Decoding circularly polarized radio

A qualitative illustration showing beamed auroral emission on the scallop-shell star J0508-21, assuming that the star has a multipolar stellar magnetic field and the radio emission is triggered by a possible magnetic interaction with an approximately corotating, evaporating planet that is potentially also responsible for causing dips in the star's optical light curves, Kaur et al. 2024b

Simranpreet Kaur

Institute of Space Sciences (ICE-CSIC), Barcelona

Thursday December 5, 2024, H 11.00 AM – Villa Magliola Seminars room – INAF-OATo

LIVE STREAMING

Abstract

Radio stars are rare, though a few recent studies, based on the cross-matching of different catalogs, are extending the known samples for M dwarfs especially.
The talk will present new findings on the radio emission characteristics of two distinct classes of young stars: the scallop-shell star 2MASS J05082729−2101444 (J0508-21) and the young stellar object [BHB2007]-1.

Both systems exhibit variable circularly polarized radio emission, a hallmark of magnetically influenced plasma processes, shedding light on their magnetic field geometries and underlying emission mechanisms.

J0508-21 shows millijansky-level emission at 575–720 MHz with 20–50% circular polarization and periodic helicity reversals, suggesting a mix of persistent gyro-synchrotron emission and highly polarized auroral bursts, indicative of electron cyclotron maser processes.

On the other hand, for [BHB2007]-1, VLA data at 15 GHz has revealed 15–20% circular polarization linked to magnetic fields, alongside unpolarized emission likely caused by jet-induced shocks.

However, in both the cases, the results reveal diverse magnetic phenomena in young stars and underscore the need for coordinated multiwavelength studies to further understand their origins.

Local contact: Mario Dammasso