16 research outputs found
Photometric, Spectroscopic and Orbital Period Study of Three Early Type Semi-detached Systems: XZ Aql, UX Her and AT Peg
In this paper we present a combined photometric, spectroscopic and orbital
period study of three early-type eclipsing binary systems: XZ Aql, UX Her, and
AT Peg. As a result, we have derived the absolute parameters of their
components and, on that basis, we discuss their evolutionary states.
Furthermore, we compare their parameters with those of other binary systems and
with the theoretical models. An analysis of all available up-to-date times of
minima indicated that all three systems studied here show cyclic orbital
changes, their origin is discussed in detail. Finally, we performed a frequency
analysis for possible pulsational behavior and as a result we suggest that XZ
Aql hosts a {\delta} Scuti component.Comment: 40 pages, 16 figure
The Absolute Parameters of The Detached Eclipsing Binary V482 Per
We present the results of the spectroscopic, photometric and orbital period
variation analyses of the detached eclipsing binary \astrobj{V482~Per}. We
derived the absolute parameters of the system (M = 1.51 M,
M = 1.29 M, R = 2.39 R, R = 1.45
R, L = 10.15 L, L = 3.01 L) for the
first time in literature, based on an analysis of our own photometric and
spectroscopic observations. We confirm the nature of the variations observed in
the system's orbital period, suggested to be periodic by earlier works. A light
time effect due to a physically bound, star-sized companion (M = 2.14
M) on a highly eccentric (e = 0.83) orbit, seems to be the most
likely cause. We argue that the companion can not be a single star but another
binary instead. We calculated the evolutionary states of the system's
components, and we found that the primary is slightly evolving after the Main
Sequence, while the less massive secondary lies well inside it.Comment: Published in New Astronomy, Vol. 41, p. 42-4
The Algol System SZ Herculis: Physical Nature and Orbital Behavior
Multiband CCD photometric observations of SZ Her were obtained between 2008
February and May. The light curve was completely covered and indicated a
significant temperature difference between both components. The light-curve
synthesis presented in this paper indicates that the eclipsing binary is a
classical Algol-type system with parameters of =0.472, =87.57,
and (--)=2,381 K; the primary component fills
approximately 77% of its limiting lobe and is slightly larger than the
lobe-filling secondary. More than 1,100 times of minimum light spanning more
than one century were used to study an orbital behavior of the binary system.
It was found that the orbital period of SZ Her has varied due to a combination
of two periodic variations with cycle lengths of =85.8 yr and =42.5
yr and semi-amplitudes of =0.013 d and =0.007 d, respectively. The
most reasonable explanation for them is a pair of light-time effects (LITEs)
driven by the possible existence of two M-type companions with minimum masses
of =0.22 M and =0.19 M, that are located close to the
2:1 mean motion resonance. If two additional bodies exist, then the overall
dynamics of the multiple system may provide a significant clue to the formation
and evolution of the eclipsing pair.Comment: 23 pages, including 5 figures and 7 tables, accepted for publication
in A
Times of Minima of Some Eclipsing Binaries
We present new times of minima in the light curves of some eclipsing binarie
TOI-1431b/MASCARA-5b: a highly irradiated ultrahot Jupiter orbiting one of the hottest and brightest known exoplanet host stars
Stars and planetary system
The period variation of V839 Oph
In this study we present the results of the preliminary analysis of the period variation of V839 Oph based on the extensive series of minima times collected from the literature. The character of the (O-C) diagram can be approximated with a cyclic variation superimposed on a quadratic variation. The quadratic variation can be explained in terms of mass exchange/loss mechanism in the system, while the cyclic variation could be attributed to the light-time effect of a gravitationally bound third body to the system or the magnetic activity cycle of the primary component
First Chromospheric Activity and Doppler Imaging Study of PW And Using a New Doppler Imaging Code : SpotDIPy
Measuring the coverage of dark spots on cool stars is important to understanding how stellar magnetic activity scales with the rotation rate and convection zone depth. In this respect, it is crucial to infer surface magnetic patterns on G and K stars, to reveal solar-like stellar dynamos in action. Molecular bands serve as invaluable indicators of cool spots on the surfaces of stars, as they play a crucial role in enabling accurate assessments of the extent of spot coverage across the stellar surface. Therefore, more reliable surface images can be obtained considering the inversion of atomic lines with molecular bands. In this context, we simultaneously carry out Doppler imaging (DI) using atomic lines as well as titanium oxide band profiles of PW And (K2 V) and also investigate chromospheric activity indicators for the first time in the literature, using high-resolution spectra. The surface spot distribution obtained from the inversion process represents both atomic line and TiO-band profiles quite accurately. The chromospheric emission is also correlated with photospheric spot coverage, except during a possible flare event during the observations. We detect frequent flare activity, using TESS photometry. We also introduce a new open-source, Python-based DI code SpotDIPy that allows performing surface reconstructions of single stars using the maximum entropy method. We test the code by comparing surface reconstruction simulations with the extensively used DoTS code. We show that the surface brightness distribution maps reconstructed via both codes using the same simulated data are consistent with each other
How to Correctly Stitch Together Kepler Data of a Blazhko Star
One of the most challenging difficulties that precedes the frequency analysis of Kepler data for a Blazhko star is stitching together the data from different seasons (quarters). We discuss the preliminary steps in the stitching, detrending and rescaling process using the data for long-term Blazhko stars. We present the process on Kepler data of a Blazhko star with a variable Blazhko cycle and some first results of our analysis.status: publishe