Multicolor Photometry and Peculiarities of the Spectrum for the post-AGB Candidate AU Vulpeculae (IRAS 20160+2734)

Ikonnikova, N.P.; Shenavrin, V.I.; Komissarova, G.V.; Burlak, M.A.; Shaposhnikov, I.A.; Belinskii, A.A.; Esipov, V.F.; Tatarnikov, A.M.; Dodin, A.V.; Zheltoukhov, S.G.

Авторы: Ikonnikova N.P., Shenavrin V.I., Komissarova G.V., Burlak M.A., Shaposhnikov I.A., Belinskii A.A., Esipov V.F., Tatarnikov A.M., Dodin A.V., Zheltoukhov S.G.
Журнал: Astronomy Letters
Том: 47
Номер: 7
Год издания: 2021
Издательство: Maik Nauka/Interperiodica Publishing
Местоположение издательства: Russian Federation
Первая страница: 485
Последняя страница: 504
DOI: 10.1134/S1063773721070057
Аннотация: We present the results of a photometric monitoring in the UBV RcIc and JHKLM bands over 2016–2020, low-resolution spectroscopy, and an analysis of the data from the ASAS-3 and ASASSNphotometric surveys for the semiregular variable AU Vul (IRAS 20160+2734), a post-AGB candidate.The star is shown to experience quasi-periodic brightness oscillations with variable amplitude and periods 67–75 and 145–150 days in different time intervals. The star is classified by its spectrum at maximum light as an early G supergiant. In this spectrum, Hα, Hβ, and higher terms of the Balmer series are weakened, possibly, because of emission components, while the absorptions of s-process elements (Ba II, Sr II, and Y II) are slightly strengthened. An Hα emission has been detected in the spectrum on the ascending branch of the light curve. TiO absorption bands with a maximum intensity at minimum light are observed in the spectra at different brightness levels. The spectral energy distribution in the range 0.44 (B)–2.2 (K) μm corresponds to spectral types from G2I at maximum to G8I at minimum light. An emission excess has been detected in the L and M bands. The spectral energy distribution in the range 0.44–90 μmconstructed from our own observations andWISE, MSX, IRAS, and AKARI data is satisfactorily described by the sum of three components: a star and dust envelopes with T_hot = 1000 K and T_cold = 150 K. Using the distance based on the Gaia EDR3 parallax, D ≈ 2300 pc, we have estimated the absolute magnitude, M_V ≈ −4.45 mag, and the luminosity, L ≈ 5450L_sun. A comparison with evolutionary models has shown that AU Vul may be at the very beginning of the post-AGB stage of evolution and have amass ∼ 0.55M_sun. We note that the star has a number of properties that distinguish it from typical post-AGB objects and make it akin to RV Tau stars.
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Multicolor Photometry and Peculiarities of the Spectrum for the post-AGB Candidate AU Vulpeculae (IRAS 20160+2734)статья

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