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Abell 3627: Two Tails to Tell

  • Two spectacular tails of X-ray emission have been found behind the galaxy known as ESO 130-001.

  • ESO 137-001 is plunging into a galaxy cluster causing its cooler gas to be stripped by the cluster's much hotter gas.

  • Phenomena like these in ESO 137-001 have a significant effect on how galaxies evolve.

Two spectacular tails of X-ray emission have been seen using the Chandra X-ray Observatory trailing behind a galaxy. A composite image of the galaxy cluster Abell 3627 shows X-rays from Chandra in blue, optical emission in yellow and emission from hydrogen light -- known to astronomers as "H-alpha" -- in red. The optical and H-alpha data were obtained with the Southern Astrophysical Research (SOAR) Telescope in Chile.

At the front of the tail is the galaxy ESO 137-001. 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 Abell 3627. 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.

Galaxy clusters are collections of hundreds or even thousands of galaxies held together by gravity that are enveloped in hot gas. The two-pronged tail in this system may have formed because gas has been stripped from the two major spiral arms in ESO 137-001. 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. The implication is that a large portion of stars between cluster galaxies can be formed in situ.

The X-ray data also reveal that there is little change in temperature of the hot gas in the tails, and also little change in width of the tails with distance from ESO 137-001. Both of these features present challenges to scientists doing simulations of the galaxy tails.

Fast Facts for Abell 3627:
Credit  X-ray: NASA/CXC/UVa/M. Sun, et al; H-alpha/Optical: SOAR (UVa/NOAO/UNC/CNPq-Brazil)/M.Sun et al.
Release Date  January 21, 2010
Scale  Image is 5 arcmin across.
Category  Groups & Clusters of Galaxies
Coordinates (J2000)  RA 16h 13m 25.59s | Dec -60° 45´ 43.10"
Constellation  Norma
Observation Date  6/12/2008
Observation Time  39 hours
Obs. ID  9518
Instrument  ACIS
References Sun, M., et al, 2010, ApJ 708 946
Color Code  X-ray (Blue); Optical (Yellow); H-alpha (Red)
Distance Estimate  About About 230 million light years
distance arrow
Visitor Comments (5)

If absolute zero is the lowest temperature, what is the highest temperature?

Posted by jim on Thursday, 11.20.14 @ 16:13pm

Thank you Robert for the note.


Posted by Chandra on Wednesday, 06.2.10 @ 13:35pm

Two spectacular tails of X-ray emission have been seen trailing behind a galaxy using the Chandra X-ray Observatory. If this galaxy is so far away just how can it be using the Chandra X-ray Observatory.
Real English is so much better when used precisely.

Posted by Robert H Mercer on Sunday, 05.30.10 @ 02:05am

I like this cluster of stars because of the color and the shape of it.

Posted by janeth on Monday, 02.22.10 @ 16:49pm

That is a most interesting discovery and beautiful photo of a momentous event. Astronomy never ceases to amaze me.

Marvin L S

Posted by Marvin L.S. on Sunday, 01.24.10 @ 18:10pm

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