxy is part of the Norma Cluster which is a cluster of galaxies in the center of a massive region of space known as the Great Attractor. The Great Attractor, located 200 million light-years from the Milky Way, has a strong gravitational pull which is slowly hauling both our galaxy and others towards itself. While in cosmic standards the Norma Cluster is nearby, it took a good deal of technology to be able to view it. The cluster is obscured by a smog of cosmic dust because it lies near the plane of the Milky Way. Using the Hubble WFC3, NASA was able to observe inside the Norma Cluster and document how a galaxy can be torn apart by ram pressure stripping.
This is not the first time that NASA and the Hubble Space Telescope have captured images of ram pressure stripping in galaxies. Two galaxies from the Virgo Cluster were imaged back in 2007 with the Advanced Camera for Surveys (ACS) prior to Hubble’s power failure. The galaxies are known as NGC 4522 and NGC 4402. Much like the newly observed ESO 137-001, galaxy NGC 4522 is also a spiral galaxy. NGC 4522 is located about 60 million light-years away. Mission 4, undertaken by astronauts in May 2009, was able to restore ACS so the captured images could be retrieved.
Astronomers, scientists, and NASA continue to study and observe the images and data of the galaxies being torn apart by ram pressure stripping in the hopes of better understanding how a galaxy is formed. The new data and images from Hubble’s WFC3 will build upon the information previously obtained. A great deal can be told about the environments present in the heart of galaxy clusters, the formation of new stars, and the fate of galaxies like NGC 4522, NGC 4402, and now, ESO 137-001.
By Dee Mueller