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Western Slope Skies: Star Formation

Black Canyon Astronomical Society logo

Our closest star, the Sun, is a middle-aged star.  This is good for us, but what exactly does ‘middle-aged star’ mean? 

Throughout their lives, stars are in a battle between gravity trying to collapse the star and pressure of the internal nuclear reaction trying to expand the star.

Make a note… It may take time, but gravity always wins!! 

Star formation begins with a massive cloud of dust and gasses.  The large majority of the cloud is hydrogen. 

External mechanisms will begin to compress the gas.  With continued compression, the cloud will become sufficiently dense that its own gravity will collapse the cloud further.  This raises the pressure and temperature to the point where a thermonuclear reaction begins and a star is born.  The hydrogen fuses to form helium and energy.

The eventual fate of a star depends primarily on its initial mass.  Large mass stars burn their hydrogen fast and have short lives. 

Lower mass stars like our Sun last for billions of years.  Our Sun is 4 to 5 billion years old and will last another 4 to 5 billion years.  During much of that time, the Sun’s output will be fairly constant.  THAT’S why a middle-aged Sun is good news for us!

When the hydrogen at the core is depleted, the Sun begins fusing helium and expands to a red giant.  When all the fuel is exhausted, gravity steps in, resulting in the collapse of the Sun to form a white dwarf.

Massive stars often end in an explosion called a supernova.  There are several types of supernovae.  One type marks the death of a massive star.

When a supernova explodes, you might think that gravity lost.  In fact, a supernova only extends the inevitable.  The material expelled from an exploding supernova will eventually collapse and become part of future stars and even planets.  Everything on Earth was once part of stars somewhere, even you and me.  Carl Sagan said it best “We are made of starstuff.”

Western Slope Skies is produced by members of the Black Canyon Astronomical Society.  This episode was written & recorded by Bryan Cashion.

A native Texan, Jeff was bitten by the Colorado "bug" after graduating from UT-Austin. He arrived in Paonia on the October full moon of 1978, and has been involved with KVNF since its earliest days. His first KVNF show was "Sunday Night Live," which featured live musicians performing in the original Garvin Mesa garage/studio.