Yale University | 2015 July 27
[img3="The leading side of the disk shows the effects of strong ram pressure.Astronomers have long known that powerful cosmic winds can sometimes blow through galaxies, sweeping out interstellar material and stopping future star formation. Now they have a clearer snapshot of how it happens.
(Image: NASA, ESA, and Roberto Colombari)"]http://news.yale.edu/sites/default/file ... Binset.jpg[/img3][hr][/hr]
A Yale University analysis of one such event in a nearby galaxy provides an unprecedented look at the process. The research is described in the Astronomical Journal.
Specifically, Yale astronomer Jeffrey Kenney looked at the way the cosmic wind is eroding the gas and dust at the leading edge of the galaxy. The wind, or ram pressure, is caused by the galaxy’s orbital motion through hot gas in the cluster. Kenney found a series of intricate dust formations on the disk’s edge, as cosmic wind began to work its way through the galaxy.
“On the leading side of the galaxy, all the gas and dust appears to be piled up in one long ridge, or dust front. But you see remarkable, fine scale structure in the dust front,” Kenney explained. “There are head-tail filaments protruding from the dust front. We think these are caused by dense gas clouds becoming separated from lower density gas.”
Cosmic wind can easily push low-density clouds of interstellar gas and dust, but not high-density clouds. As the wind blows, denser gas lumps start to separate from the surrounding lower density gas which gets blown downstream. But apparently, the high and low-density lumps are partially bound together, most likely by magnetic fields linking distant clouds of gas and dust. ...
HST and HI Imaging of Strong Ram Pressure Stripping in the Coma Spiral NGC 4921:
Dense Cloud Decoupling and Evidence for Magnetic Binding in the ISM - Jeffrey D. P. Kenney, Anne Abramson, Hector Bravo-Alfaro
- Astronomical Journal 150(2) 59 (2015 Aug) 10.1088/0004-6256/150/2/59
arXiv.org > astro-ph > arXiv:1506.04041 > 12 Jun 2015