Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Star Density Should be a piece of cake

  1. Jan 25, 2007 #1
    I am in Astr. 1020, and in my introductory Astronomy class I had last semester, we didnt learn anything. It was a "here's the study guide (aka the answers to the test)" kind of class so I didnt really learn that much.

    Now, my Astr. 1020 teacher is rather difficult due to what I didnt learn last semester...

    So on to the problem. For homework we have to find the density of Stars. It should be hard, mass (g) divided by volume (of a sphere, cm^3), I understand that much.

    In the problems, we are given everything relative to the sun (I hope I'm stating that correctly). So, the data we have for the sun is 1.0m(sun) and 1.0R(sun). How am I supposed to do this and get g/cm^3?

    I'm thinking, for example, Sirius (which is 2.0m(sun) and 2.0R(sun)) and multiply that by the mass and the radius of the sun, respectively. Is that right?

    Thanks for the help, guys! :blushing:
  2. jcsd
  3. Jan 26, 2007 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You are correct. If you want them in normal SI units then all you have to do is multiply their relative values by the suns actual values in SI units.
  4. Jan 27, 2007 #3


    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    You must factor the cubic volume and mass to derive the correct density.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Star Density Should be a piece of cake