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Title: THE SPACE WEATHER OF PROXIMA CENTAURI b

Abstract

A planet orbiting in the “habitable zone” of our closest neighboring star, Proxima Centauri, has recently been discovered, and the next natural question is whether or not Proxima b is “habitable.” Stellar winds are likely a source of atmospheric erosion that could be particularly severe in the case of M dwarf habitable zone planets that reside close to their parent star. Here, we study the stellar wind conditions that Proxima b experiences over its orbit. We construct 3D MHD models of the wind and magnetic field around Proxima Centauri using a surface magnetic field map for a star of the same spectral type and scaled to match the observed ∼600 G surface magnetic field strength of Proxima. We examine the wind conditions and dynamic pressure over different plausible orbits that sample the constrained parameters of the orbit of Proxima b. For all the parameter space explored, the planet is subject to stellar wind pressures of more than 2000 times those experienced by Earth from the solar wind. During an orbit, Proxima b is also subject to pressure changes of 1–3 orders of magnitude on timescales of a day. Its magnetopause standoff distance consequently undergoes sudden and periodic changes by amore » factor of 2–5. Proxima b will traverse the interplanetary current sheet twice each orbit, and likely crosses into regions of subsonic wind quite frequently. These effects should be taken into account in any physically realistic assessment or prediction of its atmospheric reservoir, characteristics, and loss.« less

Authors:
;
Publication Date:
OSTI Identifier:
22654147
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 833; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CHARGES; FORECASTING; LOSSES; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MAGNETOPAUSE; ORBITS; PERIODICITY; PLANETS; SATELLITES; SOLAR WIND; SPACE; STARS; STELLAR WINDS; SURFACES

Citation Formats

Garraffo, C., Drake, J. J., and Cohen, O., E-mail: cgaraffo@cfa.harvard.edu. THE SPACE WEATHER OF PROXIMA CENTAURI b. United States: N. p., 2016. Web. doi:10.3847/2041-8205/833/1/L4.
Garraffo, C., Drake, J. J., & Cohen, O., E-mail: cgaraffo@cfa.harvard.edu. THE SPACE WEATHER OF PROXIMA CENTAURI b. United States. doi:10.3847/2041-8205/833/1/L4.
Garraffo, C., Drake, J. J., and Cohen, O., E-mail: cgaraffo@cfa.harvard.edu. Sat . "THE SPACE WEATHER OF PROXIMA CENTAURI b". United States. doi:10.3847/2041-8205/833/1/L4.
@article{osti_22654147,
title = {THE SPACE WEATHER OF PROXIMA CENTAURI b},
author = {Garraffo, C. and Drake, J. J. and Cohen, O., E-mail: cgaraffo@cfa.harvard.edu},
abstractNote = {A planet orbiting in the “habitable zone” of our closest neighboring star, Proxima Centauri, has recently been discovered, and the next natural question is whether or not Proxima b is “habitable.” Stellar winds are likely a source of atmospheric erosion that could be particularly severe in the case of M dwarf habitable zone planets that reside close to their parent star. Here, we study the stellar wind conditions that Proxima b experiences over its orbit. We construct 3D MHD models of the wind and magnetic field around Proxima Centauri using a surface magnetic field map for a star of the same spectral type and scaled to match the observed ∼600 G surface magnetic field strength of Proxima. We examine the wind conditions and dynamic pressure over different plausible orbits that sample the constrained parameters of the orbit of Proxima b. For all the parameter space explored, the planet is subject to stellar wind pressures of more than 2000 times those experienced by Earth from the solar wind. During an orbit, Proxima b is also subject to pressure changes of 1–3 orders of magnitude on timescales of a day. Its magnetopause standoff distance consequently undergoes sudden and periodic changes by a factor of 2–5. Proxima b will traverse the interplanetary current sheet twice each orbit, and likely crosses into regions of subsonic wind quite frequently. These effects should be taken into account in any physically realistic assessment or prediction of its atmospheric reservoir, characteristics, and loss.},
doi = {10.3847/2041-8205/833/1/L4},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 1,
volume = 833,
place = {United States},
year = {2016},
month = {12}
}