Two spectacular tails of X-ray emission have been seen trailing behind a galaxy known as ESO 130-001 using the Chandra X-ray Observatory. Previously, the Abell 3627 cluster was largely unstudied. Although it is both nearby and bright, its apparent position near the plane of the Milky Way makes it difficult to observe because it is obscured by interstellar dust at optical wavelengths.
ESO 137-001 is plunging into the galaxy cluster causing its cooler gas to be stripped by the cluster’s much hotter gas. The brighter of the two tails has been seen before and extends for about 260,000 light years. The detection of the second, fainter tail, however, was a surprise to the scientists.
The X-ray tails were created when cool gas from ESO 137-001 (with a temperature of about ten degrees above absolute zero) was stripped by hot gas (about 100 million degrees) as it travels towards the center of the galaxy cluster. What astronomers observe with Chandra is essentially the evaporation of the cold gas, which glows at a temperature of about 10 million degrees. Evidence of gas with temperatures between 100 and 1,000 degrees Kelvin in the tail was also found with the Spitzer Space Telescope.
Phenomena like these in ESO 137-001 have a significant effect on how galaxies evolve. The stripping of gas is thought to have a significant effect on galaxy evolution, removing cold gas from the galaxy, shutting down the formation of new stars in the galaxy, and changing the appearance of inner spiral arms and bulges because of the effects of star formation.
The H-alpha data shows evidence for star formation in the tails — the first unambiguous evidence that star formation can occur when cold gas is stripped out of galaxies as they fall through clusters. The Chandra data also reveal an excess of luminous X-ray point sources around the X-ray tails. Some of them are considered to be young massive binary stars associated with nearby young star clusters, giving more evidence of star formation in the tails.