- ID:
- ivo://CDS.VizieR/J/A+A/387/850
- Title:
- Radial velocities of eclipsing binaries
- Short Name:
- J/A+A/387/850
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic orbits of the 12 eclipsing binary systems, TW And, CD And, RS Ari, RU Cnc, TW Cnc, UU Cnc, V788 Cyg, AW Her, MM Her, RV Lib, EW Ori and ZZ UMa are obtained from Coravel and Elodie radial velocity measurements. We obtain a first orbit for CD And, RS Ari, TW Cnc, and V788 Cyg. For the systems TW And, RU Cnc, UU Cnc, AW Her, MM Her, RV Lib, EW Ori and ZZ UMa, the new spectroscopic orbits are either better or of quality comparable to that previously published. The physical properties of these systems were estimated with the photometric parameters from available data except CD And, TW Cnc, UU Cnc, V788 Cyg and RV Lib for which we found a model compatible with the observations. The systems RU Cnc, AW Her, MM Her and RV Lib belong to RS CVn group. In general these systems were difficult to observe with Coravel, on the one hand because the stars are relatively weak and on the other hand because of nature of the components giving peaks of correlation with weak contrast.
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- ID:
- ivo://CDS.VizieR/J/A+A/395/885
- Title:
- Radial velocities of HD 553
- Short Name:
- J/A+A/395/885
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 553 was discovered as an eclipsing binary by Hipparcos. Here, we present the first radial velocity curve for this system. It is found, that HD 553 is a double-lined spectroscopic binary. Despite the large luminosity difference, the two components of this system are of very similar mass. The primary, a K0-giant, fills a large fraction of its Roche-lobe. The secondary is, despite its very similar mass, still a late-type dwarf. The radial velocity curve allows to constrain several stellar and system parameters.
- ID:
- ivo://CDS.VizieR/J/AJ/154/216
- Title:
- Radial velocities of 41 Kepler eclipsing binaries
- Short Name:
- J/AJ/154/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eclipsing binaries are vital for directly determining stellar parameters without reliance on models or scaling relations. Spectroscopically derived parameters of detached and semi-detached binaries allow us to determine component masses that can inform theories of stellar and binary evolution. Here we present moderate resolution ground-based spectra of stars in close binary systems with and without (detected) tertiary companions observed by NASA's Kepler mission and analyzed for eclipse timing variations. We obtain radial velocities and spectroscopic orbits for five single-lined and 35 double-lined systems, and confirm one false positive eclipsing binary. For the double-lined spectroscopic binaries, we also determine individual component masses and examine the mass ratio M_2_/M_1_ distribution, which is dominated by binaries with like-mass pairs and semi-detached classical Algol systems that have undergone mass transfer. Finally, we constrain the mass of the tertiary component for five double-lined binaries with previously detected companions.
- ID:
- ivo://CDS.VizieR/J/A+A/576/A88
- Title:
- Radial velocities of 8 KOI eclipsing binaries
- Short Name:
- J/A+A/576/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler mission has searched for planetary transits in more than two hundred thousand stars by obtaining very accurate photometric data over a long period of time. Among the thousands of detected candidates, the planetary nature of around 15% has been established or validated by different techniques. But additional data are needed to characterize the rest of the candidates and reject other possible configurations. We started a follow-up program to validate, confirm, and characterize some of the planet candidates. In this paper we present the radial velocity analysis of those that present large variations, which are compatible with being eclipsing binaries. We also study those showing high rotational velocities, which prevents us from reaching the necessary precision to detect planetary-like objects. We present new radial velocity results for 13 Kepler objects of interest (KOIs) obtained with the CAFE spectrograph at the Calar Alto Observatory and analyze their high-spatial resolution (lucky) images obtained with AstraLux and the Kepler light curves of some interesting cases. We have found five spectroscopic and eclipsing binaries (group A). Among them, the case of KOI-3853 is of particular interest. This system is a new example of the so-called heartbeat stars, showing dynamic tidal distortions in the Kepler light curve. We have also detected duration and depth variations of the eclipse. We suggest possible scenarios to explain such an effect, including the presence of a third substellar body possibly detected in our radial velocity analysis. We also provide upper mass limits to the transiting companions of six other KOIs with high rotational velocities (group B). This property prevents the radial velocity method from achieving the necessary precision to detect planetary-like masses. Finally, we analyze the large radial velocity variations of two other KOIs, which are incompatible with the presence of planetary-mass objects (group C). These objects are likely to be stellar binaries. However, a longer timespan is needed to complete their characterization.
- ID:
- ivo://CDS.VizieR/J/A+A/413/293
- Title:
- Radial velocities of RZ Cas
- Short Name:
- J/A+A/413/293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a first report on the results of a multi-site campaign in 2001 of photometric and spectroscopic observations of the active semi-detached Algol-type system RZ Cas, we concentrate on the radial velocity (RV) variations. Using weak absorption lines we obtain an improved orbital solution for both components. In the orbital RV curve we observe a strong, asymmetric rotation effect. For the first time we detect rapid spectroscopic multi-mode pulsations in an Algol system. Whereas the photometrically observed oscillations were dominated by monoperiodic pulsations at frequency 64.19c/d until the year 2000, we find in 2001 a multiperiodic behaviour with two dominant frequencies of f1=56.600c/d and f2=64.189c/d. Both modes show amplitude variations over the orbital phase with a minimum at orbital phases phi=0.6-0.8 and a maximum just after the primary minimum (f2) and at phi=0.25 (f1). The different shape of amplitude modulation of the f1 and f2 modes points to different (l,m) mode structures. The modulation itself can be explained by assuming a variable extinction due to gas streams and an inhomogeneous accretion annulus that weakens the light from different regions of the primary depending on its orbital position.
- ID:
- ivo://CDS.VizieR/J/AJ/132/1539
- Title:
- Radial velocities of southern close binaries
- Short Name:
- J/AJ/132/1539
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for nine contact binaries: V1464 Aql, V759 Cen, DE Oct, MW Pav, BQ Phe, EL Aqr, SX Crv, VZ Lib, and GR Vir. For the first five of these, our observations are the first available radial velocity data. For the three remaining radial velocity variables, CE Hyi is a known visual binary, while CL Cet and V1084 Sco are suspected to be multiple systems in which the contact binary is spectrally dominated by its companion (which itself is a binary in V1084 Sco). Five additional variable stars, V872 Ara, BD Cap, HIP 69300, BX Ind, and V388 Pav, are of unknown type, but most are pulsating stars; we give their mean radial velocities and vsini.
- ID:
- ivo://CDS.VizieR/J/A+A/415/145
- Title:
- Radial velocities of 16 stars in NGC 6913
- Short Name:
- J/A+A/415/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between 1996 and 2003 we obtained 226 high resolution spectra of 16 stars in the field of the young open cluster NGC 6913, to constrain its main properties and study its internal kinematics. Twelve of the program stars turned out to be members, one of them probably unbound. Nine are binaries (one eclipsing and another double lined) and for seven of them the observations allowed us to derive the orbital elements. All but two of the nine discovered binaries are cluster members. In spite of the young age (a few Myr), the cluster already shows signs that could be interpreted as evidence of dynamical relaxation and mass segregation. However, they may be also the result of an unconventional formation scenario. The dynamical (virial) mass as estimated from the radial velocity dispersion is larger than the cluster luminous mass, which may be explained by a combination of the optically thick interstellar cloud that occults part of the cluster, the unbound state or undetected very wide binary orbit of some of the members that inflate the velocity dispersion and a high inclination for the axis of possible cluster angular momentum. All the discovered binaries are hard enough to survive average close encounters within the cluster and do not yet show signs of relaxation of the orbital elements to values typical of field binaries.
- ID:
- ivo://CDS.VizieR/J/ApJ/873/69
- Title:
- Radial velocities of the EB M-dwarf YYGem
- Short Name:
- J/ApJ/873/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- YY Gem is a short-period eclipsing binary system containing two nearly identical, rapidly rotating, very active early M dwarfs. This binary represents an important benchmark system for calibrating empirical relations between fundamental properties of low-mass stars and for testing theories of interior structure and evolution of these objects. Both components of YY Gem exhibit inflated radii, which has been attributed to poorly understood magnetic activity effects. Despite a long history of magnetic activity studies of this system, no direct magnetic field measurements have been made for it. Here we present a comprehensive characterization of the surface magnetic field in both components of YY Gem. We reconstructed the global field topologies with the help of a tomographic inversion technique applied to high-resolution spectropolarimetric data. This analysis revealed moderately complex global fields with a typical strength of 200-300G and anti-aligned dipolar components. A complementary Zeeman intensification analysis of the disentangled intensity spectra showed that the total mean field strength reaches 3.2-3.4kG in both components of YY Gem. We used these results together with other recent magnetic field measurements of M dwarfs to investigate the relation between the global and small-scale fields in these stars. We also assessed predictions of competing magnetoconvection interior structure models developed for YY Gem, finding that only one of them anticipated the surface field strength compatible with our observations. Results of our starspot mapping of YY Gem do not support the alternative family of theoretical stellar models, which attempts to explain the radius inflation by postulating a large spot filling factor.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/10
- Title:
- Radial velocities of the F-type EB* V2154 Cygni
- Short Name:
- J/ApJ/850/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report spectroscopic observations of the 2.63day, detached, F-type main-sequence eclipsing binary V2154 Cyg. We use our observations together with existing uvby photometric measurements to derive accurate absolute masses and radii for the stars that are good to better than 1.5%. We obtain masses of M1=1.269+/-0.017M_{sun}_ and M2=0.7542+/-0.0059M_{sun}_, radii of R1=1.477+/-0.012R_{sun}_ and R2=0.7232+/-0.0091R_{sun}_, and effective temperatures of 6770+/-150K and 5020+/-150K for the primary and secondary stars, respectively. Both components appear to have their rotations synchronized with the motion in the circular orbit. A comparison of the properties of the primary with current stellar evolution models gives good agreement for a metallicity of [Fe/H]=-0.17, which is consistent with photometric estimates, and an age of about 2.2Gyr. On the other hand, the K2 secondary is larger than predicted for its mass by about 4%. Similar discrepancies are known to exist for other cool stars, and are generally ascribed to stellar activity. The system is in fact an X-ray source, and we argue that the main site of the activity is the secondary star. Indirect estimates give a strength of about 1kG for the average surface magnetic field on that star. A previously known close visual companion to V2154 Cyg is shown to be physically bound, making the system a hierarchical triple.
- ID:
- ivo://CDS.VizieR/J/AJ/155/133
- Title:
- Radial velocities of the semi-detached Algol W UMi
- Short Name:
- J/AJ/155/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Double-lined eclipsing binaries allow accurate and direct determination of fundamental parameters such as mass and radius for each component, and they provide important constraints on the stellar structure and evolution models. In this study, we aim to determine a unique set of binary parameters for the Algol system W UMi and to examine its evolutionary status. New high-resolution time-series spectroscopic observations were carried out during 14 nights from 2008 April to 2011 March, and a total of 37 spectra were obtained using the Bohyunsan Optical Echelle Spectrograph. We measured the radial velocities (RVs) for both components, and the effective temperature of the primary star was found to be T_eff,1_=9310+/-90K by a comparison of the observed spectra and the Kurucz models. The physical parameters of W UMi were derived by an analysis of our RV data together with the multi-band light curves of Devinney et al. The individual masses, radii, and luminosities of both components are M1=3.68+/-0.10M_{sun}_ and M2=1.47+/-0.04M_{sun}_, R1=3.88+/-0.03R_{sun}_ and R2=3.13+/-0.03R_{sun}_, and L1=102+/-1L_{sun}_ and L2=7.3+/-0.1L_{sun}_, respectively. A comparison of these parameters with theoretical stellar models showed that the primary component lies in the main-sequence band, while the less massive secondary is noticeably evolved. The results indicate that the initially more massive star became the present secondary by losing most of its own mass via mass transfer to the companion (present primary).
