Toward direct studies of habitable exoplanets · Markus Janson (Stockholm University) The planet...

Toward direct studies of habitable exoplanets

Markus Janson (Stockholm University)

The planet beta Pic b

Lagrange et al. (2009) ESO composition

A-type star with prominent debris

disk

Planet mass is ~10 Mjup

Planet semi-major axis is ~8-9 AU

Easy to explain with in-situ formation by

core accretion (Bonnefoy et al.

2013)

High dispersion, high contrast

Snellen et al. (2014, 2015)

The alpha Cen system

P. Kervella

Distance: 1.3 pc (4.4 ly)

Masses – A: 1.1 Msun B: 0.9 Msun

Proxima: 0.12 Msun

Orbits – A-B: 80 yr

AB-Proxima: 550 kyr

Approximately Solar age (~5 Gyr)

Distance is critical

Required telescope size D scales with distance d

D ~ d

Distance is critical

Required telescope size D scales with distance d

D ~ d

$ ~ D2.5-3 ~ d2.5-3

Distance is critical

Required telescope size D scales with distance d

D ~ d

$ ~ D2.5-3 ~ d2.5-3

ε Eri versus α Cen: 3.2 pc (10.8 ly) versus 1.3 pc (4.4 ly)

-> ~10-15 times higher $ for ε Eri

Proxima Centauri b

Anglada-Escude et al. (2016)

The M-star environment

Stellar wind pressure: 2000 x Earth

R.K. Sepetjian

Flares (energy received): 4000 x Earth, 8 times per year

X-ray dosage: 400 x Earth

Tidally locked -> probably no planetary magnetic field

The STARE concept

Janson et al. (2017)

Future ESO-ELT

STARE science

Janson et al. (2017)

Demory et al. (2015)