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Coherent radio emission from a quiescent red dwarf indicative of star-planet interaction | H. K. Vedantham
; J. R. Callingham
; T. W. Shimwell
; C. Tasse
; B. J. S. Pope
; M. Bedell
; I. Snellen
; P. Best
; M. J. Hardcastle
; M. Haverkorn
; A. Mechev
; S. P. O'Sullivan
; H. J. A. Röttgering
; G. J. White
; | Date: |
20 Feb 2020 | Abstract: | Low frequency ($
ulesssim 150,$MHz) stellar radio emission is expected to
originate in the outer corona at heights comparable to and larger than the
stellar radius. Such emission from the Sun has been used to study coronal
structure, mass ejections, space-weather conditions around the planets (Schwenn
2006). Searches for low-frequency emission from other stars have only detected
a single active flare-star (Lynch et al. 2017) that is not representative of
the wider stellar population. Here we report the detection of low-frequency
radio emission from a quiescent star, GJ 1151--- a member of the most common
stellar type (red dwarf or spectral class M) in the Galaxy. The characteristics
of the emission are similar to those of planetary auroral emissions (Zarka
1998) (e.g. Jupiter’s decametric emission), suggesting a coronal structure
dominated by a global magnetosphere with low plasma density. Our results show
that large-scale currents that power radio aurorae operate over a vast range of
mass and atmospheric composition, ranging from terrestrial planets to
main-sequence stars. The Poynting flux required to produce the observed radio
emission cannot be generated by GJ 1151’s slow rotation, but can originate in a
sub-Alfv’{e}nic interaction of its magnetospheric plasma with a short-period
exoplanet. The emission properties are consistent with theoretical expectations
(Zarka 2007; Lanza 2009; Saur et al. 2013; Turnpenney et al. 2018) for
interaction with an Earth-size planet in a $sim 1-5$ day-long orbit. | Source: | arXiv, 2002.8727 | Services: | Forum | Review | PDF | Favorites |
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