Modelling of variability of the chemically peculiar star phi Draconis

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Publikace nespadá pod Filozofickou fakultu, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
Název česky Modelování proměnnosti chemicky pekuliární hvězdy fí Draconis
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PRVÁK Milan LIŠKA Jiří KRTIČKA Jiří MIKULÁŠEK Zdeněk LUFTINGER Theresa

Rok publikování 2015
Druh Článek v odborném periodiku
Časopis / Zdroj ASTRONOMY & ASTROPHYSICS
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Doi http://dx.doi.org/10.1051/0004-6361/201526647
Obor Astronomie a nebeská mechanika, astrofyzika
Klíčová slova stars: chemically peculiar; stars: early-type; stars: variables: general; stars: individual: phi Dra
Popis Context. The presence of heavier chemical elements in stellar atmospheres influences the spectral energy distribution of stars. An uneven surface distribution of these elements, together with flux redistribution and stellar rotation, are commonly believed to be the primary causes of the variability of chemically peculiar (CP) stars. Aims. We aim to model the photometric variability of the CP star. Dra based on the assumption of inhomogeneous surface distribution of heavier elements and compare it to the observed variability of the star. We also intend to identify the processes that contribute most significantly to its photometric variability. Methods. We use a grid of TLUSTY model atmospheres and the SYNSPEC code to model the radiative flux emerging from the individual surface elements of. Dra with different chemical compositions. We integrate the emerging flux over the visible surface of the star at different phases throughout the entire rotational period to synthesise theoretical light curves of the star in several spectral bands. Results. The synthetic light curves in the visible and in the near-UV regions are in very good agreement with the observed variability of the star. The lack of usable far-UV measurements of the star precludes making any conclusions about the correctness of our model in this spectral region. We also obtained 194 new BVRI observations of phi Dra and improved its rotational period to P = 1.(d)716500(2). Conclusions. We show that the inhomogeneous distribution of elements, flux redistribution, and rotation of the star are fully capable of explaining the stellar variability in the visible and the near-UV regions. The flux redistribution is mainly caused by bound-free transitions of silicon and bound-bound transitions of iron.
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