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Title: The Detectability of Radio Auroral Emission from Proxima b

Abstract

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 planetarymore » 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.« less

Authors:
;  [1]
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA (United States)
Publication Date:
OSTI Identifier:
22654358
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 849; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; COSMIC RADIO SOURCES; EMISSION; FLUCTUATIONS; INTERACTIONS; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MASS; MHZ RANGE; ORBITS; PLANETS; SATELLITES; SPACE; STARS; STELLAR WINDS

Citation Formats

Burkhart, Blakesley, and Loeb, Abraham. The Detectability of Radio Auroral Emission from Proxima b. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA9112.
Burkhart, Blakesley, & Loeb, Abraham. The Detectability of Radio Auroral Emission from Proxima b. United States. doi:10.3847/2041-8213/AA9112.
Burkhart, Blakesley, and Loeb, Abraham. Wed . "The Detectability of Radio Auroral Emission from Proxima b". United States. doi:10.3847/2041-8213/AA9112.
@article{osti_22654358,
title = {The Detectability of Radio Auroral Emission from Proxima b},
author = {Burkhart, Blakesley and Loeb, Abraham},
abstractNote = {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.},
doi = {10.3847/2041-8213/AA9112},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 849,
place = {United States},
year = {Wed Nov 01 00:00:00 EDT 2017},
month = {Wed Nov 01 00:00:00 EDT 2017}
}