41 research outputs found
Asteroseismology of Kepler Algol type oscillating eclipsing binaries
Context. This research paper contains light curve modelling, spectroscopy and
detailed asteroseismic studies for four out of five in total semidetached
eclipsing binaries with a delta Scuti component, that have been detected to
date through Kepler mission, namely KIC 06669809, KIC 10581918, KIC 10619109
and KIC 11175495.
Aims. The goal is to study the pulsational characteristics of the oscillating
stars of the systems as well as to estimate their absolute parameters and
enrich the so far poor sample of this kind of systems.
Methods. Ground based spectroscopic observations provide the means to
estimate the spectral types of the primary components and to model the light
curves with higher certainty. The photometric data are analysed using eclipsing
binary modeling techniques, while Fourier analysis is applied on their
residuals in order to reveal the pulsation frequency modes.
Results. The results of analyses show that the primaries are pulsating stars
of delta Scuti type and that all systems belong to the group of Algol type
binaries with an oscillating star, namely oEA stars. The primaries of KIC
06669809, KIC 10581918, and KIC 10619109 pulsate in three, two, and five
frequencies, respectively and in more than 200 other detected as combinations.
The delta Scuti star of KIC 11175495 is the youngest and the fastest pulsator
in binary systems that has ever been found and it oscillates in three main non
radial frequencies, while other 153 are also found as depended ones. Moreover,
a comparison of their properties with other systems of the same type as well as
with theoretical models of pulsating stars are also presented and discussed.Comment: 22 pages, 29 figures, accepted for publication in A&
KIC 8553788: A pulsating Algol with an extreme mass ratio
The present paper focuses on the eclipsing binary KIC 8553788 which belongs
to two different types of binary systems regarding its physical properties. In
particular, it is one of the 71 oscillating stars of Algol type that have been
discovered so far and one of the six that have been published based on high
cadence data of the Kepler mission. In addition, it is one of the four
semi-detached binaries of the group of R CMa type systems, while its pulsating
component has the fourth fastest frequency among the delta Scuti stars-members
of semi-detached binaries. Detailed light curves, spectroscopic and pulsation
analyses are presented, while possible explanation scenarios for the evolution
of the system involving past mass transfer, mass loss and/or angular momentum
loss due to the presence of a tertiary component are discussed. The goal of the
study is to extract the pulsational characteristics of the oscillating star of
the system, to estimate the absolute parameters of its components and to
provide possible explanation for its extreme evolutionary status. The results
show that the primary component of the system is of A8 spectral type, has a
mass of 1.6 M_sun, and a radius of 2 R_sun. It is a relatively fast pulsator
that oscillates in 89 frequency modes with the dominant one to be 58.26 c/d.
The secondary component has a mass of only 0.07 M_sun, a radius of 1 R_sun, and
a temperature of 4400 K. KIC 8553788 according to its geometrical configuration
and its pulsational properties belongs to the group of the oscillating stars of
Algol type, while according to its very low mass ratio and its relatively short
orbital period belongs also to the group of R CMa stars. If confirmed by radial
velocity data of the secondary component, the system would have the lowest mass
ratio that has ever been found in semi-detached systems and it can be
considered as one of the most extreme cases.Comment: 13 pages, 17 figures. Accepted for publication in Astronomy &
Astrophysic