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Astronomers catch dwarf galaxy ramming into larger spiral galaxy

New find questions current theories about the evolution of the universe

According to an August 14 news release from NASA’s Marshall Space Flight Center in Huntsville, Alabama, analysis of images captured by the Chandra X-ray Observatory revealed a massive cloud of approximately six million-degree gas in a galaxy approximately 60 million light years from Earth.  NASA scientists believe that the hot gas cloud is the result of a collision between a dwarf galaxy and the much larger galaxy NGC 1232.  Though further analysis of this discovery is necessary, if it is in fact confirmed, this would be the first time that such a collision has been detected only in X-rays.  Scientists say that the discovery could have implications for understanding how other galaxies grow through similar collisions.

According to NASA scientists, the impact between the dwarf galaxy and the spiral galaxy created a massive shock wave that spawned hot gas with a temperature of approximately six million degrees. The Chandra X-ray images depicted the hot gas as having a comet-like form, triggered by the gesticulation of the dwarf galaxy.  Around the nose of the comet-shaped X-ray emission is an expanse that contains multiple bright stars and heightened X-ray emissions.  Scientists speculate that the shock wave may have triggered star formation, creating bright, gigantic stars.  If this speculation turns out to be true, then the X-ray emission would have been created by colossal solar winds, in addition to the remnants of supernovae explosions.

Because the X-ray image is limited to two-dimensions, scientists do not exactly know what the mass of the entire gas cloud is, as the hot gas may be focused in a thin pancake, or it could be dispersed over an enormous, spherical region.  In the case of the pancake shape, the mass is equivalent to forty thousand Suns.  However, if the gas cloud is uniformly spread out, the mass could be approximately three million times as massive as the Sun.

Scientists acknowledge an alternative explanation of the X-ray emission, which is that the hot gas cloud may have been created by supernovas and the resulting winds from massive stars, all of which are positioned on one edge of the galaxy.  However, the paucity of evidence of radio, infrared, or optical features suggests that this may not be possible.

The findings are described in a scholarly paper by Gordon Garmire of the Huntingdon Institute for X-ray Astronomy in Huntingdon, Pennsylvania, which appeared in the June 10 issue of The Astrophysical Journal.