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NASA Ames
NASA Ames Kepler Mission Goals Determine the percentage of - - PowerPoint PPT Presentation
NASA Ames Kepler Mission Goals Determine the percentage of - - PowerPoint PPT Presentation
NASA Ames Kepler Mission Goals Determine the percentage of terrestrial and larger planets that are in or near the habitable zone of a wide variety of stars Determine the properties of those stars that harbor planetary
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Kepler Mission Goals
- “Determine the percentage of terrestrial and larger
planets that are in or near the habitable zone of a wide variety of stars”
- …
- “Determine the properties of those stars that
harbor planetary systems.”
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Kepler: exoplanet statistics
Earth-sized habitable zone planet around sun-like star:
- 0.5 % transit probability
- ~10% (?) detection efficiency
- 10% planet occurrence rate
Need to monitor 20,000 stars to find a single planet!
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NASA Ames
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Planet occurrence rate
- Average number of planets per star
(< fraction of stars with planets) ~1 planet per star ~10% stars have earth-sized planet in the habitable zone. Why occurrence rate?
– Exoplanet discovery mission yield – Planet Formation /Evolution
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Why Exoplanet Host Star Properties?
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Why Exoplanet Host Star Properties?
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Why Exoplanet Host Star Properties?
Fischer & Valenti 2005
Stellar-mass dependencies can constrain planet formation mechanisms More giant planets around metal-rich stars
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Why Exoplanet Host Star Properties?
Johnson et al. 2007
Stellar-mass dependencies can constrain planet formation mechanisms More giant planets around more massive stars
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Kepler: Most planets are small
Fressin et al. 2013. RV: Howard et al. 2010
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Talk Outline
- 1. Planet Population
- 2. Stellar mass
- 3. Stellar metallicity (LAMOST!)
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Kepler: Exoplanet Transits
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Planet population: Occurrence rate
- 1. Stars
- 2. Planets
- 3. Detection efficiency
& Transit probability
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- 1. Stars
Huber et al. 2014, Dressing & Charbonneau 2013
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- 2. Planets
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- 3. Detection efficiency
S/N ratio: transit depth stellar noise
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- 3. Detection efficiency
Geometric Transit Probability
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- 1. Stars
Huber et al. 2014, Dressing & Charbonneau 2013
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M dwarfs have more planets
Mulders 2017 under review
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More small planets, fewer giants
Mulders et al. 2015b
4x 2x
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Comparison with disk solids
Mulders et al. 2015c. Disk mass: Pascucci et al. 2016
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Sunlike Star Red Dwarf Planet Migration Protoplanetary Disk Observed with Kepler
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Dependence on Metallicity
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Host Star Metallicity (CPS)
Bucchave et al. 2014
Trend vanishes!
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Metallicity Dependence of sub-Neptunes
Wang&Fischer 2015 Winn+ 2017 Buchhave+ 2014 Dawson+ 2015 Mulders+ 2016 Dong+ 2017 RV: Sousa+ 2008 No Trend Strong Trend RV: Giant planets
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LAMOST Stellar Metallicities
[Fe/H] from ROTFIT pipeline (Frasca et al. 2016)
- 51,385 stars
- 20,863 MS stars
- 665 planet hosts
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Metallicity versus orbital period
Mulders et al. 2016
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Metallicity versus orbital period
Mulders et al. 2016, also Dong et al. 2017
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Small Impact on Planet population
Mulders et al. 2016
90% 30% 10%
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Small Impact on Planet population
Mulders et al. 2016, Adibekyan et al. 2016
Trend here? (1.5 sigma) 3 sigma? -> 100,000 stars DR3/4/5+
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Future Outlook
- Transit surveys to study exoplanet populations
(Kepler, K2, TESS)
- Stellar characterization needed for determining
planet parameters
- Stellar parameters of non-planet hosts to calculate
planet occurrence rates
- LAMOST provides additional information