Exoplanet Demographics from Kepler and K2

A talk I gave to Goddard Space Flight Center. This was the Astrophysics Science Division Colloquium

Transcript

1. Tom Barclay NASA Ames Research Center NASA Goddard Space Flight Center December 13, 2016 Exoplanet Demographics from Kepler and K2
3. Detecting Planets
4. The amount of dimming tells us the size of the exoplanet. The time it takes to complete an orbit tells us how far away it is from the star.
5. NASA’s Kepler Mission: What fraction of stars in our galaxy harbor potentially habitable, earth-size planets?
6. * *
7. * * March 6, 2009
8. Turning Pixels into Planets
9. Exoplanet Detections, 1995-2009 Radius Relative to Earth Orbital Period in days Earth Jupiter
10. Coughlin et al. 2015 Exoplanet Detections, 1995-2015 Radius Relative to Earth Orbital Period in days
11. 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 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
12. 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 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
13. Confirmed Habitable Zone Planets New validations from Morton et al. 2016 ApJ 822 86
14. Small planets are more abundant around small stars Mulders et al. 2014
15. Systematic Errors vs. Statistical Errors Burke et al. 2015 ApJ 809 8
16. Astrophysical False Positives Kepler-296, Barclay et al., 2015b
17. Credit: Dan Foreman-Mackay, Davos Stars do stuff! Telescopes do stuff! Detectors do stuff! (Planets do stuff, too!)
18. Oscillations (<15 minutes, <1%) Granulation (15min-2days,<0.1%) Magnetic activity - spots (2days to weeks, <10%)) - flares (stochastic,<few%) Pulsations (mins to yrs, <10s of %) Eclipses (hrs to yrs, <50%) Yikes! Luckily, we are mostly saved by timescales and careful target selection Stars do stuff… Davenport et al. 2014
19. False Alarms Log(Period(days)) 372 days! 3 years of data 4 years of data The team is doing amazing work and most of these are now gone!
20. Kepler Mechanical Failure Pointing requires 3 reaction wheels (x,y,z axes) Kepler launched with 4 = End of Prime Mission Failure #1 in June 2012 Failure #2 in May 2013
22. Balancing Solar Pressure Top-down view
23. Current Status Senior Review 2014 Senior Review 2016
24. Current Status Senior Review 2014 Senior Review 2016 In Progress Supernova-focused
26. Kepler prime versus K2 target stars Huber et al. 2016 41% K&M dwarfs 16% K&M dwarfs
27. Exoplanet Discoveries to Date Coughlin et al. 2015 K2 Candidates
28. Pointing Performance The motion is about a pixel every 6-hours First half of campaign Second half of campaign
29. Discover and Vetting of Exoplanets Planet search Target selection Light curve creation 1 Centroiding Odd/Even Depth Significant Secondary Transit Consistency/Shape Ephemeris Matching Robotic Vetting Tools 2 Catalog of False Positives (including other team’s K2 light curves) 3
30. Centroid Test using K2’s Roll Angle Blue = cadences where we could measure a centroid Red = cadences where we could not measure a centroid
31. Centroid Test to Search for False Positives
32. Centroid Test to Search for False Positives
33. Centroid Test to Search for False Positives
34. Centroid Test to Search for False Positives
35. Discover and Vetting of Exoplanets Planet search algorithms and vetting tools can be leveraged for Transiting Exoplanet Survey Satellite
36. Giants Planets Orbiting Giants Stars
37. We can use asteroseismology to infer stellar properties We can use Gaussian Processes to get around increased noise from granulations K2 will observe 100,000+giants TESS will observe millions If red giant occurrence rates match main-sequence stars, TESS will find 1000s. BUT… We can learn the occurrence rates for planets around red giants Main Sequence star Red giant star Chaplin et al 2013
39. Gaussian Processes 39 Credit to Dan Foreman-Mackey
40. Gaussian Processes 40
41. Gaussian Processes 41
42. GPs and Red Giants 42 Barclay et al 2015a
43. GPs and Red Giants 43 Barclay et al 2015a
44. GPs and Red Giants 44 Barclay et al 2015a
45. GPs and Red Giants 45 Barclay et al 2015a Kepler-91b
46. A second example from K2 46 Grunblatt et al. 2016
47. We can use asteroseismology to infer stellar properties We can use Gaussian Processes to get around increased noise from granulations K2 will observe 100,000+giants TESS will observe millions Huber et al. 2016
48. We can use asteroseismology to infer stellar properties We can use Gaussian Processes to get around increased noise from granulations K2 will observe 100,000+giants TESS will observe millions If red giant occurrence rates match main-sequence stars, TESS will find 1000s. BUT… We can learn the occurrence rates for planets around red giants Barclay et al, in prep
49. We can use asteroseismology to infer stellar properties We can use Gaussian Processes to get around increased noise from granulations K2 will observe 100,000+giants TESS will observe millions If red giant occurrence rates match main-sequence stars, TESS will find 1000s. BUT… We can learn the occurrence rates for planets around red giants
50. Giant Siblings
51. Finding Exoplanets Around Cool Stars 2.0±0.7 planets with Porb 2–25 years Foreman-Mackey et al. 2016 Microlensing surveys are ~consistent Gould et al. 2010, Cassan et al. 2012, Suzuki et al. 2017
52. “The chance magnification of the light from a distant star by the distortion in spacetime due to the mass of a foreground star and its planets” Microlensing & the Hunt for Exoplanets
53. 53 Exoplanet Demographics
54. 9 Microlensing Campaign 9 Spacecraft turned 180 degrees to point at Galactic Bulge
55. 55 K2 Campaign 9
57. Bulge
58. Simultaneous Observations from Earth and Space Obtaining sufficient telescope resources was a key component to a successful campaign and our #1 risk
59. Early Demonstration MOA-2016-BLG-233 Preliminary K2 Reduction by Dun Wang, NYU MOA data from the MOA Collaboration http://www.massey.ac.nz/∼iabond/moa/ alert2016/alert.php Difference Flux (arbitrary units) HJD-2457500 K2 MOA 0 5000 10000 15000 20000 0 5 10 15 20 25 PRELIMINARY
60. Preparation for WFIRST K2 Microlensing experiment will provide early estimates Stay Tuned!
61. A. Kepler has told us that planets are everywhere. B. Finding small planets on long orbital periods is hard D. We can combine observations, theory and modern statistics.