CHARACTERIZING THE COOLER KOIS

PLANETS AROUND MID M DWARFS

Benjamin Montet (Caltech/Harvard)K2 Science Conference

4 November 2015

@benmontet

THANKS TO COLLABORATORS!

Dan Foreman-Mackey (UW)David Hogg (NYU)John Johnson (Harvard)Tim Morton (Princeton)Yutong Shan (Harvard)Andrew Vandenburg (Harvard)And many others…

WE ALREADY UNDERSTAND PLANETS AROUND M DWARFS

WE ALREADY UNDERSTAND PLANETS AROUND M DWARFS

WE ALREADY UNDERSTAND PLANETS AROUND M DWARFS

WE ALREADY UNDERSTAND PLANETS AROUND M DWARFS

WE DON’T UNDERSTAND PLANETS AROUND M DWARFS

WE DON’T UNDERSTAND PLANETS AROUND M DWARFS

GiantsDwarfs

WE DON’T UNDERSTAND PLANETS AROUND M DWARFS

GiantsDwarfs

WE DON’T UNDERSTAND PLANETS AROUND M DWARFS

GiantsDwarfs

WE DON’T UNDERSTAND PLANETS AROUND M DWARFS

GiantsDwarfs

WE DON’T UNDERSTAND PLANETS AROUND M DWARFS

GiantsDwarfs

WE DON’T UNDERSTAND PLANETS AROUND M DWARFS

GiantsDwarfs

WE DON’T UNDERSTAND PLANETS AROUND M DWARFS

ABOUT 85% OF KEPLER’S M DWARFS ARE M0-M1 DWARFS

MOST STARS IN THE GALAXY ARE MID-M DWARFS

K2 IS PROBING THESE!

M DWARFS ARE NEARBY, APPROXIMATELY ISOTROPIC

M DWARFS ARE NEARBY, APPROXIMATELY ISOTROPIC

M DWARFS ARE NEARBY, APPROXIMATELY ISOTROPIC

K2

KEPLER OBSERVED 300 M2-8 DWARFS

K2 WILL OBSERVE 3,500 IN FIELDS 4 AND 5

ALONE

PLANETS AROUND M DWARFS

Montet et al. (2015b)

ConfirmedCandidate

False PositiveDFM et al. (2015)

PLANETS AROUND M DWARFS

ConfirmedCandidate

False PositiveMontet et al. (2015b)

DFM et al. (2015)

STELLAR CHARACTERIZATION

Statistical, with isochrones (Tim Morton, on github)

Data-driven, with TripleSpec, SpeX, and broadband photometry

PLANET VALIDATION

Statistical, with vespa (Tim Morton, on github)

Data-driven, with Keck/NIRC2, P200/PHARO,

archival imaging with POSS, SDSS

PLANET VALIDATION

K2-18b• 33 day period (from C1)

• 2.24±0.23 Earth-radius planet around an M2.8 dwarf

• Equilibrium temperature of 272±15 K

• GJ1214b analog with Earthlike insolation—useful for composition studies?

MID-M PLANET HOSTS IN C4

MID-M PLANET HOSTS IN C4

Two of these host stars have colors consistent

with M4

Only three such planetary systems in

Kepler!

WHERE ARE THE M DWARF PLANETS?

WHERE ARE THE M DWARF PLANETS?

Morton and Swift 2014

WHERE ARE THE M DWARF PLANETS?

• Strong falloff in expected planet yield with decreasing sensitivity

• Stars drawn from the same population in K2 and Kepler

• Stars are typically less massive, especially in C4/5

• Need to understand completeness well before we claim a lower occurrence

• Injections important, before any detrending processes!

WE DON’T ACTUALLY UNDERSTAND THE POPULATION OF PLANETS

AROUND M DWARFS

BUT K2 IS HELPING US LEARN

WHERE ARE THE M DWARF PLANETS?

• Strong falloff in expected planet yield with decreasing sensitivity

• Stars drawn from the same population in K2 and Kepler

• Stars are typically less massive, especially in C4/5

• Need to understand completeness well before we claim a lower occurrence

• Injections important, before any detrending processes!

MID-M PLANET HOSTS IN C5?