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Red Giants

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.

Resources

Aries, the ram

Aries, the Ram October 4, 2011

Radio Programs

Menkent An over-represented class of stars June 1, 2017

The Solitary One A solitary light in a zone of darkness April 29, 2017

Moon and Aldebaran The Moon faces the bull March 31, 2017

Moon and Aldebaran A star with a “fuzzy” appearance February 5, 2017

Moon and Aldebaran Things get complicated for a star September 20, 2016

Bow and Arrow Plucking a bright celestial bow August 15, 2016

Moon and Aldebaran Big, fluffy, bright, and orange July 1, 2016

Arcturus Extra pounds cut billions of years June 12, 2016

Moon and Aldebaran Looking at the future of the Sun December 23, 2015

El Nath Sharing a bright star December 20, 2015

Rising Serpent Piecing together a celestial snake May 15, 2015

Bear’s Nose The shiny nose of the great bear May 9, 2015

Alphard A long but barren constellation March 22, 2015

Beta Cassiopeia Watching a star puff up February 27, 2015

Moon and Aldebaran The cool glow of a bright star February 24, 2015

Perseus Taking the measure of a monster January 24, 2015

Moon and Aldebaran The beginning of the end July 3, 2013

Crimson Star An aging but colorful star February 2, 2013

The Footstool A footstool for the hunter December 27, 2012

Menkar A constellation with a case of the big head November 17, 2012

Bear’s Nose The great bear’s shiny nose May 26, 2012

Serpens Piecing together a celestial snake May 11, 2012

Capella A quick exit for a “heavy” star April 26, 2012

Venus and Aldebaran The demise of a star and planet April 7, 2012

Featured Images

Diagram comparing sizes of Sun, Aldebaran

Giant Eye July 21, 2014