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Astronomy Picture of the Day
Posted By Editor On April 7, 2011 @ 9:38 pm In Photo Essays | Comments Disabled
NGC 2438 is a planetary nebula, the gaseous shroud cast off by a dying sunlike star billions of years old whose central reservoir of hydrogen fuel has been exhausted.
Explanation: NGC 2438  is a planetary nebula , the gaseous shroud cast off by a dying sunlike star billions of years old whose central reservoir of hydrogen fuel has been exhausted. About 3,000 light-years distant it lies within the boundaries of the nautical constellation Puppis . Remarkably, NGC 2438 also seems to lie on the outskirts of bright, relatively young open star cluster M46 . But this planetary nebula’s central star  is not only much older than the stars of M46, it moves through space at a different speed than the cluster stars. Distance estimates also place NGC 2438 closer than M46  and so the nebula appears in the foreground, only by chance along the line-of-sight to the young star cluster. This deep image of NGC 2438  highlights a halo of glowing atomic gas over 4.5 light-years across, extending beyond the nebula’s brighter inner ring. Similar haloes have been found in deep images of other planetary nebulae , produced during the earlier active phases of their aging central stars.
Visit the NASA/JPL website to view more Astronomy Pictures of the Day 
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URL to article: http://www.berthoudrecorder.com/2011/04/07/astronomy-picture-of-the-day-52/
URLs in this post:
 Image: http://www.berthoudrecorder.com/wp-content/uploads/2011/04/NGC2438_IAC80_DLopez.jpg
 Copyright: http://apod.nasa.gov/apod/lib/about_apod.html#srapply
 Daniel López: mailto: dlp at iac dot es
 IAC: http://www.iac.es/
 NGC 2438: http://seds.org/messier/xtra/ngc/n2438.html
 planetary nebula: http://apod.nasa.gov/apod/ap110218.html
 constellation Puppis: http://www.hawastsoc.org/deepsky/pup/index.html
 young open star cluster M46: http://apod.nasa.gov/apod/ap090326.html
 central star: http://www.noao.edu/outreach/aop/observers/n2438.html
 closer than M46: http://apod.nasa.gov/apod/ap101202.html
 This deep image of NGC 2438: http://www.iac.es/telescopes/IAM/2011/72_abr11_ngc2438.jpg.html
 planetary nebulae: http://www.ing.iac.es/~rcorradi/HALOES/
 Astronomy Pictures of the Day: http://antwrp.gsfc.nasa.gov/apod/
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