ABSTRACT
Compact hierarchical triples (CHTs) are systems with the tertiary star orbiting the inner binary in an orbit shorter than 1000 d. CHT with an eclipsing binary as its inner binary can help us ...extract a multitude of information about all three stars in the system. In this study, we use independent observational techniques to estimate the orbital, stellar, and atmospheric parameters of two triple-lined CHT: BD+44 2258 and KIC 06525196. We find that the masses of stars in BD+44 2258 are $1.011\pm 0.029$, $0.941\pm 0.033$, and $0.907\pm 0.065 \, {\rm M}_{\odot }$ while in KIC 06525196 the estimated masses are $1.0351\pm 0.0055$, $0.9712\pm 0.0039 $, and $0.777\pm 0.012 \, {\rm M}_{\odot }$. Using spectral disentangling, we obtained individual spectra of all the stars and combined it with light-curve modelling to obtain radii, metallicities, and temperatures. Using stellar evolution models from mesa, we constrain the log(age) of BD+44 2258 to be 9.89 and 9.49 for KIC 06525196. Two stars in BD+44 2258 are found to be sub-giants while all three stars in KIC 06525196 are main-sequence stars. We constrain the mutual inclinations to certain angles for BD+44 2258 and KIC 06525196 using numerical integration. Integrating with tidal interaction schemes and stellar evolution models, we find that KIC 06525196 is a stable system. But the inner binary of BD+44 2258 merges within 550 Myr. The time of this merger is affected by the orientation of the tertiary, even rushing the collapse by ∼100 Myr when the mutual inclination is close to 90○.
ABSTRACT
Eclipse timing variations (ETVs) have been a successful tool for detecting circumbinary companions to eclipsing binaries (EBs). While TESS and Kepler have been prolific for ETV searches, ...they sometimes can be limited by time and sky coverage, a limitation that can be addressed by specialized ground-based ETV surveys. We present the initial results from the Solaris photometric survey, which uses four 0.5-m robotic telescopes in the Southern hemisphere to look for circumbinary companions. We present the method of light-curve extraction, detrending, and EB modelling using observations from the Solaris network. Using these light curves, we extract precise eclipse timings for seven EBs and look for companions using a Lomb–Scargle periodogram search. We find two possible periodic signals for the target GSC 08814–01026. With the system having strong activity, we check for the feasibility of orbital solutions at these two periods. We find that the 245 ± 1 d period is due to an M dwarf-mass companion. This makes GSC 08814–01026 a candidate compact hierarchical triple system. The other periodic signal at 146 ± 1 d is an artefact of stellar activity.
Abstract
We present the results of our spectroscopic observations of eight detached eclipsing binaries (DEBs), selected from the Kepler Eclipsing Binary Catalog. Radial velocities (RVs) were ...calculated from high-resolution spectra obtained with the HIgh-Dispersion Echelle Spectrograph (HIDES) spectrograph, attached to the 1.88-m telescope of the Okayama Astrophysical Observatory, and were used to characterize the targets in combination with the Kepler light curves. For each binary, we obtained a full set of orbital and physical parameters, reaching precision below 3 per cent in masses and radii for five pairs. By comparing our results with theoretical models, we assess the distance, age and evolutionary status of the researched objects. We also study eclipse timing variations of selected objects, and identify a new system with a γDor pulsator. Two systems are triples, and show lines coming from three components. In one case, the motion of the outer star and the perturbation in the RVs of the inner binary are clearly visible and periodical, which allows us to directly calculate the mass of the third star and inclination of the outer orbit. In the second case, we only see a clear motion of the tertiary and investigate two scenarios: that it is a linear trend coming from the orbital motion around the inner binary and that it is caused by a planetary mass companion. When possible, we also compare our results with the literature, and conclude that only by combining photometry with RVs, it is possible to obtain correct physical parameters of both components of a DEB.
ABSTRACT
We present results of the analysis of light and radial velocity (RV) curves of eight detached eclipsing binaries observed by the All-Sky Automated Survey, which we have followed up with ...high-resolution spectroscopy, and were later observed by the Keplersatellite as part of the K2mission. The RV measurements came from spectra obtained with OAO-188/HIDES, MPG-2.2 m/FEROS, SMARTS 1.5 m/CHIRON, Euler/CORALIE, ESO-3.6 m/HARPS, and OHP-1.93/ELODIE instruments. The K2 time-series photometry was analysed with the jktebop code, with out-of-eclipse modulations of different origin taken into account. Individual component spectra were retrieved with the fd3 code, and analysed with the code ispec in order to determine effective temperatures and metallicities. Absolute values of masses, radii, and other stellar parameters are calculated, as well as ages, found through isochrone fitting. For five systems, such analysis has been done for the first time. The presented sample consists of a variety of stars, from low-mass dwarfs, through G- and F-type main sequence objects, to evolved active sub-giants, one of which is found to be crossing the Hertzsprung gap. One target may contain a γ Dor-type pulsator, two more are parts of higher-order multiples, and spectra of their tertiaries were also retrieved and used to constrain the properties of these systems.
Aims. We aim to analyse KIC 4150611 (HD 181469) – an interesting, bright quintuple system that includes a hybrid δ Sct/γ Dor pulsator. Four periods of eclipses – 94.2, 8.65, 1.52 and 1.43 d – have ...been observed by the Kepler satellite, and three point sources (A, B, and C) are seen in high angular resolution images. Methods. From spectroscopic observations made with the HIDES spectrograph attached to the 1.88-m telescope of the Okayama Astrophysical Observatory (OAO), we have calculated for the first time radial velocities (RVs) of the component B – a pair of G-type stars – and combined them with Kepler photometry in order to obtain absolute physical parameters of this pair. We also managed to directly measure RVs of the pulsator, for the first time. Additionally, we modelled the light curves of the 1.52 and 1.43-day pairs, and measured their eclipse timing variations (ETVs). We also performed relative astrometry and photometry of three sources seen on the images taken with the NIRC2 camera of the Keck II telescope. Finally, we compared our results with theoretical isochrones. Results. The brightest component Aa is the hybrid pulsator, transited every 94.2 days by a pair of K/M-type stars (Ab1+Ab2), which themselves form a 1.52-day eclipsing binary. The components Ba and Bb are late G-type stars, forming another eclipsing pair with a 8.65 day period. Their masses and radii are MBa = 0.894 ± 0.010 M⊙, RBa = 0.802 ± 0.044 R⊙ for the primary, and MBb = 0.888 ± 0.010 M⊙, RBb = 0.856 ± 0.038 R⊙ for the secondary. The remaining period of 1.43 days is possibly related to a faint third star C, which itself is most likely a background object. The system’s properties are well-represented by a 35 Myr isochrone, basing on which the masses of the pulsator and the 1.52-day pair are MAa = 1.64(6) M⊙, and MAb,tot = 0.90(13) M⊙, respectively. There are also suggestions of additional bodies in the system.
ABSTRACT
We present the results of a spectroscopic campaign on eclipsing binaries with long orbital period (P = 20–75 d) carried out with the CHIRON spectrograph. Physical and orbital solutions for ...seven systems were derived from the V band, and I band ASAS, WASP, and TESS photometry, while radial velocities were calculated from high-quality optical spectra using a two-dimensional cross-correlation technique. The atmospheric parameters of the stars have been determined from the separated spectra. Most of our targets are composed of evolved stars (subgiants or red giants) but two systems show components in different phases of evolution and one possible merger. For four binaries, the masses and radii of the components were obtained with precision better than $3{{\ \rm per\ cent}}$. These objects provide very valuable information on stellar evolution.
ABSTRACT
We present a new analysis of the multiple-star V1200 Centauri based on the most recent observations for this system. We used the photometric observations from the Solaris network and the ...Transiting Exoplanet Survey Satellite telescope, combined with the new radial velocities from the CHIRON spectrograph and those published in the literature. We confirmed that V1200 Cen consists of a 2.5-d eclipsing binary orbited by a third body. We derived the parameters of the eclipsing components, which are $M_{\mathrm{ Aa}} = 1.393\pm 0.018\,$M⊙, $R_{\mathrm{ Aa}} = 1.407\pm 0.014\,$R⊙, and $T_{{\rm eff},\mathrm{ Aa}} = 6588\pm 58\,$K for the primary, and $M_{\mathrm{ Ab}} = 0.8633\pm 0.0081\,$M⊙, $R_{\mathrm{ Ab}} = 1.154\pm 0.014\,$R⊙, and $T_{{\rm eff},\mathrm{ Ab}} = 4475\pm 68\,$K for the secondary. Regarding the third body, we obtained significantly different results than those previously published. The period of the outer orbit is found to be 180.4 d, implying a minimum mass of $M_\mathrm{ B} = 0.871\pm 0.020\,$M⊙. Thus, we argue that V1200 Cen is a quadruple system with a secondary pair composed of two low-mass stars. Finally, we determined the ages of each eclipsing component using two evolution codes, namely mesa and cestam. We obtained ages of 16–18.5 and 5.5–7 Myr for the primary and the secondary, respectively. In particular, the secondary appears larger and hotter than that predicted at the age of the primary. We concluded that dynamical and tidal interactions occurring in multiples may alter the stellar properties and explain the apparent non-coevality of V1200 Centauri.
We report the discovery of a substellar-mass companion to the K0 giant HD 17092 with the Hobby-Eberly Telescope. In the absence of any correlation of the observed 360 day periodicity with the ...standard indicators of stellar activity, the observed radial velocity variations are most plausibly explained in terms of a Keplerian motion of a planetary-mass body around the star. As the esttmated stellar mass is 2.3 M unk, the minimum mass of the planet is 4.6 M sub(J). The planet's orbit is characterized by a mild eccentricity of e = 0.17 and a semimajor axis of 1.3 AU. This is the tenth published detection of a planetary companion around a red giant star. Such discoveries add to our understanding of planet formation around Intermediate-mass stars, and they provide dynamical information on the evolution of planetary systems around post-main-sequence stars.
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