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8/08/2015

NGC 7252 Atom for Peace Merging Galaxies ARP 226


    


From: "NGC 7252" by ESO - http://www.eso.org/public/images/eso1044a/. Licensed under CC BY 4.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:NGC_7252.jpg#/media/File:NGC_7252.jpg


   This galaxy is known in the amateur community, yet I cannot find that many images of it and I find no sketch of it. At blue magnitude 12.6 (12.7 in some catalogs) and a visual magnitude of 11.7 and a surface brightness of 12.8 it should be able to be seen and sketched. How much is visible I do not know since I have never captured this galaxy.  I would be greatly amiss though if I did not mention Jimi Lowrey's observations of this object over at the Deep Sky Forum at this LINK.  He has observed this peculiar galaxy "many times over the years" and his post there breaks down some of the more challenging visual parts to go after. I encourage you to look at that post. Jimi mentions in article on this object (it is a very well studied professional object) and which is at the top of this list of articles if your so incline to study/read up on the professional papers of an object you like to observe (I do) LINK (arxiv search results). It gets its name from a speech that then President Eisenhower gave in December of 1953 called the "Atoms for Peace Speech."  There President Eisenhower called for peaceful uses of nuclear power and this galaxy, in images looks like an electron going around the nucleus of an atom so it was named after that speech.

     Jimi points out in his article and Wikipedia does as well that in a paper published about  NGC 7252 "In August 2013, F. Schweizer and others published a paper in the Astrophysical Journal titled "The [O III] Nebula of the Merger Remnant NGC 7252: A Likely Faint Ionization Echo."  This reports the finding of a Voorwerpje on the outskirts of the well-studied NGC 7252." LINK to article. I and see the Wikipedia article  LINK.  If you go to Jimi's post he has a finder chart there for the Voorwerpje in NGC 7252 and a massive star cluster, W-3 which is over a hundred times more massive than our globular clusters and may be the remnant of a galaxy core from an earlier merger.

     This object gets even cooler I believe. In 1993 using the Hubble Space Telescope, this team of astronomers,  Dr. Bradley Whitmore of the Space Telescope Science Institute (STScI) in Baltimore, Maryland and Dr. Francois Schweizer of the Carnegie Institution of Washington. Co-investigators in the Hubble findings are Drs. Claus Leitherer, Kirk Borne, and Carmelle Robert of STScI. Dr. Schweizer's co-worker in the Hale Telescope research is Dr. Patrick Seitzer of the University of Michigan at Ann Arbor. discovered several key things about this galaxy.

     Here are their findings summed up from the NASA article at this LINK by  Dr. Bradley Whitmore:

     "I knew we had a major result within 10 seconds of looking at the Hubble picture," said Whitmore. "This may provide a clue to how all globular clusters formed." He added, "The Hubble observation also shows how tiny, disk-like structures may have formed near the centers of many other galaxies."
The striking image shows a spiral pattern at the galaxy's core, which is surrounded by bright star clusters.
The Hubble observations succeeded in resolving the globular clusters, that is, measuring their apparent sizes on the sky despite the vast distance of NGC 7252. The galaxy is 300 million light- years from the Earth, and located in the constellation Aquarius.
The clusters are typically about 0.04 arc seconds in diameter, which corresponds to the apparent size of a dime, seen from a distance of 60 miles. This means that the clusters are each about 60 light-years in diameter, the same size as the globular star clusters of our own Milky Way."

     Furthermore, though we won't see this visually, it is a cool feature of this galaxy (from the merger 1 billion years ago) that  "the pinwheel structure found in the Hubble observations of the central disk of NGC 7252 consists of a system of interstellar gas and stars, orbiting the bright nucleus of NGC 7252. The gas and stars in the disk look like the swirling pattern formed by cream just mixed into a cup of coffee."  Here is an image of that pinwheel shape (you'll see it in the Wikipeida article but the visual view in that article is down lower):



   

     Perhaps one of the main reasons NGC 7252 is significant and this paper was back twenty-two years ago, is the fact that it shows that merging spiral galaxies can form into ellipticals and form new and thus have more globular clusters in them.  It reinforces the notion of where we get elliptical galaxies from. From a visual standpoint Dr. Whitmore states "If the globular clusters in the Milky Way were as bright as the newly found clusters in NGC 7252, many of them would be brighter than the stars in the Big Dipper, and readily visible to the naked eye." Now that would be cool!

     So with this object my goals would be to observe the tidal tails here, evidence of the merger of two galaxies.  Jimi states they are hard to see and I am sure they are, but I'll give it a go in the 17.5" and the 24" just to see if I can.  The next item or object would be a little Voorwerpje and the super cluster of stars called M-3.  Here is the Hubble image from above labeled and you can go to Jimi's post at Deep Sky Forum (above link) to see his rendering.



     In truth though, unlike that fine Hubble image, I expect the galaxy at magnification to look rather like the first image, or perhaps, even more realistically the second image.





     So how do you get to this object? Rather easy.  I have included a basic finder chart here and it is in the constellation of Aquarius.  Good luck and I'll be reporting my findings and I hope you share yours. Remember to enjoy the wonders of the sky!





     Edit:  I left off two links to sites that pertain to items in this galaxy that I think some may enjoy. The first is to Galaxy Zoo's forum where they discuss the Voorwerpje  at this LINK.  Great images there of the Voorwerpie.  This is a direct LINK to a pdf/power point done in NGC 7252 by Dr.  F. Schweizer and I recommend it if your into the scientific explanations behind objects you observe. Wonderful object and it will be a blast now that I have studied it to observe it, see what I can observe, document it via sketching and share. 


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