A colloquium I gave a UC Berkeley. This was hastily thrown together as I was a replacement speaker. Charlie Townes (inventor of the laser) was sat int he front row.
curves tell us the size and orbital period of the planet. The orbital period can be used to estimate the planet’s surface temperature Brightness of Star Time (days)
somewhere from 0.5 – 3% – We want to look at LOTS of stars • We need very low noise – ideally limited by stellar variability – Go into space far away from the Earth • Observe multiple orbits of the same planet – Stare at the same field continuously for as long as possible So we built a spacecraft and called it Kepler 6
Large planets exhibit high signal to noise transits – We can observe tiny effects (<20 ppm) • This allows us to learn about physical characteristic beyond the radius • Some have RV follow-up – We can test our assumptions on these and apply to others We can look at the brightness variations we see as a function of orbital phase
star owing to a planet • Combination of two effects – one relativistic and one classical Classical • As the star moves towards/away us the light is blue/red-shifted • The spectrum of the star moves in/ out of the Kepler passband the star gets brighter/fainter Relativistic • As star moves towards us the light is beamed in our direction • As it moves away light is beamed in other direction, star gets fainter
Assume phase variations are a combination of a few sinusoidal functions 21 Ellipsoidal variations Doppler beaming Reflection/emission from planet Shown here is a Lambertian phase function
beaming and reflection from TrES-2b. • A radial velocity amplitude consistent with ground based RVs Derived planet mass 27 Photometry Ground-based RVs Barclay et al., 2012
darkest known exoplanet – The geometric albedo found by Kipping et al. is 0.025±0.007 • We find a geometric albedo of 0.014±0.003 The darkest known exoplanet is even darker than thought 28 (2011) Barclay et al., submitted
required exquisite follow-up observation • Follow-up was used in a BLENDER analysis Unfortunately this source is saturated which makes centoiding only good to 1 pix BLENDER explores false positive scenarios that could mimic a transit
false positive rate to the probability that the source is a real planet Largest candidate in the system in undoubtedly a planet – Kepler-37d The middle planet is a planet orbiting the target with a probability >99.95% – Kepler-37c
planet candidates as small as KOI-245.03 – no comparison for planet prior We assume the occurrence rate of small planets is the same as for Earth-size planet With this assumption KOI-245.03 is a planet with a probability >99.95% – Kepler-37b
the Sun a star • Is a nearly round shape • Has cleared its neighborhood The minimum mass for Kepler-37b is around 0.01 M ⊕ Therefore the planet must be ‘a nearly round shape’ Soter 2006
planets • Kepler-69b – Porb=13 days – 2.3 Rearth • Kepler-69c – Porb=242 days – 1.74 Rearth • Detection very difficult because of image artifacts Barclay et al, 2013