Variable Radio Emission from the Young Stellar Host of a Hot Jupiter

TL;DR

This paper reports the first detection of variable nonthermal radio emission from a young star hosting a hot Jupiter, likely caused by magnetic activity, with implications for star-planet magnetic interactions.

Contribution

It presents the first observation of radio emission from a non-degenerate star with an exoplanet, revealing magnetic activity associated with the star-planet system.

Findings

Detected variable radio emission at 6 GHz from V830 Tau

Emission is nonthermal, likely gyro-synchrotron or synchrotron

Magnetic field strength estimated at >30 G

Abstract

We report the discovery of variable radio emission associated with the T Tauri star, V830 Tau, which was recently shown to host a hot Jupiter companion. Very Large Array observations at a frequency of 6 GHz reveal a detection on 01 May 2011 with a flux density $919 \pm 26\ \mu$Jy, along with non-detections in two other epochs at $<66$ and $<150\ \mu$Jy. Additionally, Very Long Baseline Array observations include one detection and one non-detection at comparable sensitivity, demonstrating that the emission is nonthermal in origin. The emission is consistent with the gyro-synchrotron or synchrotron mechanism from a region with a magnetic field ${\stackrel{\scriptstyle >}{\scriptstyle \sim}} 30$ G, and is likely driven by an energetic event such as magnetic reconnection that accelerated electrons. With the limited data we have, we are not able to place any constraint on the relationship between the radio emission and the rotational or orbital properties of V830 Tau. This is the first detection of radio emission from a non-degenerate star known to host an exoplanet.