Imperial College London
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DrSubhanjoyMohanty

Faculty of Natural Sciences, Department of Physics

Reader in Astrophysics
 
 
 
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Contact

 

+44 (0)20 7594 7553s.mohanty

 
 
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Location

 

1010 BlackettBlackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Owen:2016:mnras/stw959,
author = {Owen, JE and Mohanty, S},
doi = {mnras/stw959},
journal = {Monthly Notices of the Royal Astronomical Society},
pages = {4088--4108},
title = {Habitability of terrestrial-mass planets in the HZ of M Dwarfs - I. H/He-dominated atmospheres},
url = {http://dx.doi.org/10.1093/mnras/stw959},
volume = {459},
year = {2016}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - The ubiquity of M dwarfs, combined with the relative ease of detecting terrestrial-mass planets around them, has made them prime targets for finding and characterizing planets in the ‘habitable zone’ (HZ). However, Kepler finds that terrestrial-mass exoplanets are often born with voluminous H/He envelopes, comprising mass-fractions (Menv/Mcore) 1 per cent. If these planets retain such envelopes over Gyr time-scales, they will not be ‘habitable’ even within the HZ. Given the strong X-ray/UV fluxes of M dwarfs, we study whether sufficient envelope mass can be photoevaporated away for these planets to become habitable. We improve upon previous work by using hydrodynamic models that account for radiative cooling as well as the transition from hydrodynamic to ballistic escape. Adopting a template active M dwarf XUV spectrum, including stellar evolution, and considering both evaporation and thermal evolution, we show that: (1) the mass-loss is (considerably) lower than previous estimates that use an ‘energy-limited’ formalism and ignore the transition to Jeans escape; (2) at the inner edge of the HZ, planets with core mass  0.9 M⊕ can lose enough H/He to become habitable if their initial envelope mass-fraction is ∼1 per cent; (3) at the outer edge of the HZ, evaporation cannot remove a ∼1 per cent H/He envelope even from cores down to 0.8 M⊕. Thus, if planets form with bulky H/He envelopes, only those with low-mass cores may eventually be habitable. Cores 1 M⊕, with 1 per cent natal H/He envelopes, will not be habitable in the HZ of M dwarfs.
AU  - Owen,JE
AU  - Mohanty,S
DO  - mnras/stw959
EP  - 4108
PY  - 2016///
SN  - 1365-2966
SP  - 4088
TI  - Habitability of terrestrial-mass planets in the HZ of M Dwarfs - I. H/He-dominated atmospheres
T2  - Monthly Notices of the Royal Astronomical Society
UR  - http://dx.doi.org/10.1093/mnras/stw959
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000379830700052&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - http://hdl.handle.net/10044/1/43881
VL  - 459
ER  -
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