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Help With A Few Questions?

  1. Mar 17, 2008 #1
    Can someone help me understand some homework questions? I'm stuck on these last 5 out of 30.

    The star Pegasi (RA = 22h 57m, Dec.=+20.75) is of spectral class G2 V (temperature of around 5800 K). It's distance is 50 ly from us and has a planet (150 earth masses) orbiting it with a semi-major axis of 0.052 AU. The star is about 1 solar mass, and its luminosity is about 1.3 times that of the sun and absolute magnitude of about 4.0

    Okay, on to the questions I'm not understanding.

    1) How do I determine the angular size of the planet's orbital diameter (Arc seconds)?
    2) What is the wavelength and frequency of the peak in 51 Pegasi's black body curve and what radiation is it?
    3) What's the star's parallax?
    4) What's the star's apparent magnitude
    5)What is the sidereal time on March 7 at 4:00 pm?

    I'd appreciate it if someone had time to explain!
  2. jcsd
  3. Mar 17, 2008 #2
    Last edited: Mar 17, 2008
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