Photometric studies of three multiperiodic ß Cephei stars: ß CMa, 15 CMa and KZ Mus

Autor(en)

R R Shobbrook, Gerald Handler, Denise Lorenz, D Mogorosi

Abstrakt

We have carried out single and multisite photometry of the three ß Cephei stars ß and 15 CMa as well as KZ Mus. For the two stars in CMa, we obtained 270 h of measurement in the Strošmgren uvy and Johnson V filters, while 150 h of time-resolved Strošmgren uvy photometry was acquired for KZ Mus. All three stars are multiperiodic variables, with three (ß CMa) and four (15 CMa, KZ Mus) independent pulsation modes. Two of the mode frequencies of 15 CMa are new discoveries and one of the known modes showed amplitude variations over the last 33 yr. Taken together, this fully explains the diverse behaviour of the star reported in the literature. Mode identification by means of the amplitude ratios in the different passbands suggests one radial mode for each star. In addition, ß CMa has a dominant mode while its third mode is non-radial with unknown l. The non-radial modes of 15 CMa, which are, form an almost equally split triplet that, if physical, would imply that we see the star under an inclination angle larger than 55°. The strongest non-radial mode of KZ Mus is, followed by the radial mode and a dipole mode. Its weakest known mode is non-radial with unknown l, confirming previous mode identifications for the pulsations of the star. The phased light curve for the strongest mode of 15 CMa has a descending branch steeper than the rising branch. A stillstand phenomenon during the rise to maximum light is indicated. Given the low photometric amplitude of this non-radial mode this is at first sight surprising, but it can be explained by the aspect angle of the mode. Œ 2006 RAS.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Australian National University, North-West University

Journal

Monthly Notices of the Royal Astronomical Society

Band

369

Seiten

171-181

Anzahl der Seiten

11

ISSN

0035-8711

Publikationsdatum

2006

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/166240a7-c48d-46c8-90e1-9887eddf8710