Colliding galaxies make love, not war17 October 2006

This Hubble image of the Antennae galaxies is thesharpest yet of this merging pair of galaxies. As the twogalaxies smash together, billions of stars are born,mostly in groups and clusters of stars. The brightest andmost compact of these are called super star clusters.Credit: Credit: NASA, ESA, and B. Whitmore (SpaceTelescope Science Institute). Acknowledgement: JamesLong (ESA/Hubble).

A new Hubble image of the Antennae galaxies isthe sharpest yet of this merging pair of galaxies. Asthe two galaxies smash together, billions of starsare born, mostly in groups and clusters of stars.The brightest and most compact of these arecalled super star clusters.

The Universe is an all-action arena for some of thelargest, most slowly evolving dramas known tomankind. A new picture taken by the AdvancedCamera for Surveys (ACS), onboard theNASA/ESA Hubble Space Telescope, shows the"best ever" view of the Antennae galaxies -seemingly a violent clash between a pair of onceisolated galaxies, but in reality a fertile marriage.As the two galaxies interact, billions of stars areborn, mostly in groups and clusters of stars. The

brightest and most compact of these are calledsuper star clusters.

The two spiral galaxies started to fuse togetherabout 500 million years ago making the Antennagalaxies the nearest and youngest example of apair of colliding galaxies. Nearly half of the faintobjects in the Antennae are young clusterscontaining tens of thousands of stars. The orangeblobs to the left and right of image centre are thetwo cores of the original galaxies and consistmainly of old stars criss-crossed by filaments ofdark brown dust. The two galaxies are dotted withbrilliant blue star-forming regions surrounded bypink hydrogen gas.

The image allows astronomers to better distinguishbetween the stars and super star clusters createdin the collision of two spiral galaxies. Theobservations show that only about 10% of thenewly formed super star clusters in the Antennaewill live to see their ten millionth birthday. The vastmajority of the super star clusters formed duringthis interaction will disperse, with the individualstars becoming part of the smooth background ofthe galaxy. It is however believed that about ahundred of the most massive clusters will survive toform regular globular clusters, similar to theglobular clusters found in our own Milky Waygalaxy.

The Antennae galaxies take their name from thelong antenna-like "arms" extending far out from thenuclei of the two galaxies, best seen by ground-based telescopes. These "tidal tails" were formedduring the initial encounter of the galaxies some500 million years ago. The give us a preview ofwhat may happen when our Milky Way galaxy likelycollides with the neighbouring Andromeda Galaxyabout 6 billion years from now.

Source: ESA/Hubble Information Centre

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APA citation: Colliding galaxies make love, not war (2006, October 17) retrieved 15 May 2015 from http://phys.org/news/2006-10-colliding-galaxies-war.html

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