Evidence for radio and X-ray auroral emissions from the magnetic B-type star rho OphA
| Authors | |
|---|---|
| Year of publication | 2020 |
| Type | Article in Periodical |
| Magazine / Source | Monthly Notices of the Royal Astronomical Society |
| MU Faculty or unit | |
| Citation | |
| Web | https://doi.org/10.1093/mnras/staa587 |
| Doi | http://dx.doi.org/10.1093/mnras/staa587 |
| Keywords | masers; stars: early-type; stars: individual: rho OphA; stars: magnetic field radio; continuum: stars; X-rays: stars |
| Description | We present new ATCA multiwavelength radio measurements (range 2.1-21.2 GHz) of the early-type magnetic star rho OphA, performed in 2019 March during three different observing sessions. These new ATCA observations evidence a clear rotational modulation of the stellar radio emission and the detection of coherent auroral radio emission from rho OphA at 2.1 GHz. We collected high-resolution optical spectra of rho OphA acquired by several instruments over a time span of about 10 yr. We also report new magnetic field measurements of rho OphA that, together with the radio light curves and the temporal variation of the equivalent width of the He I line (lambda = 5015 angstrom), were used to constrain the rotation period and the stellar magnetic field geometry. The above results have been used to model the stellar radio emission, modelling that allowed us to constrain the physical condition of rho OphA's magnetosphere. Past XMM-Newton measurements showed periodic X-ray pulses from. OphA. We correlate the X-ray light curve with themagnetic field geometry of rho OphA. The already published XMM-Newton data have been re-analysed showing that the X-ray spectra of rho OphA are compatible with the presence of a non-thermal X-ray component. We discuss a scenario where the emission phenomena occurring at the extremes of the electromagnetic spectrum, radio and X-ray, are directly induced by the same plasma process. We interpret the observed X-ray and radio features of rho OphA as having an auroral origin. |
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