Observations of Cepheids with the MOST satellite: contrast between pulsation modes

Autor(en)

N. R. Evans, R. Szabo, A. Derekas, László Szabados, C. Cameron, Werner Wolfgang Weiss

Abstrakt

The quantity and quality of satellite photometric data strings is revealing details in Cepheid variation at very low levels. Specifically, we observed a Cepheid pulsating in the fundamental mode and one pulsating in the first overtone with the Canadian MOST (Microvariability and Oscillations of Stars) satellite. The 3.7-d period fundamental mode pulsator (RT Aur) has a light curve that repeats precisely, and can be modelled by a Fourier series very accurately. The overtone pulsator (SZ Tau, 3.1 d period) on the other hand shows light-curve variation from cycle to cycle which we characterize by the variations in the Fourier parameters. We present arguments that we are seeing instability in the pulsation cycle of the overtone pulsator, and that this is also a characteristic of the O - C curves of overtone pulsators. On the other hand, deviations from cycle to cycle as a function of pulsation phase follow a similar pattern in both stars, increasing after minimum radius. In summary, pulsation in the overtone pulsator is less stable than that of the fundamental mode pulsator at both long and short time-scales.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Harvard-Smithsonian Center for Astrophysics, Hungarian Academy of Sciences, Cape Breton University

Journal

Monthly Notices of the Royal Astronomical Society

Band

446

Seiten

4008 - 4018

Anzahl der Seiten

11

ISSN

0035-8711

Publikationsdatum

02-2015

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/observations-of-cepheids-with-the-most-satellite-contrast-between-pulsation-modes(409e4207-29d5-465d-b4c6-507774ae79d2).html