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HD 133880 is one of the six hot magnetic stars known to produce coherent pulsed radio emission by the process of electron cyclotron maser emission (ECME). In this paper, we present observations of ECME from this star over a wide frequency range, covering nearly 300 - 4000 MHz with the Giant Metrewave Radio Telescope (GMRT) and the Karl G. Jansky Very Large Array (VLA). This study, which is the first of its kind, has led to the discovery of several interesting characteristics of the phenomenon and also of the host star. We find that the observable properties of ECME pulses, e.g. the time lag between right and left circularly polarized pulses, the amplitudes of the pulses, and their upper cut-off frequencies appear to be dependent on the stellar orientation with respect to the line of sight. We suggest that all these phenomena, which are beyond the ideal picture, can be attributed to a highly azimuthally asymmetric matter distribution in the magnetosphere about the magnetic field axis, which is a consequence of both the high obliquity (the angle between rotation axis and the magnetic field axis) of the star and the deviation of the stellar magnetic field from a dipolar topology.
We present new radio/millimeter measurements of the hot magnetic star HR5907 obtained with the VLA and ALMA interferometers. We find that HR5907 is the most radio luminous early type star in the cm-mm band among those presently known. Its multi-wavel
HD 189733 is a K2 dwarf, orbited by a giant planet at 8.8 stellar radii. In order to study magnetospheric interactions between the star and the planet, we explore the large-scale magnetic field and activity of the host star. We collected spectra us
The non-thermal radio emission of main-sequence early-type stars is a signature of stellar magnetism. We present multi-wavelength (1.6-16.7 GHz) ATCA measurements of the early-type magnetic star rho OphC, which is a flat-spectrum non-thermal radio so
In this paper we simulate the cyclic circularly-polarised pulses of the ultra-cool dwarf TVLM513-46546, observed with the VLA at 4.88 and 8.44 GHz on May 2006, by using a 3D model of the auroral radio emission from the stellar magnetosphere. During t
In this paper we report 23 magnetic field measurements of the B3IV star HD 23478: 12 obtained from high resolution Stokes $V$ spectra using the ESPaDOnS (CFHT) and Narval (TBL) spectropolarimeters, and 11 from medium resolution Stokes $V$ spectra obt