The Dramatic Lives of Stars
with images from "The Universe at your Fingertips 2.0" Astronomical Society of the Pacific
Death Adulthood
Old age
Childhood
Death leads to raw materials for new stars Main sequence
Birth of stars
Death of stars Main sequence
Birth of stars
Death of stars
Main sequence
Carina Nebula Orion Nebula Pleiades Young stars are called “Pre-main sequence” stars. They sit to the upper right of the main sequence in an HR diagram. Given the position of young stars in the HR diagram, which of the following is true? A 0.5 solar mass star mostly:
A. Grows as it ages B. Shrinks as it ages C. Heats up as it ages D. Cools as it ages Given the position of young stars in the HR diagram, which of the following is true? A 9 solar mass star mostly:
A. Grows as it ages B. Shrinks as it ages C. Heats up as it ages D. Cools as it ages Given the position of young stars in the HR diagram, which of the following is true? A star like the sun both:
A. Grows and heats up as it ages B. Grows and cools as it ages C. Shrinks and heats up as it ages D. Shrinks and cools as it ages The Main sequence Main Sequence Star: Sun Main Sequence Stars come in a range of masses, sizes and temperatures: The (northern hemisphere) winter night sky
Credit & Copyright: Jimmy Westlake (Colorado Mountain College) Some of the brightest main sequence stars in the winter night sky
Castor
Procyon Sirius
Credit & Copyright: Jimmy Westlake (Colorado Mountain College) Have a look at this artist’s depiction of the sizes and colors of main sequence stars.
Do you notice a relationship between color and size?
How would you plot these stars on an HR diagram?
Where does a star’s energy come from on the main sequence? Nuclear fusion fuels stars
Aldebaran: A red giant Which star is Aldebaran? Any guesses? Aldebaran: A red giant
Aldebaran Betelgeuse: A red supergiant Which star is Betelgeuse? Any guesses? Betelgeuse: A red supergiant Which star is Betelgeuse? Any guesses?
Betelgeuse Betelgeuse: A red supergiant
Only the second image EVER taken of the surface of a star Where is Aldebaran? Where is Betelgeuse? Red supergiants
Red giants Why do giant and supergiant stars become large and red?
NOT to scale. Red giant stars are MUCH larger Red giant Aldebaran and the sun to scale Why do giant and supergiant stars become large and red?
NOT to scale. Red supergiant stars are MUCH larger Betelgeuse and sun to scale What happens when stars are no longer able to fuse atoms together?
Ring Nebula Ring Nebula
White dwarf How would you describe the color and size of white dwarfs?
Supernova 1987A Where do you think an exploding supernova would be on an HR diagram? Where do you think an exploding supernova would be on an HR diagram? Crab Nebula: A supernova remnant Supernova 1987A The remnant of SN 1987A
http://spiff.rit.edu/classes/phys230/lectures/star_age/evol_hr.swf