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Caerlaverock Castle

Caerlaverock Castle is a moated triangular castle, first built in the 13th century. It is located 11 kilometres south of Dumfries in south-west Scotland, on the edge of the Caerlaverock National Nature Reserve.

  1. Danyale

    is absolute magnitude or apparent magnitude relative to the distance from Earth?

  2. Chris

    Why does the size of a star correlate with bolometric luminosity? why cant a star be relatively small but bolometrically bright, or large but bolometrically dim?

  3. Phileas Fogg
    Phileas Fogg

    Does anybody know how to "unaccount" for the atmosphere when measuring absolute magnitude?

  4. tiffany forshee
    tiffany forshee

    okay so what is the difference between absolute and apparent magnitude?

    1. Palustec

      Apparent Magnitude - is how bright something appears to you from were you are.
      Absolute Magnitude - is how bright something looks from a set distance of 10 parsecs (32.6 lightyears).

      A dim star will still be very bright if you are really close to it. Conversely, a really bright star can be seen from very far away.

  5. AB Atwater
    AB Atwater

    I am very interested in astronomy, but I suck at mathematic calculations (go figure...). I am taking a class currently, and a question posed is as follows:

    Polaris is a second-magnitude star. Phi Pegasi is about sixteen times fainter than Polaris. What is the approximate magnitude of Phi Pegasi?

    I have been given the choices of 18, -14, 3, -3, and 5. I do not know the calculation/equation that I need to use to reach an answer. I am not asking that you answer this for me, but I would like to know / to understand the appropriate equation. Please respond via e-mail, as soon as possible. Thank you!

    1. Palustec

      The answer is 5th magnitude (apparent).

      each magnitude is 2.512 brighter or fainter then the next increment. So a 1st magnitude star is 2.512 times brighter then a 2nd magnitude star. Therefore, 2.512 * 2.512 * 2.512 = 15.85 times brighter or fainter - notice that 15.85 is close to 16). So that means there are 3 magnitudes of difference between Polaris and Phi Pegasi - so 2 (mag of Polaris) + 3 (mag diff) = 5 th mag for Phi Pegasi.

  6. Jerry Abbott
    Jerry Abbott

    Does anybody know the equation relating all-spectrum flux with bolometric apparent magnitude?

    If we know that a certain star has a bolometric apparent magnitude of EXACTLY zero, then how many watts per meter squared do you get from it when you integrate over the entire spectrum?

  7. carolina

    omg this calculation is so difficult

  8. Su

    (m-M) = 5logd-5. Great but how do I get d = ?????
    I cannot see how to rearrange can you help
    Many thanks

    1. Palustec

      d = 10^(1 + (m-M)/5)

      10 raised to the power of 1 plus the quantity of apparent mag minus absolute mag divided by 5.

      a quick sanity check: if m = M then 10 raised to the 1st power is 10. which is 10 parsecs.

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