A state of stellar evolution beyond the main-sequence life of a star. A red giant core is degenerate ionized helium, surrounded by a shell of hydrogen fusion, that expands the outer atmosphere in response to higher core temperatures. The hydrogen fusing shell eats through the surrounding atmosphere and deposits helium onto the shrinking core. The ballooning atmosphere cools and glows red; hence red giant. The Sun will become a red giant the size of Earth's orbit in five to six billion years. Once the helium core reaches 100 million degrees, it explosively begins fusing helium. The birth of the active helium core is called the helium flash. The Sun as a red giant will fuse helium for about 2 billion years after the helium flash.
Radio Programs
Serpens
Piecing together a celestial snake
Saturday, May 12, 2012
Capella
A quick exit for a “heavy” star
Friday, April 27, 2012
Beta Pegasi
Taking a look into the future
Wednesday, November 30, 2011
Sagitta
Arrowing into the autumn season
Sunday, September 4, 2011
Early Summer
Flip-flopping the seasons
Tuesday, December 14, 2010
Vulpecula
A dead star and an almost-dead star
Saturday, August 7, 2010
Eltanin
In search of the dragon's head
Wednesday, June 23, 2010
Hercules
A fairly weak "strongman"
Monday, May 3, 2010
Gamma Hydra
A star that's close to retirement
Friday, April 9, 2010
Unicorn Stars
Impressive stars for the unicorn
Wednesday, February 24, 2010
Lynx
Padding after a faint celestial cat
Saturday, February 13, 2010
Tin
Heavy metal the slow way
Thursday, January 21, 2010
Keeping Watch
Keeping watch on a distant star
Thursday, August 20, 2009
Giants
Giant stars in the evening sky
Sunday, July 26, 2009
RS Ophiuchi
One star gives, another takes
Monday, June 1, 2009
Rasalhague
A preview of coming attractions
Sunday, May 31, 2009
Big Hand
A big hand for a snake charmer
Sunday, May 24, 2009
Resources
Constellation Guide:
Aries, the Ram
Aries, the ram, is a faint pattern marked by...
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