Host’s stars and habitability - I. Impact of stellar parameters

Host’s stars and habitability - I. Impact of stellar parameters

F. Gallet1, C. Charbonnel1; 2, L. Amard1; 3, A. Palacios3, S. Brun4, and S. Mathis4

 

ContextWith more than 1500 detected and confirmed exoplanets within a large range of dierent configurations of size, mass, chemical composition and distance from their host’s star, the probability to find a planet that look like the Earth increases every year. While it is clear that being in the habitable zone did not imply being habitable, “life” indeed requires strong favourable conditions, a systematic study of the evolution of the habitable zone is required to account for its dependence upon stellar parameters.

AimsIn this article we aim to provide the community with a systematic study of the evolution of the habitable zone as a function of the stellar mass, metallicity, rotation, and habitable zone limits prescriptions to assess the impact of these parameters on the habitable zone limits and duration of the continuously habitable zone.

MethodsUsing the STAREVOL stellar structure evolution model that includes the most up to date physical mechanisms, we studied the habitable zone and continuously habitable zone limits evolution.

ResultsThe mass and metallicity are the stellar parameters that have the most dramatic eect on the habitable zone limits. Conversely, stellar rotation have only a marginal eect on these limits and does not modify the width of the habitable zone. The evolution of the habitable zone limits is also well correlated to the evolution of the stellar activity (through the Rossby number) and appears to be quite close from the stellar surface when the stellar activity is at its lowest. This should then favour the development of “life” during the early stage of the continuously habitable zone phase.

ConclusionsWhile the habitable zone is very sensitive to the stellar mass and metallicity, these quantities are dicult to be estimated from the observations. Measuring the habitable zone is then quite hard and one should be very careful when evaluating this quantity for newly detected exoplanets. In this article we provide the main dependences of the habitable zone limits on the stellar parameters. These results could be used as physical inputs for a first order estimation of exoplanetary habitability.