Low-frequency GMRT observations of the magnetic Bp star HR Lup (HD 133880)

TL;DR

This study used GMRT radio observations at low frequencies to investigate the magnetic Bp star HR Lup, establishing upper limits on its emission and supporting a gyrosynchrotron emission model.

Contribution

First low-frequency GMRT observations of HR Lup, providing constraints that support the gyrosynchrotron emission mechanism for its radio emission.

Findings

No detection at 647 and 277 MHz, setting upper limits.

Supports optically thick gyrosynchrotron emission model.

No large emission enhancements observed.

Abstract

We present radio observations of the magnetic chemically peculiar Bp star HR Lup (HD 133880) at 647 and 277 MHz with the GMRT. At both frequencies the source is not detected but we are able to determine upper limits to the emission. The 647 MHz limits are particularly useful, with a 5\sigma\ value of 0.45 mJy. Also, no large enhancements of the emission were seen. The non-detections, along with previously published higher frequency detections, provide evidence that an optically thick gyrosynchrotron model is the correct mechanism for the radio emission of HR Lup.