Giant planets around young M-dwarfs

Henry Ngo (Caltech)

D Mawet, B Bowler, J Wang, O Absil, M Bottom, E Choquet, C Gomez, E Huby, L Hillenbrand,

R Jensen-Clem, T Meshkat, M Reggiani, E Serabyn

Semimajor axis (AU)

Plan

et M

ass

(MJu

p)

Transit Radial Velocity Microlensing

Direct Imaging

Jupiter

Giant Planet Formation

1) Core formation

2) Hydrostatic growth

3) Runaway accretion

4) Planet contracts

Source of gas is removed

Core reaches ~10 Earth masses

Core mass ≈ envelope mass

(and emits energy we can detect)

Challenges •  Gather enough solids for critical mass •  Reach critical mass before gas dissipates

1) Core formation

2) Hydrostatic growth

3) Runaway accretion

4) Planet contracts

Source of gas is removed

Core reaches ~10 Earth masses

Core mass ≈ envelope mass

Batygin et al. (2016)

Enough solids? Minimum Mass Extrasolar Nebula Chiang & Laughlin (2013) Efficient enough? Compact multi-planet systems Boley et al. (2016) Batygin et al. (2016)

in situ formation

formation then migration

Enough solids? Increase in solids at ice line Lin et al. (1996) Efficient enough? “Pebble accretion” Lambrechts & Johansen (2012)

Predictions •  in situ formation: additional smaller planets, P < 100 d

•  ice line formation & migration: planet reservoir?

iceline(severalAU)

Young planets Old planets

(observed today)

Predictions •  in situ formation: additional smaller planets, P < 100 d

•  ice line formation & migration: planet reservoir?

iceline(severalAU)

Young planets Old planets

(observed today) Q: Does this ice-line planet reservoir exist?

Finding young planets at the ice lines

•  Target young moving group members

Bowler (2016): Recent efforts to find low-mass members creates large number of potential direct imaging targets

Knowing age is important

Bowler (2016)

Maximize detection ability

Bowler (2016)

Young stars Nearby stars Smaller stars

= better contrast

Detection Probability Sample of 200 late K / M-dwarf (<d> = 40 pc)

L’ vortex on Keck/NIRC2 (IWA = 80 mas)Expected yield (microlensing): 10 planets

Sample star in beta Pic43 pc, 20 Myr, rmag ~9.5

Science image, flattened ADI+PCA processed

(VIP; Gomez Gonzalez et al. 2016)

~ 3”

Sample star in beta Pic43 pc, 20 Myr, rmag ~9.5

5x10-4 contrast @ 0.5”3 MJ @ 22 AU

2x10-3 contrast @ 0.3”6 MJ @ 13 AU

Expect improved contrast down to ~ 0.1” with RDI correction

Progress (since Oct 2015) Schedule

Planned:

4 semesters

Completed: 2 semesters

Next semester (2016B) already

allocated.

Apply for final semester (2017A)

next month

Summary •  Two hot Jupiter formation models –  in situ: predicts additional small planets with

periods < 100 days – migration: predicts reservoir of young planets

near ice line •  Survey of ~200 M-dwarfs in L-band on

Keck/NIRC2 with vortex to confirm or refute ice line planet reservoir

•  Reggiani/Absil: Southern survey on VLT