Identifying the Best Places to Search for Life

A talk I gave at the Breakthrough Listen North American Community Workshop in Green Bank, WV.

Transcript

1. Tom Barclay NASA Ames Research Center Breakthrough Listen October 6, 2016 Identifying the Best Places to Search for Life
2. Tom Barclay NASA Ames Research Center Breakthrough Listen October 6, 2016 Identifying the Best Places to Search for Life
3. Takeaways From Kepler we know small planets are common K2 and TESS will yield many promising targets rocky, habitable zone planets Using planet formation models, we can predict which of these planets are the best places to search for life
4. Exoplanet Detections, 1995-2009 Radius Relative to Earth Orbital Period in days Earth Jupiter
5. Coughlin et al. 2015 Exoplanet Detections, 1995-2015 Radius Relative to Earth Orbital Period in days
6. 0.5-0.7 0.7 - 1 1 – 1.4 1.4 - 2 2 – 2.8 2.8 - 4 4 – 5.7 5.7 - 8 8 - 11 11 - 16 16 - 23 Planet Size (Earth=1) Fraction Observed Sizes not seen in our Solar System 55 165 381 520 567 268 94 54 53 39 17
7. 1 – 1.4 1.4 - 2 2 – 2.8 2.8 - 4 4 – 5.7 5.7 - 8 8 - 11 11 - 16 16 - 23 Planet Size (Earth=1) Fraction Observed Sizes not seen in our Solar System
8. Sizes not seen in our Solar System 1 – 1.4 1.4 - 2 2 – 2.8 2.8 - 4 4 – 5.7 5.7 - 8 8 - 11 11 - 16 16 - 23 Planet Size (Earth=1) Average Number of Planets per Star
9. Systematic Errors vs. Statistical Errors Burke et al. 2015
10. More small planets around small stars Mulders et al. 2014
12. Current Status Senior Review 2014 Senior Review 2016
13. Kepler prime versus K2 target stars Huber et al. 2016 41% K&M dwarfs 16% K&M dwarfs
16. Finding Exoplanet Targets for Followup
17. Finding Exoplanet Targets for Followup
18. 18 Transiting Exoplanet Survey Satellite NASA Explorer Mission TESS searching the whole sky to find hundreds of small exoplanets amenable to detailed characterization
19. 19 Animation created by Zach Berta-Thompson
20. Collapse of molecular cloud core proto-star + disk (Shu, Adams, & Lizano 1987) Planets Form From Disks
21. Early stage dust grains planetesimals ~ μm ~1-10 km Middle stage planetesimals planetary embryos ~103 km Late stage embryos planets Classical Solar Nebular Theory
22. Collisions • Shape of the final architecture of planetary systems • Alter bulk compositions (e.g. Mercury, Earth-moon) • Affect potential habitability - alter spin and rotation rates (weather) - strip off oceans and atmospheres - wipe out life Timing of final giant collision (eg. Moon forming impacts) is important because you need enough time and enough residual material for Earth-like planets to accrete and retain water and other volatiles
23. Jupiter analogs are likely scarce! Occurrence Rates of Jupiter (RV + Transits) ~ 6% (Wittenmyer et al. 2016)
24. Jupiter+Saturn 24 No giant planets
25. The Impact of Giant Planets Without giant planets there are more total impacts but fewer giant impacts. However giant impacts happen much later
26. 26 No giant planets With giant planets With giant planets, some Earth’s are wet, others are dry Without giant planets, all Earth’s are wet Water Delivery
27. • Giant planet architectures are just an example of the power of this work • We can apply the same modeling efforts to explore other external factors, e.g. - host star - stellar binary companions - initial disk chemistry
28. Takeaways From Kepler we know small planets are common K2 and TESS will yield many promising targets rocky, habitable zone planets Using planet formation models, we can predict which of these planets are the best places to search for life