An Earth-like stellar wind environment for Proxima Centauri c. (arXiv:2009.07266v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Alvarado_Gomez_J/0/1/0/all/0/1">Julián D. Alvarado-Gómez</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Drake_J/0/1/0/all/0/1">Jeremy J. Drake</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Garraffo_C/0/1/0/all/0/1">Cecilia Garraffo</a> (3 and 2), <a href="http://arxiv.org/find/astro-ph/1/au:+Cohen_O/0/1/0/all/0/1">Ofer Cohen</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Poppenhager_K/0/1/0/all/0/1">Katja Poppenhäger</a> (1 and 5), <a href="http://arxiv.org/find/astro-ph/1/au:+Yadav_R/0/1/0/all/0/1">Rakesh K. Yadav</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Moschou_S/0/1/0/all/0/1">Sofia P. Moschou</a> (2) ((1) Leibniz Institute for Astrophysics Potsdam, (2) Center for Astrophysics | Harvard & Smithsonian, (3) Harvard University, (4) University of Massachusetts Lowell, (5) University of Potsdam)
A new planet has been recently discovered around Proxima Centauri. With an
orbital separation of $sim$$1.44$ au and a minimum mass of about $7$
$M_{oplus}$, Proxima c is a prime direct imaging target for atmospheric
characterization. The latter can only be performed with a good understanding of
the space environment of the planet, as multiple processes can have profound
effects on the atmospheric structure and evolution. Here, we take one step in
this direction by generating physically-realistic numerical simulations of
Proxima’s stellar wind, coupled to a magnetosphere and ionosphere model around
Proxima c. We evaluate their expected variation due to the magnetic cycle of
the host star, as well as for plausible inclination angles for the exoplanet
orbit. Our results indicate stellar wind dynamic pressures comparable to
present-day Earth, with a slight increase (by a factor of 2) during high
activity periods of the star. A relatively weak interplanetary magnetic field
at the distance of Proxima c leads to negligible stellar wind Joule heating of
the upper atmosphere (about $10%$ of the solar wind contribution on Earth) for
an Earth-like planetary magnetic field ($0.3$ G). Finally, we provide an
assessment of the likely extreme conditions experienced by the exoplanet
candidate Proxima d, tentatively located at $0.029$ au with a minimum mass of
$0.29$ $M_{oplus}$.
A new planet has been recently discovered around Proxima Centauri. With an
orbital separation of $sim$$1.44$ au and a minimum mass of about $7$
$M_{oplus}$, Proxima c is a prime direct imaging target for atmospheric
characterization. The latter can only be performed with a good understanding of
the space environment of the planet, as multiple processes can have profound
effects on the atmospheric structure and evolution. Here, we take one step in
this direction by generating physically-realistic numerical simulations of
Proxima’s stellar wind, coupled to a magnetosphere and ionosphere model around
Proxima c. We evaluate their expected variation due to the magnetic cycle of
the host star, as well as for plausible inclination angles for the exoplanet
orbit. Our results indicate stellar wind dynamic pressures comparable to
present-day Earth, with a slight increase (by a factor of 2) during high
activity periods of the star. A relatively weak interplanetary magnetic field
at the distance of Proxima c leads to negligible stellar wind Joule heating of
the upper atmosphere (about $10%$ of the solar wind contribution on Earth) for
an Earth-like planetary magnetic field ($0.3$ G). Finally, we provide an
assessment of the likely extreme conditions experienced by the exoplanet
candidate Proxima d, tentatively located at $0.029$ au with a minimum mass of
$0.29$ $M_{oplus}$.
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