1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Planet transit to derive system parameters

  1. Oct 4, 2011 #1

    RHK

    User Avatar

    1. The problem statement, all variables and given/known data

    Measuring the flux of a star as a function of the time, the flux exhibit a decrease of 1.65% for 2h 56m, periodically every 57.22 days. Such decrease is ascribed to a planet transit.
    The continuous spectrum of the star is like a black body with T= 9500 K, and its bolometric luminosity is 22 times the bolometric luminosity of the Sun (that has a black body spectrum with T=5600K).
    Assuming that the planet transit is projected on the star equator, and that the planet is on a circular orbit, calculate:
    (i) The planet diameter;

    (ii) The orbit planet radius;

    (iii) The star mass.

    2. Relevant equations

    [itex]R_{sun} = 6.69*10^8 m[/itex]
    [itex]L_{bol}=4\pi R_s^2 \sigma T^4 [/itex]

    3. The attempt at a solution

    For the first point i can calculate the Sun bolometric luminosity with the same Stefan-Boltzmann law:
    [itex]L_{sun}=4\pi R_{sun}^2 \sigma T_{sun}^4 [/itex]

    and then calculate the bolometric luminosity of the star, that is 22*Lsun.
    This allow to obtain the stellar radius Rs by using the S-B law.
    Thus, the luminosity difference in the star is [itex]\Delta L= 4\pi(R_s^2 - R_{sun}^2) \sigma T_s^4 [/itex]
    where [itex]\Delta L= (100 - 1.65)\% L_s[/itex]

    Is it ok?
     
    Last edited: Oct 4, 2011
  2. jcsd
  3. Oct 7, 2011 #2

    RHK

    User Avatar

    Anyone can suggest if it's the correct way?
     
  4. Oct 7, 2011 #3

    RHK

    User Avatar

    I'm sorry: the correct eqaution is not (as reported):
    but: [itex]\Delta L= 4\pi(R_s^2 - R_{planet}^2) \sigma T_s^4 [/itex]

    What about this?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook