Intrinsic linear polarization after the 2021 eruption of the recurrent nova RS Oph.
ATel #14863; Nikolov, Y. (Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences & IAFE/Conicet, Argentina), Luna, G. J. M. (IAFE/Conicet, Argentina)
on 15 Aug 2021; 03:27 UT
Credential Certification: Gerardo Juan Manuel Luna (gjmluna@iafe.uba.ar)
We report spectropolarimetric observations of the recurrent nova RS Oph obtained on
August 10, 2021 20:14 UT (~1.9 days after the reported discovery on August 8.93 UT by K. Geary, VSNET alert N.26131) with the 2-Channel-Focal-Reducer Rozhen (FoReRo2), attached
to the Cassegrain focus of the 2.0-m RCC telescope of the Bulgarian Rozhen National Astronomical Observatory.
Intrinsic linear polarization was detected. The intrinsic degree of linear polarization is 1% at a
position angle of 80 deg. The position angle is aligned with the highly collimated outflows detected during the past outburst in 2006 (e.g. Rupen et al. 2008, ApJ, 688, 559). Strong depolarization effects are well visible in H_alpha and He I 5876 emission lines. There is not an intrinsic component of linear polarization before the recurrent nova outburst (Nikolov, et al. 2019, Acta Astronomica, vol 69, no 4, p. 361-368). Variable linear polarization was observed during the 1985 outburst indicating the presence of intrinsic polarization (Cropper 1990). Cropper (1990) indicates that the intrinsic polarization developed during the outburst, and was not present at early times. Our spectropolarimetric observations before and after the 2021 outburst confirm this conclusion and suggest the early development of asymmetries in the outflow.
A figure can be found at: https://drive.google.com/file/d/1WUrJXKyRlNKdtwy8vITqd6wgry9bo6kO/view?usp=sharing
This work was supported by the Bulgarian Ministry of Education and Science under the National Research Programme Young scientists and postdoctoral students approved by DCM 577 / 17.08.2018 and by project number K$\Pi$-06-H28/2 08.12.2018, Bulgarian National Science Fund.
