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Optical spectroscopy of the Be/black hole binary MWC 656 - interaction of a black hole with a circumstellar disc

Zamanov, RK, Stoyanov, KA, Marchev, D, Tomov, NA, Wolter, U, Bode, MF, Nikolov, YM, Stefanov, SY, Kurtenkov, A and Latev, GY (2022) Optical spectroscopy of the Be/black hole binary MWC 656 - interaction of a black hole with a circumstellar disc. Astronomische Nachrichten, 343 (6-7). ISSN 0004-6337

Optical spectroscopy of th Beb black hole binary MWC 656 - interaction of a black hole with a circumstellar disc.pdf - Accepted Version

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We present new spectroscopic observations of the Be/black hole binary MWC 656 obtained during the period 2015–2021. We measure the equivalent width of Hα (EWα), Hβ ((Formula presented.)), and the distance between the peaks of Hα ((Formula presented.)), Hβ ((Formula presented.)), and FeII ((Formula presented.)) lines. Combining new and old data, we find that: (1) the density of the circumstellar disc of MWC 656 ((Formula presented.) versus (Formula presented.) diagram) is similar to the Be stars. For the Be stars, we find the relation (Formula presented.) km s−1, and the position of MWC 656 corresponds to the average behavior of the Be stars. This means that the presence of the black hole does not change the overall structure of the circumstellar disc; (2) the periodogram analysis indicates modulation of (Formula presented.) with a period (Formula presented.) days, which is identical to the binary orbital period. The maxima of (Formula presented.) and (Formula presented.) are around periastron (phase zero); (3) around orbital phase zero, (Formula presented.) and (Formula presented.) decrease by about (Formula presented.) km s−1. This suggests that we observe an increase of the circumstellar disc size induced by the periastron passage of the black hole and that the entire circumstellar disc pulsates with the orbital period with relative amplitude of 10–20%. The observations also indicate, that the reason for the black hole in MWC 656 to be in deep quiescence is a very low efficiency of accretion ((Formula presented.)).

Item Type: Article
Additional Information: This is the peer reviewed version of the following article: Zamanov, R. K., Stoyanov, K. A., Marchev, D., et al. 2022, Astron. Nachr., 343, e20224019., which has been published in final form at https://doi.org/10.1002/asna.20224019. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.
Uncontrolled Keywords: 0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Wiley
SWORD Depositor: A Symplectic
Date Deposited: 07 Nov 2022 15:25
Last Modified: 19 Jul 2023 00:50
DOI or ID number: 10.1002/asna.20224019
URI: https://researchonline.ljmu.ac.uk/id/eprint/18052
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