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Homework Help: Astronomy Help Please!

  1. Nov 19, 2006 #1
    Astronomy Help Please! :)

    I am having a problem figuring out this question. On all my other work the questions have been different. Could anyone help me with this Astronomy problem and show me how to work it out? Thank you! Anything would be greatly appreciated.

    What is the absolute magnitude of the sun--note apparent is -26 and its distance is 1 AU or 4.85 x 10^-6 parsec?

    Thanks so much!
  2. jcsd
  3. Nov 19, 2006 #2


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    You need to show some work before we can help you. Also, please only post in one forum at a time.
  4. Nov 19, 2006 #3
    Okay! Not a problem....I just didn't want to get confused with the stuff I have already done and then information given to me. What I have so far is this:

    M= m + 5 - (5 log D)

    M= (-26 + 5) - ( 5 log D)
    M= (-21) - (5 log D)

    ***My question is how to figure it out after this. I know it states D= 1 AU or 4.85 x 10^ -6, but I'm not sure what to put there to get the right answer.
  5. Nov 20, 2006 #4
    Am I on the right track???
  6. Nov 20, 2006 #5
    Yep. :smile:
    Distance is in parsecs.
  7. Nov 21, 2006 #6


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    Instead, try M=-5log(D/10pc)+m
    Make sure you're using a base 10 log on your calculator.

    Look up the answer in Wikipedia to double check yourself.
  8. Aug 29, 2007 #7

    does anyone knokw how to figure out-----

    what would the length of the synodic month if the moon's sidereal orbital period were (a) one week (7solar days) ; (b) 1 sidereal year.
  9. Nov 16, 2009 #8
    Re: Astronomy Help Please! :)

    can someone help me with the followng 2 questions, i am so confuzed. also tell me how you got the answer

    1. the minimum mass of a star is 0.08 solar mass or 80 jupiter masses. If the fuel that powered stars was helium instead of hydrogen would the minimum mass of stars be more, les or still be 0.08 sollar mass? (hint: think of the number of protons in nuclei)

    2. the sun emits as much energy as 3.9 *10^24 100- Watts light-bulbs (that’s a whole lot of light bulbs!) every second. We call that number its luminosity. Give that the radius of the sun is constant in time, how much energy is produced in the Sun every second? Is it more than, less than or equal to its luminosity? Justify your answer ( no calculations necessary)
  10. Nov 16, 2009 #9


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    Re: Astronomy Help Please! :)

    Please re-post this as a new thread - it's confusing when people tack a new question onto a years old question on a different topic .
    Also you have to make some attempt at an answer
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