TY - JOUR
T1 - The Detectability of Radio Auroral Emission from Proxima b
AU - Burkhart, Blakesley
AU - Loeb, Abraham
N1 - Funding Information: We are grateful for valuable discussions with Cecilia Garraffo, Laura Kreidberg, and Zachary Slepian. B.B. acknowledges generous support from the NASA Einstein Postdoctoral Fellowship and the joint Sub-millimeter Array/ Institute for Theory and Computation Postdoctoral Fellowship. This work was supported in part by a grant from the Breakthrough Prize Foundation. Publisher Copyright: © 2017. The American Astronomical Society. All rights reserved.
PY - 2017/11/1
Y1 - 2017/11/1
N2 - Magnetically active stars possess stellar winds whose interactions with planetary magnetic fields produce radio auroral emission. We examine the detectability of radio auroral emission from Proxima b, the closest known exosolar planet orbiting our nearest neighboring star, Proxima Centauri. Using the radiometric Bode's law, we estimate the radio flux produced by the interaction of Proxima Centauri's stellar wind and Proxima b's magnetosphere for different planetary magnetic field strengths. For plausible planetary masses, Proxima b could produce radio fluxes of 100 mJy or more in a frequency range of 0.02-3 MHz for planetary magnetic field strengths of 0.007-1 G. According to recent MHD models that vary the orbital parameters of the system, this emission is expected to be highly variable. This variability is due to large fluctuations in the size of Proxima b's magnetosphere as it crosses the equatorial streamer regions of dense stellar wind and high dynamic pressure. Using the MHD model of Garraffo et al. for the variation of the magnetosphere radius during the orbit, we estimate that the observed radio flux can vary nearly by an order of magnitude over the 11.2-day period of Proxima b. The detailed amplitude variation depends on the stellar wind, orbital, and planetary magnetic field parameters. We discuss observing strategies for proposed future space-based observatories to reach frequencies below the ionospheric cutoff (∼10 MHz), which would be required to detect the signal we investigate.
AB - Magnetically active stars possess stellar winds whose interactions with planetary magnetic fields produce radio auroral emission. We examine the detectability of radio auroral emission from Proxima b, the closest known exosolar planet orbiting our nearest neighboring star, Proxima Centauri. Using the radiometric Bode's law, we estimate the radio flux produced by the interaction of Proxima Centauri's stellar wind and Proxima b's magnetosphere for different planetary magnetic field strengths. For plausible planetary masses, Proxima b could produce radio fluxes of 100 mJy or more in a frequency range of 0.02-3 MHz for planetary magnetic field strengths of 0.007-1 G. According to recent MHD models that vary the orbital parameters of the system, this emission is expected to be highly variable. This variability is due to large fluctuations in the size of Proxima b's magnetosphere as it crosses the equatorial streamer regions of dense stellar wind and high dynamic pressure. Using the MHD model of Garraffo et al. for the variation of the magnetosphere radius during the orbit, we estimate that the observed radio flux can vary nearly by an order of magnitude over the 11.2-day period of Proxima b. The detailed amplitude variation depends on the stellar wind, orbital, and planetary magnetic field parameters. We discuss observing strategies for proposed future space-based observatories to reach frequencies below the ionospheric cutoff (∼10 MHz), which would be required to detect the signal we investigate.
KW - planet-star interactions
KW - planets and satellites: magnetic fields
KW - stars: low-mass
KW - stars: winds, outflows
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U2 - https://doi.org/10.3847/2041-8213/aa9112
DO - https://doi.org/10.3847/2041-8213/aa9112
M3 - Article
VL - 849
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 1
M1 - L10
ER -