scholarly journals TESS photometry of the eclipsing δ Scuti star AI Hydrae

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Jae Woo Lee ◽  
Kyeongsoo Hong ◽  
Martti H Kristiansen
Keyword(s):  
Binary Star ◽  
Primary Component ◽  
Secondary Component ◽  
Apsidal Motion ◽  
Star Model ◽  
Eclipsing Binary ◽  
Timing Diagram ◽  
Low Degree ◽  
Scuti Star ◽  
Good Agreement

Abstract AI Hya has been known as an eclipsing binary with a monoperiodic $\delta$ Sct pulsator. We present the results from its TESS (Transiting Exoplanet Survey Satellite) photometry observed during Sector 7. Including our five minimum epochs, the eclipse timing diagram displays the apsidal motion with a rate of $\dot{\omega } = 0.075 \pm 0.031\:$deg$\:$yr$^{-1}$, which corresponds to an apsidal period of $U = 4800\pm 2000\:$yr. The binary star model represents that the smaller, less massive primary component is $427\:$K hotter than the pulsating secondary, and our distance of $612\pm 36\:$pc is in good agreement with the Gaia distance of $644\pm 26\:$pc. We subtracted the binary effects from the observed TESS data and applied a multifrequency analysis to these residuals. The result reveals that AI Hya is multiperiodic in its pulsation. Of 14 signals detected, four ($f_1$, $f_2$, $f_3$, $f_6$) may be considered independent pulsation frequencies. The period ratios of $P_{\rm pul}/P_{\rm orb} = 0.012$–0.021 and the pulsation constants of $Q = 0.30$–0.52 d correspond to $\delta$ Sct pulsations in binaries. We found that the secondary component of AI Hya pulsates in both radial fundamental $F$ modes ($f_2$ and $f_3$) and non-radial $g_1$ modes with a low degree of $\ell = 2$ ($f_1$ and $f_6$).

scholarly journals Discovery and characterisation of long-period eclipsing binary stars from Kepler K2 campaigns 1, 2, and 3

2018 ◽  
Vol 616 ◽  
pp. A38 ◽  
Author(s):  
P. F. L. Maxted ◽  
R. J. Hutcheon
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Binary Star ◽  
Eclipsing Binaries ◽  
Star Model ◽  
Eclipsing Binary ◽  
Giant Stars ◽  
Long Period ◽  
Eclipsing Binary Stars

Context. The Kepler K2 mission now makes it possible to find and study a wider variety of eclipsing binary stars than has been possible to-date, particularly long-period systems with narrow eclipses. Aims. Our aim is to characterise eclipsing binary stars observed by the Kepler K2 mission with orbital periods longer than P ≈ 5.5 days. Methods. The ellc binary star model has been used to determine the geometry of eclipsing binary systems in Kepler K2 campaigns 1, 2 and 3. The nature of the stars in each binary is estimated by comparison to stellar evolution tracks in the effective temperature – mean stellar density plane. Results. 43 eclipsing binary systems have been identified and 40 of these are characterised in some detail. The majority of these systems are found to be late-type dwarf and sub-giant stars with masses in the range 0.6–1.4 solar masses. We identify two eclipsing binaries containing red giant stars, including one bright system with total eclipses that is ideal for detailed follow-up observations. The bright B3V-type star HD 142883 is found to be an eclipsing binary in a triple star system. We observe a series of frequencies at large multiples of the orbital frequency in BW Aqr that we tentatively identify as tidally induced pulsations in this well-studied eccentric binary system. We find that the faint eclipsing binary EPIC 201160323 shows rapid apsidal motion. Rotational modulation signals are observed in 13 eclipsing systems, the majority of which are found to rotate non-synchronously with their orbits. Conclusions. The K2 mission is a rich source of data that can be used to find long period eclipsing binary stars. These data combined with follow-up observations can be used to precisely measure the masses and radii of stars for which such fundamental data are currently lacking, e.g., sub-giant stars and slowly-rotating low-mass stars.

SX Piscium: A near-contact mass-transferring binary with a possible brown dwarf companion

2019 ◽  
Vol 71 (5) ◽  
Author(s):  
Zhi Hua Wang ◽  
Li Ying Zhu
Keyword(s):  
Binary Star ◽  
Mass Transfer Rate ◽  
Primary Component ◽  
Brown Dwarf ◽  
Precision Data ◽  
Eclipsing Binary ◽  
Short Period ◽  
Contact Mass ◽  
Photometric Monitoring ◽  
Mass Transfers

Abstract SX Psc is a short-period Algol-type eclipsing binary whose photometric analysis has long been ignored. Our photometric monitoring of this target covered from 2001 December to 2018 November. Aside from some curves observed at the primary eclipses, the complete four-color light curves in the BVRcIc band were also obtained. Photometric solutions were determined based on the Wilson–Devinney method. It is found that SX Psc is a semidetached binary where the inner Roche lobe of the secondary component has been filled. The filling factor for the primary is about 85% along with an inclination of ${89{^{\circ}_{.}}8}$, indicating that it is a near-contact total eclipsing binary system. Meanwhile, analysis of the O − C curve revealed that the orbital period is increasing continuously at a rate of dP/dt = 4.64(4) × 10−8 d yr−1. This is due to the mass transfers from the secondary to the primary component, which is in accord with the semidetached configuration of this binary star. With the assumption of conservative evolution, the mass transfer rate is estimated as $1.96\times 10^{-8}\, M_{\odot }$ yr−1. By deducting the long-term increasing trend in the O − C diagram, the high-precision data exhibits a cyclic variation, whereas it might be caused by the Applegate mechanism. Moreover, according to the light travel-time effect, there should be a candidate brown dwarf with a mass of no less than $m\,_3 = 0.067\, M_{\odot }$ orbiting the eclipsing binary. This is perhaps a unique case for an Algol-type binary accompanied by a substellar object.

scholarly journals Mode Determination by Fourier Analysis of Line-Profile Variations: Application to τ Peg

1993 ◽  
Vol 139 ◽  
pp. 147-147
Author(s):  
E.J. Kennelly ◽  
G.A.H. Walker ◽  
W.J. Merryfield ◽  
J.M. Matthews
Keyword(s):  
Time Series ◽  
High Resolution ◽  
Line Profiles ◽  
High Resolution Data ◽  
Low Degree ◽  
Scuti Star ◽  
High Degree ◽  
Scuti Stars ◽  
Resolution Data ◽  
Good Agreement

AbstractThe identification of modes of oscillation is an important first step towards the seismology of stars. Low- and high-degree nonradial modes of oscillation may appear as variations in the line profiles of rapidly rotating δ Scuti stars. We present a technique whereby complex patterns in the line profiles are decomposed into Fourier components in both time and “Doppler space”. The technique is applied to the 7.3-hour time series of high-resolution data obtained from CFHT for the δ Scuti star τ Peg. In addition to the low-degree mode which has been identified in photometric studies (Breger 1991), we find evidence for at least three high-degree modes near 11 and 15. Correcting for the rotation of the star, most of these modes appear to oscillate with frequencies near 17 cycles day-1. Our results are found to be in good agreement with the theoretical limits imposed on the frequencies of oscillation by the models of Dziembowski (1990).

scholarly journals KIC 7385478: An Eclipsing Binary with a γ Doradus Component

2017 ◽  
Vol 34 ◽  
Author(s):  
Orkun Özdarcan ◽  
Hasan Ali Dal
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
Spectroscopic Data ◽  
Primary Component ◽  
Secondary Component ◽  
Photometric Analysis ◽  
Eclipsing Binary ◽  
Cool Star ◽  
Star Activity ◽  
Dominant Period

AbstractWe present spectroscopic and photometric analysis of the eclipsing binary KIC 7385478. We find that the system is formed by F1V + K4III–IV components. Combining results from analysis of spectroscopic data and Kepler photometry, we calculate masses and radii of the primary and the secondary components as M1 = 1.71 ± 0.08 M⊙, M2 = 0.37 ± 0.04 M⊙ and R1 = 1.59 ± 0.03 R⊙, R2 = 1.90 ± 0.03 R⊙, respectively. Position of the primary component in HR diagram is in the region of γ Doradus type pulsators and residuals from light curve modelling exhibit additional light variation with a dominant period of ~ 0.5 d. These are clear evidences of the γ Doradus type pulsations on the primary component. We also observe occasional increase in amplitude of the residuals, where the orbital period becomes the most dominant period. These may be attributed to the cool star activity originating from the secondary component.

scholarly journals KIC 8553788: A pulsating Algol with an extreme mass ratio

2018 ◽  
Vol 616 ◽  
pp. A130 ◽  
Author(s):  
A. Liakos
Keyword(s):  
Radial Velocity ◽  
Spectral Type ◽  
Primary Component ◽  
Photometric Data ◽  
Light Curves ◽  
Secondary Component ◽  
Mass Ratio ◽  
Eclipsing Binary ◽  
Detached Binaries ◽  
Absolute Parameters

Context. The present research 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 photometric 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 δ Scuti stars-members of semi-detached binaries. Detailed light curves as well as 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. Aims. 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 a possible explanation for its extreme evolutionary status. Methods. Ground-based spectroscopic observations using the 2.3 m “Aristarchos” telescope were obtained and used for the estimation of the spectral type of the primary component and to model the light curves of the system with higher certainty. The short-cadence photometric data provided by the Kepler mission were analysed using standard eclipsing binary modelling techniques, while Fourier analysis was applied on their residuals aiming to reveal the properties of the intrinsic oscillations. The resulting photometric model was combined with a published radial velocity curve to obtain accurate absolute parameters for the components of the system. Results. The results show that the primary component of the system is of A8 spectral type, has a mass of 1.6 M⊙, and a radius of 2 R⊙. It is a relatively fast pulsator of δ Scuti type that oscillates in 89 frequency modes with the dominant one being 58.26 cycles day−1. On the other hand, the secondary component has a mass of only 0.07 M⊙, a radius of 1 R⊙, and a temperature of 4400 K. In addition, it was found to be magnetically active with migrating cool spots on its surface. Conclusions. KIC 8553788, according to its geometrical configuration and its pulsational properties, belongs to the group of 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 could therefore be considered as one of the most extreme cases.

Apsidal Motion Study of the Eclipsing Binary Star V459 Cas

2006 ◽  
Vol 305 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Ali Dariush ◽  
Moein Mosleh ◽  
Dena Dariush
Keyword(s):  
Binary Star ◽  
Apsidal Motion ◽  
Eclipsing Binary ◽  
Motion Study ◽  
Eclipsing Binary Star

scholarly journals KIC 4544587: An Eccentric, Short Period Binary with δ Scuti Pulsations and Tidally Excited Modes

2011 ◽  
Vol 7 (S282) ◽  
pp. 77-78
Author(s):  
Kelly Hambleton ◽  
Don Kurtz ◽  
Andrej Prša ◽  
Steven Bloemen ◽  
John Southworth
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
Main Sequence ◽  
Binary Star ◽  
Original Data ◽  
Primary Component ◽  
Apsidal Motion ◽  
Orbital Frequency ◽  
Short Period ◽  
Eclipsing Binary Star

AbstractKIC 4544587 is an eclipsing binary star with clear signs of apsidal motion and indications of tidal resonance. The primary component is an early A-type δ Scuti variable, with a temperature of 8270±250 K, whilst the secondary component is an early G-type main sequence star with a temperature of 6500±310 K. The orbital period of this system is 2.18911(1) d, with the light curve demonstrating a hump after secondary minimum due to distortion and reflection. The frequency spectrum of the residual data (the original data with the binary characteristics removed) contains both pressure (p) and gravity (g) modes. Eight of the g modes are precise multiples of the orbital frequency, to an accuracy greater than 3 σ. This is a signature of resonant excitation.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

Absolute Properties of the Eclipsing Binary Star RW Lacertae

2005 ◽  
Vol 130 (6) ◽  
pp. 2838-2846 ◽  
Author(s):  
Claud H. Sandberg Lacy ◽  
Guillermo Torres ◽  
Antonio Claret ◽  
Luiz Paulo Ribeiro Vaz
Keyword(s):  
Binary Star ◽  
Eclipsing Binary ◽  
Eclipsing Binary Star
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