Astronomy Picture of the Day
Posted By admin On November 5, 2011 @ 9:09 pm In Photo Essays | Comments Disabled
[1]Image Credit & Copyright [2]: Adam Block [3], Mt. Lemmon SkyCenter [4], University of Arizona [5]
Explanation: Early in the 20th century, GK Persei [6] briefly became one of the brightest stars in planet Earth’s sky, an event known as Nova Persei 1901. Documented in this modern day composite [7] of two images from 2003 and 2011 the ejecta from the explosion, popularly called the Firework Nebula, continues to expand into space. These images are part of a time lapse video [8] tracking the nebula’s expansion over the last 17 years. About 1500 light-years away, the nebula is still just under a light-year in diameter. GK Per and similar cataclysmic variable stars [9] known as classical novae are understood to be binary systems consisting of a compact white dwarf star and swollen cool giant star [10] in a close orbit. The build up of mass transferred to the surface of the white dwarf from the giant star through an accretion disk eventually triggers a thermonuclear outburst, blasting the stellar material into space without destroying the white dwarf star. With a 2 day orbital period, the GK Per system [11] has produced much smaller outbursts in recent years [12].
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URL to article: http://www.berthoudrecorder.com/2011/11/05/astronomy-picture-of-the-day-85/
URLs in this post:
[1] Image: http://www.berthoudrecorder.com/wp-content/uploads/2011/11/gkper_block-cropped1.jpg
[2] Copyright: http://apod.nasa.gov/apod/lib/about_apod.html#srapply
[3] Adam Block: http://www.caelumobservatory.com/index.html
[4] Mt. Lemmon SkyCenter: http://skycenter.arizona.edu/
[5] University of Arizona: http://www.as.arizona.edu/
[6] 20th century, GK Persei: http://www.aavso.org/vsots_gkper
[7] this modern day composite: http://www.caelumobservatory.com/gallery/gkper.shtml
[8] time lapse video: http://vimeo.com/31120259
[9] cataclysmic variable stars: http://apod.nasa.gov/apod/ap091117.html
[10] white dwarf star and swollen cool giant star: http://apod.nasa.gov/apod/ap060726.html
[11] GK Per system: http://apod.nasa.gov/apod/ap980704.html
[12] in recent years: http://www.aavso.org/node/1555/3095
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