The path to Z And-type outbursts: The case of V426 Sagittae (HBHA 1704-05)

Skopal, A.; Shugarov, S.Y.; Munari, U.; Masetti, N.; Marchesini, E.; Komžík, R.M.; Kundra, E.; Shagatova, N.; Tarasova, T.N.; Buil, C.; Boussin, C.; Shenavrin, V.I.; Hambsch, F.J.; Dallaporta, S.; Frigo, A.; Garde, O.; Zubareva, A.; Dubovský, P.A.; Kroll, P.

Авторы: Skopal A., Shugarov S.Yu, Munari U., Masetti N., Marchesini E., Komžík R.M., Kundra E., Shagatova N., Tarasova T.N., Buil C., Boussin C., Shenavrin V.I., Hambsch F.J., Dallaporta S., Frigo A., Garde O., Zubareva A., Dubovský P.A., Kroll P.
Журнал: Astronomy and Astrophysics
Том: 636
Год издания: 2020
Издательство: Springer Verlag
Местоположение издательства: Germany
Первая страница: A77, 1
Последняя страница: A77, 18
DOI: 10.1051/0004-6361/201937199
Аннотация: Context. The star V426 Sge (HBHA 1704-05), originally classified as an emission-line object and a semi-regular variable, brightenedat the beginning of August 2018, showing signatures of a symbiotic star outburst.Aims. We aim to confirm the nature of V426 Sge as a classical symbiotic star, determine the photometric ephemeris of the lightminima, and suggest the path from its 1968 symbiotic nova outburst to the following 2018 Z And-type outburst.Methods. We re-constructed an historical light curve (LC) of V426 Sge from approximately the year 1900, and used original low-(R ~ 500–1500; 330–880 nm) and high-resolution (R ~ 11 000–34 000; 360–760 nm) spectroscopy complemented with Swift-XRTand UVOT, optical UBVRCIC and near-infrared JHKL photometry obtained during the 2018 outburst and the following quiescence.Results. The historical LC reveals no symbiotic-like activity from ~1900 to 1967. In 1968, V426 Sge experienced a symbiotic novaoutburst that ceased around 1990. From approximately 1972, a wave-like orbitally related variation with a period of 493.4 +\- 0.7 daysdeveloped in the LC. This was interrupted by a Z And-type outburst from the beginning of August 2018 to the middle of February2019. At the maximum of the 2018 outburst, the burning white dwarf (WD) increased its temperature to > 2 x 105 K, generateda luminosity of ~7x10^37 (d=3.3 kpc)^2 erg s^-1 and blew a wind at the rate of ~3x 10^-6 M_sum yr^-1. Our spectral energy distributionmodels from the current quiescent phase reveal that the donor is a normal M4-5 III giant characterised with T_eff ~ 3400 K, RG ~ 106 (d/3.3 kpc) R_sun and LG_G ~ 1350 (d/3.3 kpc)^2 L_sun and the accretor is a low-mass ~0.5 M_sun WD.Conclusions. During the transition from the symbiotic nova outburst to the quiescent phase, a pronounced sinusoidal variation alongthe orbit develops in the LC of most symbiotic novae. The following eventual outburst is of Z And-type, when the accretion by theWD temporarily exceeds the upper limit of the stable burning. At this point the system becomes a classical symbiotic star.
Добавил в систему: Шугаров Сергей Юрьевич

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The path to Z And-type outbursts: The case of V426 Sagittae (HBHA 1704-05)статья

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