If I Die 2Night
22nd August 2010, 03:11 PM
2010 August 22
http://antwrp.gsfc.nasa.gov/apod/image/1008/hoag_hst.jpg (http://antwrp.gsfc.nasa.gov/apod/image/1008/hoag_hst_big.jpg)
Hoag's Object: A Strange Ring Galaxy
Credit: R. Lucas (http://heritage.stsci.edu/2002/21/bio/bio_01.html) (STScI (http://www.stsci.edu/)/AURA (http://www.aura-astronomy.org/)), Hubble Heritage Team (http://heritage.stsci.edu/commonpages/infoindex/ourproject/moreproject.html), NASA (http://www.nasa.gov/) Explanation: Is this one galaxy or two? This question came to light in 1950 when astronomer Art Hoag (http://en.wikipedia.org/wiki/Arthur_Allen_Hoag) chanced upon this unusual extragalactic object (http://bb.nightskylive.net/asterisk/viewtopic.php?f=24&t=18005). On the outside is a ring (http://antwrp.gsfc.nasa.gov/apod/ap051022.html) dominated by bright blue stars, while near the center lies a ball of much redder stars that are likely much older. Between the two is a gap (http://antwrp.gsfc.nasa.gov/apod/ap040702.html) that appears almost completely dark. How Hoag's Object (http://adsabs.harvard.edu/abs/1990ApJ...348..448W) formed remains unknown, although similar objects have now been identified and collectively labeled (http://mergers.galaxyzoo.org/) as a form of ring galaxy (http://antwrp.gsfc.nasa.gov/apod/ap010612.html). Genesis hypotheses include a galaxy collision (http://nedwww.ipac.caltech.edu/level5/Struck/frames.html) billions of years ago and the gravitational affect of a central bar (http://antwrp.gsfc.nasa.gov/apod/ap080622.html) that has since vanished (http://adsabs.harvard.edu/doi/10.1007/s10569-010-9289-z). The above (http://heritage.stsci.edu/2002/21/caption.html) photo (http://hubblesite.org/gallery/album/galaxy/pr2002021a/) taken by the Hubble Space Telescope (http://antwrp.gsfc.nasa.gov/apod/ap010806.html) in July 2001 reveals unprecedented details of Hoag's Object and may yield a better understanding (http://nedwww.ipac.caltech.edu/level5/Rings/Rings17_2.html). Hoag's Object spans about 100,000 light years (http://chandra.harvard.edu/photo/cosmic_distance.html) and lies about 600 million light years (http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html) away toward the constellation (http://www.astro.wisc.edu/%7Edolan/constellations/extra/constellations.html) of the Snake (Serpens (http://en.wikipedia.org/wiki/Serpens_%28constellation%29)). Coincidentally, visible in the gap (at about one o'clock) is yet another ring galaxy (http://antwrp.gsfc.nasa.gov/apod/ap040426.html) that likely lies far in the distance (http://antwrp.gsfc.nasa.gov/apod/ap020901.html).
Tomorrow's picture: unusual shadows
http://antwrp.gsfc.nasa.gov/apod/image/1008/hoag_hst.jpg (http://antwrp.gsfc.nasa.gov/apod/image/1008/hoag_hst_big.jpg)
Hoag's Object: A Strange Ring Galaxy
Credit: R. Lucas (http://heritage.stsci.edu/2002/21/bio/bio_01.html) (STScI (http://www.stsci.edu/)/AURA (http://www.aura-astronomy.org/)), Hubble Heritage Team (http://heritage.stsci.edu/commonpages/infoindex/ourproject/moreproject.html), NASA (http://www.nasa.gov/) Explanation: Is this one galaxy or two? This question came to light in 1950 when astronomer Art Hoag (http://en.wikipedia.org/wiki/Arthur_Allen_Hoag) chanced upon this unusual extragalactic object (http://bb.nightskylive.net/asterisk/viewtopic.php?f=24&t=18005). On the outside is a ring (http://antwrp.gsfc.nasa.gov/apod/ap051022.html) dominated by bright blue stars, while near the center lies a ball of much redder stars that are likely much older. Between the two is a gap (http://antwrp.gsfc.nasa.gov/apod/ap040702.html) that appears almost completely dark. How Hoag's Object (http://adsabs.harvard.edu/abs/1990ApJ...348..448W) formed remains unknown, although similar objects have now been identified and collectively labeled (http://mergers.galaxyzoo.org/) as a form of ring galaxy (http://antwrp.gsfc.nasa.gov/apod/ap010612.html). Genesis hypotheses include a galaxy collision (http://nedwww.ipac.caltech.edu/level5/Struck/frames.html) billions of years ago and the gravitational affect of a central bar (http://antwrp.gsfc.nasa.gov/apod/ap080622.html) that has since vanished (http://adsabs.harvard.edu/doi/10.1007/s10569-010-9289-z). The above (http://heritage.stsci.edu/2002/21/caption.html) photo (http://hubblesite.org/gallery/album/galaxy/pr2002021a/) taken by the Hubble Space Telescope (http://antwrp.gsfc.nasa.gov/apod/ap010806.html) in July 2001 reveals unprecedented details of Hoag's Object and may yield a better understanding (http://nedwww.ipac.caltech.edu/level5/Rings/Rings17_2.html). Hoag's Object spans about 100,000 light years (http://chandra.harvard.edu/photo/cosmic_distance.html) and lies about 600 million light years (http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html) away toward the constellation (http://www.astro.wisc.edu/%7Edolan/constellations/extra/constellations.html) of the Snake (Serpens (http://en.wikipedia.org/wiki/Serpens_%28constellation%29)). Coincidentally, visible in the gap (at about one o'clock) is yet another ring galaxy (http://antwrp.gsfc.nasa.gov/apod/ap040426.html) that likely lies far in the distance (http://antwrp.gsfc.nasa.gov/apod/ap020901.html).
Tomorrow's picture: unusual shadows