1 / 22

Courtney Dressing Advisor: David Charbonneau All Souls College, Oxford July 4, 2011

Howard et al. 2011: Planet Occurrence within 0.25 AU of Solar-Type Stars from Kepler. Courtney Dressing Advisor: David Charbonneau All Souls College, Oxford July 4, 2011. Kepler February Data Release. Number of target stars: 156,453 (58,041) Number of candidates: 1,235 (438)

amable
Download Presentation

Courtney Dressing Advisor: David Charbonneau All Souls College, Oxford July 4, 2011

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Howard et al. 2011: Planet Occurrence within 0.25 AU of Solar-Type Stars from Kepler Courtney Dressing Advisor: David Charbonneau All Souls College, Oxford July 4, 2011

  2. Kepler February Data Release • Number of target stars: 156,453 (58,041) • Number of candidates: 1,235 (438) • Orbiting 997 (375) stars Solar Subset: Teff = 4100-6100 K log g = 4.0-4.9 Kepmag < 15 Bright Dwarf Sample: Teff = 3600-7100 K

  3. Planet Candidates

  4. Planet Occurrence Rate • Within each grid cell, calculate: • Number of candidates • “Augmented” number of candidates • Number of stars searched • Planet occurrence rate

  5. Augmented Number of Candidates • Number of non-transiting planets with same radius and period as transiting candidates where =probability of transit

  6. Number of Stars Searched • Number of stars for which each transiting planet has SNR > 10

  7. Planet Occurrence Rate Planet Occurrence Rate Augmented # of Planets = # of Stars Searched

  8. Planet Occurrence Rate • Periods <50 days • Radii: 2-32 REarth

  9. Planet Occurrence Rate 2.8 REarth Planet Radius 2 REarth 10 Days 17 Days Period

  10. Dependence on Radius kR= 2.9 +0.5/-0.4 α = -1.92 ± 0.11

  11. Dependence on Period

  12. Dependence on Period Larger planets have shorter cutoff periods and sharper transitions.

  13. Dependence on Spectral Type

  14. Dependence on Spectral Type f0= 0.165±0.011 kT=-0.081±0.011

  15. Possible Explanations for the Trend in Occurrence Rate of Small Planets with Teff • Random errors? • Trend preserved for Teff = 4100-6100 K • Trend preserved after Monte Carlo applying gaussian random deviates to Teff and log g • Systematic stellar radius bias? • Would require log g error of 1.6 dex • Errors in KIC are ~0.25 dex • Systematic metallicity bias? • Errors on [Fe/H] in KIC are ≳0.2 dex (rms) • Cannot be ruled out

  16. Planet Density • More massive planets have more H/He gas • Change at 4.5 ME? Models from Fortney et al. 2007 Solar system Kepler Other surveys

  17. Planet Density • Assume planets with densities above 4 g/cm3 are primarily composed of refractory elements

  18. Mapping Kepler Radii to Masses • Toy density models • Constant density • Piece-wise constant density • Compared to Eta-Earth Survey • Volume-limited survey of 166 GK dwarfs • 35 planets detected around 24 stars • Keck-HIRES • See Howard et al. 2010

  19. Mapping Kepler Radii to Masses • Black: Kepler prediction • Red: Eta-Earth measurement Decreasing density

  20. Mapping Kepler Radii to Masses • Best models have ρ≳4g/cm3 for Rp≲3RE

  21. Summary • Planet occurrence increases with decreasing radius and increasing orbital period • Smaller planets (2-4 RE) are more common around cooler stars (metallicity effect?) • Larger planets have steeper cutoffs at shorter periods than smaller planets • There is a ridge of high planet occurrence from 3 days and 2 RE to 50 days and 4 RE.

  22. Questions?

More Related