Light-curve and period changes of AB Andromedae

Derman, Ethem; Akalın, A; Selam, Salim O; Müyesseroğlu, Zekeriya; Demirçan, Osman

Light-curve and period changes of AB Andromedae

dc.contributor.author	Derman, Ethem
dc.contributor.author	Akalın, A
dc.contributor.author	Selam, Salim O
dc.contributor.author	Müyesseroğlu, Zekeriya
dc.contributor.author	Demirçan, Osman
dc.contributor.department	Fen Fakültesi	tr_TR
dc.date.accessioned	2020-02-17T08:49:05Z
dc.date.available	2020-02-17T08:49:05Z
dc.date.issued	1994
dc.description.abstract	New photoelectric observations of AB And obtained between 1989 and 1992 have been used, together with all available light curves from the literature, to study the light-curve variation of the system and its probable connection with the orbital period variation. A long-term brightness variation in the light levels is detected. The maximum brightness occurred in 1970 (±3 yr). A period study based on all available times of minimum light (of which 22 are newly determined) reveals that the photometric period of the system oscillates around a mean value (⁠P0≈0.331890d⁠) with an oscillation period of ≈88.0\textpm0.2 yr and a half-amplitude of 0.000 003 76 d. Such a variation can be caused by either (i) a period modulation due to the magnetic activity cycle of the active primary component, or (ii) a light-traveltime effect due to a third body in the system. It is shown that the third body, if it exists, can only be a white dwarf; this can be checked by ultraviolet spectroscopy. The rms light variation of the system predicted by Applegate's theory of the magnetic activity modulation of the orbital period is found to be comparable with the observed amplitude of long-term brightness variations of the system. However, the brightness variation is found to be 90° out of phase with the O–C curve. Such a phase shift can be explained in terms of the damping effect of the convective zone. The theory predicts a subsurface magnetic field of 7.4 kG for the primary component of AB And.
dc.description.index	Scopus
dc.description.index	Wos
dc.identifier.endpage	25	tr_TR
dc.identifier.issn/e-issn	0035-8711
dc.identifier.issn/e-issn	1365-2966
dc.identifier.issue	1	tr_TR
dc.identifier.startpage	19	tr_TR
dc.identifier.uri	https://doi.org/10.1093/mnras/267.1.19	tr_TR
dc.identifier.uri	http://hdl.handle.net/20.500.12575/69599
dc.identifier.volume	267	tr_TR
dc.language.iso	en	tr_TR
dc.relation.isversionof	10.1093/mnras/267.1.19	tr_TR
dc.relation.journal	Monthly Notices of the Royal Astronomical Society	tr_TR
dc.relation.publicationcategory	Makale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanı	tr_TR
dc.rights	CC0 1.0 Universal	*
dc.rights.uri	http://creativecommons.org/publicdomain/zero/1.0/	*
dc.subject	Binaries: Eclipsing	tr_TR
dc.title	Light-curve and period changes of AB Andromedae	tr_TR
dc.type	Article	tr_TR