{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

rev.ex1.fall.10 - Cosmic Catastrophes 309N Fall 2010(47700...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Cosmic Catastrophes Wheeler 309N Fall 2010 September 3, 2010 ( 47700 ) Review for Test #1 BACKGROUND AND INTRODUCTION TO SUPERNOVAE Gravity – acts as if all the mass beneath were concentrated in the center. Gravity at surface depends on the mass and the radius of the object. Gravity is stronger inside massive, compact stars. Gravity gets weaker further away from any object. Stellar balancing act — dynamic equilibrium. A star spends most of its lifetime at a relatively constant size, temperature, luminosity, etc. while it fuses some fraction of its hydrogen into helium. During this time there is a balance between the forces inward and the forces outward. Forces inward — due to gravity, without the forces acting outwards the star would collapse. Forces outward — pressure Thermal pressure — For most of the lifetime of the star this is the dominant source of outward pressure. With this pressure a star can regulate its temperature. Regulated temperature – the nuclear burning is regulated on the main sequence. If too much energy is temporarily lost, the star contracts and heats, increasing nuclear input. If too much energy is temporarily gained, the star expands and cools, and nuclear input declines.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern