NGC 7252
Published on Dec 27, 2007 at 5:51 pm.
2 Comments.
Filed under galaxies.
NGC 7252 is located in the southern part of Aquarius, in the southern sky at Sunset here in the northern hemisphere this time of year. In a small telescope, it looks like just a blob, and it was long classified as an elliptical galaxy. Larger telescopes showed that NGC 7252 has large loops of gas and stars around it, making it quite peculiar. Thus, it is also Arp 226 (the 226th entry in Arp’s list of peculiar galaxies). But, one of the things that is really interesting to me about this galaxy is that NGC 7252 is one of a handful of galaxies with names. It is called the “Atoms for Peace Galaxy.” I have tried to find out who first named it thus, but I haven’t had much luck. If anyone knows, be sure to leave a comment telling the rest of us! However, I am pretty sure that the name dates back to the mid 1950s. In December of 1953, President Eisenhower made a speech dubbed the “Atoms for Peace” speech, in which he promoted the peaceful uses of nuclear energy. The “Atoms for Peace” concept was honored by the United States post 
office with a commemorative stamp in July, 1955. So, it would seem to make sense that the galaxy received its nickname at about that same time. Reportedly, the name refers to the fact that the loops of gas around the galaxy somewhat resemble the classic picture of electrons moving around atoms (Note: Atoms do not really look like that!). The name for this galaxy probably seemed like a modern and impressive name at the time, but today it just sounds sort of weird.
NGC 7252 is nearly 220 million lightyears away from us. Is appears dim in small telescopes, magnitude 12.7. It looks like a very small fuzzy spot in the sky through small telescopes, too, appearing only 1.9×1.6 arcminutes. (Data from the NASA Extragalactic Database).
For quite some time astronomers have knows that the streams of material around NGC 7252 result for a galaxy collision. In fact, this peculiar galaxy is most likely the result of two similar sized galaxies coming together slow enough to merge into one structure. This may be the future of the Milky Way and the Andromeda galaxy when they collide and merge. Astronomers believe that the collision leading to the merger of NGC 7252 may have been about one billion years ago. A closeup image of the core of the galaxy shows a spiral structure that mimics the shape of a classic spiral galaxy, only in miniature. The spiral feature may have been caused by the collision itself. Much of the galaxy’s interstellar medium is being ejected from the collision, but some of the material was compressed in the collision itself, leading to a burst of star formation. Hundreds of extra luminous star clusters containing stars only tens to hundreds of millions of years old have been identified. These unusual star clusters appear to be the progenitors of globular clusters. That is an interesting finding, since we seldom seem globular clusters forming. That globular clusters can be formed in a galaxy collision event is every exciting, since this would tend to explain how elliptical galaxies, most of which are believed to have formed in galaxy collisions, have far more globular clusters than could be explained by simply adding the globular clusters of colliding spiral galaxies.
So, if you have clear dark skies, and you are good at finding things with your telescope, you may wish to look at the Atoms for Peace Galaxy.
-Astroprof
Galaxy images courtesy of NASA, HST
Ed Davies on December 28, 2007 at 4:01 am: 1
“In a small telescope, it looks like just a blog,…”. Yes, but with which stylesheet?
Sorry, but as typos go, that’s rather cute.
Astroprof on December 28, 2007 at 11:51 am: 2
Thanks, Ed. I fixed the typo, since not everyone would read the comment!