Bulletin de la Société Royale des Sciences de Liège

0037-9565 1783-5720

 

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Sachindra Naik, Birendra Chhotaray & Neeraj Kumari

Optical Spectroscopy of 1A 0535+262 Before, During, and After the 2020 Giant X-ray Outburst

(Volume 93 - Année 2024 — No 2 - Proceeedings of the 3rd BINA Workshop on the Scientific Potential of the Indo-Belgian Cooperation)
DOI: 10.25518/0037-9565.11829
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Abstract

We present the findings from our study of the Be/X-ray binary 1A 0535+262/HD 245770 during the giant X-ray outburst in October 2020. We utilized the 1.2-m telescope at Mount Abu Infrared observatory for optical observations of the Be companion star. The outburst reached a peak X-ray flux of approximately 11 Crab in the 15-50 keV range, marking the highest ever recorded X-ray outburst from the pulsar. We conducted optical observations in the 6000-7200 Å range before, during, and after the X-ray outburst, aiming to examine the evolution of the circumstellar disc of the Be star from February 2020 to February 2022. Our optical spectra displayed prominent emission lines at 6563 Å (H I), 6678 Å (He I), and 7065 Å (He I). Notably, the Hα line exhibited significant variability in the spectra. Prior to and during the outburst, the line profiles appeared single-peaked, and asymmetric with broad red and blue wings, respectively. However, post-outburst observations revealed a double-peaked profile with asymmetry in the blue wing. Our pre-outburst observations confirmed a larger Be circumstellar disc that diminished in size as the outburst progressed. Additionally, the observed variations in the Hα line profile and parameters indicate the presence of a highly misaligned, precessing, and warped Be disc.

Keywords : Be–stars, neutron–stars, 1A 0535+262

Para citar este artículo

Sachindra Naik, Birendra Chhotaray & Neeraj Kumari, «Optical Spectroscopy of 1A 0535+262 Before, During, and After the 2020 Giant X-ray Outburst», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 93 - Année 2024, No 2 - Proceeedings of the 3rd BINA Workshop on the Scientific Potential of the Indo-Belgian Cooperation, 657-669 URL : https://popups.uliege.be/0037-9565/index.php?id=11829.

Acerca de: Sachindra Naik

Physical Research Laboratory, Navrangpura, Ahmedabad - 380009, India. Corresponding author: snaik@prl.res.in

Acerca de: Birendra Chhotaray

Physical Research Laboratory, Navrangpura, Ahmedabad - 380009, India and Indian Institute of Technology, Gandhinagar-382355, India

Acerca de: Neeraj Kumari

Physical Research Laboratory, Navrangpura, Ahmedabad - 380009, India