Lecture 15: The Main Sequence

What happens to a low-mass star (less than 4 solar masses) when it runs out of core Hydrogen and must leave the Main Sequence. This lecture describes the changes inside a low-mass star after Hydrogen exhaustion through the Red Giant, Horizontal Branch, Asymtotic Giant, and Planet ...  Show more

What happens when a high-mass (more than 4 solar masses) Main Sequence stars runs out of Hydrogen in its core. At first the internal evolution looks like that of a low-mass star, but now we get first a Red Supergiant then a sucession of blue and red supergiant phases as different ...  Show more

A new podcast, Astronomy 141, Life in the Universe, is available for those interested in continuing an exploration of topics in modern astronomy. 

What is Astronomy? What is Science? What is the course all about? Brief introductory remarks after going over course mechanics on the first day of Astronomy 161 for Autumn Quarter 2007. Recorded 2007 Sep 19 in 1000 McPherson Lab on the Columbus campus of The Ohio State University ...  Show more

Are we alone in the Universe? This lecture explores the question of how we might go about finding life on planets around other stars. Rather than talking about speculative ideas, like the Drake Equation or SETI, I am instead taking the approach of posing it as a problem of what t ...  Show more

Get ready to explore a 10 billion year old mystery! A closely bound duo of energetic quasars, the hallmark of a pair of merging galaxies, have been discovered when the Universe was only 3 billion years old. What secrets do these quasars hold and why have they lasted so long? Join ...  Show more