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

B KIC 7917485b Discovery

  1. Oct 6, 2016 #1
    This particular exoplanet I think deserves a special thread because of the method used to make its discovery. This exoplanet is unusual in that it is one of the few exoplanets discovered orbiting a spectral type A star, and because it was the only one discovered using the pulsations of the star's helium layer.
    KIC 7917485
    M = 1.63
    R = 2.16
    L = 9.9
    Teff = 7,067°K ± 192°K

    KIC 7917485b
    MJ = 11.8 (+0.8, -0.6)
    Orbit = 840 ± 20 days (2.06 ± 0.04 AU est.)

    According to Kopparapu, et al. (2014) the "conservative" Habitable Zone for this star is between 2.779 AU and 4.798 AU. The snow/frost line (160°K) for this star is approximately 13.62 AU. Considering such an exoplanet could not have formed any closer, it would have had to migrate inward quite a distance.

    Source:
    A planet in an 840-d orbit around a Kepler main-sequence A star found from phase modulation of its pulsations - arXiv 1608.02945
     
  2. jcsd
  3. Oct 7, 2016 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    So basically pulsar timing, but with stellar oscillations instead of pulsar pulses. Interesting concept, and it requires an amazing long-term stability of the oscillation. The star moves by just 13 light seconds in the 2.5 year orbit of the planet. It corresponds to a radial velocity amplitude of 160 m/s, which should be obvious for all radial velocity searches - if they look at this star.
     
  4. Oct 7, 2016 #3
    Not pulsar timing, since: 1) This star will not end up as a pulsar or neutron star when it dies; and 2) Pulsar timing is caused by a completely different method. This exoplanet was discovered using the helium layer phase modulation within the variable star and then converted the time delays into radial velocities using the formula from Murphy & Shibahashi (2015).

    Source:
    Deriving the orbital properties of pulsators in binary systems through their light arrival time delays - Oxford Journals, MNRAS, Volume 450, Issue 4, Pp. 4475-4485 (arXiv free reprint)
     
  5. Oct 7, 2016 #4

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    The timing is the common feature.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: KIC 7917485b Discovery
Loading...