Ring Nebula Classic Example of Star Death

No human has ever seen the complete life cycle of a star.  Thankfully the night sky offers a laboratory for studying stars at each stage of their evolution.  One of the best examples of star death is almost directly overhead on late summer nights.  

The Ring Nebula (M57) in Lyra the Harp is the remains of a star that in its prime was probably similar in mass to our own sun.   As a mid-sized star begins to run out of hydrogen, it expands and cools, forming a red giant star.  Because the star doesn't increase in mass its gravity remains the same and the outer layers are puffed off out into space.  This isn't the spectacular explosion of a super nova; but rather more like the expanding of a soap bubble.

The core of the star shrinks but continues to pour out energy of a variety of wavelengths.  This energy hits the expanding ring and causes it to glow, much like a fluorescent light. Gradually as the star loses energy the ring will cease to glow.

The Ring Nebula, and other nebulae like it, are known as planetary nebula because it was originally thought they were planet forming regions. 

M57, the Ring Nebula is located between the stars gamma lyre (Sulafat) and beta lyre (Sheliak) These are the two bright stars in Lyra opposite from Vega (alpha lyre).

The constellation Lyra and the ring nebula are nearly overhead for most mid-latitude locations throughout the rest of August and September.

M57 in Lyra created by the author using Stellarium

Close up of M57 using Stellarium