What’s Happening at Betelgeuse?

Astronomers are puzzled by the dimming of one of the brightest stars in the sky, Betelgeuse in Orion.

Supernova Dating and Classification Is Not Simple

Bang! goes a star. Watch how fast its contents move, and you know the date, right? Watch its light curve, and you know the type, right?

Observations Upset Models of Stellar Evolution

Stellar evolution models go back decades. Ever since the Hertzsprung-Russell diagram came out in 1910 (graphing temperature against luminosity), showing most stars fell on a line called the “main sequence”, astrophysicists have sought to understand the life cycle of stars from birth to death. In general, the story goes, collapsing clouds of gas and dust produce main-sequence stars that burn nuclear fuel till they run out. Depending on their masses, they end up as supernovae, red giants or slowly-cooling cinders. While red dwarfs cool down slowly into the darkness, supernovae and red giants eject mass outward into space . Two new planets found close to a red giant are among new headaches for theorists.
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