ASOW 2012/04/22: In Fire and In Ice: The Death of Stars

[owlice]

In Fire and In Ice: The Death of Stars
Presenter: Dr. Rob Knop
Professor of Physics, Quest University, Canada

Stars live for millions or billions of years, but they don't live forever. When a star reaches the end of its lifetime, spectacular fireworks can result. In this popular talk for the interested layman, Dr. Knop outlines what it is that keeps a star together during its lifetime, and what happens to stars of various different sizes when that process finally breaks down. He talks about the ejection of planetary nebulae, the cooling of white dwarfs, and the most spectacular of stellar events, supernovae.
First presented in Second Life in May, 2008.

Dr. Knop will answer a selection of questions posted by May 6, 2012.



Audio (MP3, 58Mb)

A PDF of the slides can also be downloaded here (PDF, <1Mb)

Files also available here: http://www.mica-vw.org/wiki/index.php/Death_of_Stars

[emc]

Thank you Owlice!

Such a beautiful Robert Frost poem… I enjoyed the seminar! Funny, artistic and scientific!

[owlice]

Thanks, Ed!

[Guest]

Very nice - enjoyed it!

[geckzilla]

Pat (my fiancee) was wondering what kind of stars can collapse into black holes. Is it always neutron stars?

[rstevenson]

Pat (my fiancee) was wondering what kind of stars can collapse into black holes. Is it always neutron stars?

Most stars (I'm not sure about red dwarves) collapse to one degree or another at the end of their lives, when they run out of fuel and the pressure of radiation from their hot interiors is no longer sufficient to hold up their outer layers. When they collapse they will become some form of compact star, which could be a white dwarf, a neutron star or a black hole. Only the most massive stars -- those that were about 20 solar masses or greater before collapse -- will form a black hole.

Rob

[Chris Peterson]

Pat (my fiancee) was wondering what kind of stars can collapse into black holes. Is it always neutron stars?

Neutron stars are an alternative endpoint in stellar evolution to black holes. Black holes form when the stellar mass is about ten solar masses or more; neutron stars when it is only a couple of solar masses. The only way a neutron star can become a black hole is if it's in a binary system with another star of high mass, and manages to suck up enough material to further collapse. That probably happens, but is likely to be rare.