toward direct studies of habitable exoplanets · markus janson (stockholm university) the planet...
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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)