Open AccessA first‐overtone RR Lyrae star with cyclic period changes
Author(s) -
Derekas A.,
Kiss L. L.,
Udalski A.,
Bedding T. R.,
Szatmáry K.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08242.x
Subject(s) - physics , light curve , rr lyrae variable , astrophysics , overtone , large magellanic cloud , amplitude , star (game theory) , modulation (music) , period (music) , astronomy , variable star , stars , spectral line , optics , globular cluster , acoustics
A detailed light‐curve analysis is presented for a first‐overtone RR Lyrae star, MACHO* J050918.712−695015.31, based on MACHO and OGLE‐III observations. As a foreground object of the Large Magellanic Cloud, it gives an extraordinary opportunity to study an almost continuous, 12‐yr long data set of a relatively bright ( V ≈ 15.0 mag) RRc star with rapid period change. Cyclic period modulation is suggested by the O–C method, where the cycle length is about 8 yr. With the available unique data set, we could draw strong limits on other light‐curve changes that may be associated with the period modulation. We could exclude both multiple periodicity and amplitude modulation unambiguously. Any theoretical model should reproduce the observed lack of photometric modulations. Simple arguments are also given for possible hydromagnetic effects.