- ID:
- ivo://CDS.VizieR/J/MNRAS/389/869
- Title:
- Multiplicity among bright stellar systems
- Short Name:
- J/MNRAS/389/869
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We consider the multiplicity of stellar systems with (combined) magnitude brighter than 6.00 in Hipparcos magnitudes. We identify 4559 such bright systems (including the Sun), and the frequencies of multiplicities 1, 2, ... , 7 are found to be 2718, 1437, 285, 86, 20, 11 and 2. We discuss the uncertainties, which are substantial. We also consider the distributions of periods of orbits and suborbits. We note that for even more restricted set of 478 systems with V_H_<=4.00 , the proportions of higher multiples up to sextuple are progressively larger (213, 179, 54, 19, 8, 5), suggesting substantial incompleteness in even the reasonably well studied larger sample.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/619/A81
- Title:
- Multiplicity among solar-type stars. IV.
- Short Name:
- J/A+A/619/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 261 K-type stars was observed with the spectrovelocimeter CORAVEL. The stars with a variable radial velocity were detected and the orbital elements of the spectroscopic binaries were derived.
- ID:
- ivo://CDS.VizieR/J/A+A/546/A10
- Title:
- Multiplicity in transiting planet-host stars
- Short Name:
- J/A+A/546/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the exoplanetary era, the Kepler spacecraft is causing a revolution by discovering thousands of new planet candidates. However, a follow-up program is needed to reject false candidates and fully characterize the bona-fide exoplanets. Our main aims are to 1./ detect and analyze close companions inside the typical Kepler point spread function (PSF) to study whether they are the responsible for the dimming found in Kepler light curves, 2./ study the change in the stellar and planetary parameters caused by an unresolved object, 3./ help validate the Kepler objects of interest (KOI) that do not have any object inside the Kepler PSF, and 4./ study the multiplicity rate of planet-host candidates. Such a large sample of observed planet-host candidates allows us to derive statistics for close (visual or bounded) companions to the harboring star.
- ID:
- ivo://CDS.VizieR/J/AJ/131/2986
- Title:
- Multiplicity of contact binaries
- Short Name:
- J/AJ/131/2986
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have attempted to establish observational evidence for the presence of distant companions that may have acquired and/or absorbed angular momentum during the evolution of multiple systems, thus facilitating or enabling the formation of contact binaries. In this preliminary investigation we use several techniques (some of them distance- independent) and mostly disregard the detection biases of individual techniques in an attempt to establish a lower limit to the frequency of triple systems. While the whole sample of 151 contact binary stars brighter than V_max_=10mag gives a firm lower limit of 42%{+/-}5%, the corresponding number for the much better observed northern-sky subsample is 59%{+/-}8%. These estimates indicate that most contact binary stars exist in multiple systems.
- ID:
- ivo://CDS.VizieR/J/AJ/154/184
- Title:
- Multiplicity of RV exoplanet host stars
- Short Name:
- J/AJ/154/184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Given the frequency of stellar multiplicity in the solar neighborhood, it is important to study the impacts this can have on exoplanet properties and orbital dynamics. There have been numerous imaging survey projects established to detect possible low-mass stellar companions to exoplanet host stars. Here, we provide the results from a systematic speckle imaging survey of known exoplanet host stars. In total, 71 stars were observed at 692 and 880 nm bands using the Differential Speckle Survey Instrument at the Gemini-north Observatory. Our results show that all but two of the stars included in this sample have no evidence of stellar companions with luminosities down to the detection and projected separation limits of our instrumentation. The mass-luminosity relationship is used to estimate the maximum mass a stellar companion can have without being detected. These results are used to discuss the potential for further radial velocity follow-up and interpretation of companion signals.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A73
- Title:
- Multiplicity study of transiting exoplanet hosts. I.
- Short Name:
- J/A+A/635/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many main-sequence stars are part of multiple systems. The effect of stellar multiplicity on planet formation and migration, however, is poorly understood. We study the multiplicity of stars hosting known transiting extra-solar planets to test competing theories on the formation mechanisms of hot Jupiters. We observed 45 exoplanet host stars using the infrared dual imaging spectrograph (IRDIS) of the Spectro-Polarimetric High-Contrast Exoplanet Research (SPHERE) instrument at the Very Large Telescope (VLT) to search for potential companions. For each identified candidate companion we determined the probability that it is gravitationally bound to its host by performing common proper motion checks and modelling of synthetic stellar populations around the host. In addition, we derived contrast limits as a function of angular separation to set upper limits on further companions in these systems. We converted the derived contrast into mass thresholds using AMES-Cond, AMES-Dusty, and BT-Settl models. We detected new candidate companions around K2-38, WASP-72, WASP-80, WASP-87, WASP-88, WASP-108, WASP-118, WASP-120, WASP-122, WASP123, WASP-130, WASP-131, and WASP-137. The closest candidates were detected at separations of 0.124"+/-0.007" and 0.189"+/-0.003" around WASP-108 and WASP-131; the measured K-band contrasts indicate that these are stellar companions of 0.35+/-0.02M_{sun}_ and 0.62^+0.05^_-0.04_M_{sun}_, respectively. Including the re-detection and confirmation of previously known companions in 13 other systems, we derived a multiplicity fraction of 55.4^+5.9^_-9.4_%. For the representative sub-sample of 40 hot Jupiter host stars among our targets, the derived multiplicity rate is 54.8^+6.3^_-9.9_%. Our data do not confirm any trend that systems with eccentric planetary companions are preferably part of multiple systems. On average, we reached a magnitude contrast of 8.5+/-0.9,mag at an angular separation of 0.5". This allows us to exclude additional stellar companions with masses higher than 0.08M_{sun}_ for almost all observed systems; around the closest and youngest systems, this sensitivity is achieved at physical separations as small as 10au. Our study shows that SPHERE is an ideal instrument for detecting and characterising close companions to exoplanetary host stars.Although the second data release of the Gaia mission also provides useful constraints for some of the systems, the achieved sensitivity provided by the current data release of this mission is not good enough to measure parallaxes and proper motions for all detected candidates. For 14 identified companion candidates further astrometric epochs are required to confirm their common proper motion at 5{sigma} significance.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A108
- Title:
- Multi-site obs. of WASP-12 b transit
- Short Name:
- J/A+A/551/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The transiting planet WASP-12 b was identified as a potential target for transit-timing studies because a departure from a linear ephemeris has been reported in the literature. Such deviations could be caused by an additional planet in the system. We attempt to confirm the claimed variations in transit timing and interpret their origin. We organised a multi-site campaign to observe transits by WASP-12 b in three observing seasons, using 0.5-2.6-metre telescopes. We obtained 61 transit light curves, many of them with sub-millimagnitude precision. The simultaneous analysis of the best-quality datasets allowed us to obtain refined system parameters, which agree with values reported in previous studies. The residuals versus a linear ephemeris reveal a possible periodic signal that may be approximated by a sinusoid with an amplitude of 0.00068+/-0.00013d and period of 500+/-20 orbital periods of WASP-12 b. The joint analysis of timing data and published radial velocity measurements results in a two-planet model that explains observations better than do single-planet scenarios. We hypothesise that WASP-12 b might not be the only planet in the system, and there might be the additional 0.1M_Jup_ body on a 3.6-d eccentric orbit. A dynamical analysis indicates that the proposed two-planet system is stable on long timescales.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A97
- Title:
- 0.8-6{mu}m calibrated spectrum of 55 Cnc
- Short Name:
- J/A+A/545/A97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ACME Spectra project provides absolutely calibrated, mostly empirical spectra of exoplanet host stars for use in analysis of the stars and their planets. Spectra are obtained from ground-based telescopes and are tied directly to calibrated ground- and space-based photometry. The spectra remain only "mostly" empirical because of telluric absorption, but interpolation of stellar models over the gaps in wavelength coverage provides continuous stellar spectra. Among other uses, the spectra are suitable for precisely converting observed secondary eclipses (occultations) into absolute flux units with minimal recourse to models. In this paper, I introduce ACME's methods and present a calibrated spectrum of the nearby, super-Earth hosting star 55 Cancri that spans the range from 0.81-5.05um.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A3
- Title:
- MUSE binaries in NGC 3201
- Short Name:
- J/A+A/632/A3
- Date:
- 09 Feb 2022 07:38:27
- Publisher:
- CDS
- Description:
- We utilize multi-epoch MUSE spectroscopy to study binaries in the core of NGC 3201. Our sample consists of 3553 stars with 54883 spectra in total comprising 3200 main-sequence stars up to 4 magnitudes below the turn-off. Each star in our sample has between 3 and 63 (with a median of 14) reliable radial velocity (RV) measurements within five years of observations. We introduce a statistical method to determine the probability of a star showing RV variations based on the whole inhomogeneous RV sample. Using HST photometry and an advanced dynamical MOCCA simulation of this specific GC we overcome observational biases that previous spectroscopic studies had to deal with. This allows us to infer a binary frequency in the MUSE FoV and enables us to deduce the underlying true binary frequency of (6.75+/-0.72)% in NGC 3201. The comparison of the MUSE observations with the MOCCA simulation suggests a significant fraction of primordial binaries. We can also confirm a radial increase of the binary fraction towards the GC centre due to mass segregation. We discovered that in our sample at least (57.5+/-7.9)% of blue straggler stars (BSS) are in a binary system. For the first time in a study of GCs, we were able to fit Keplerian orbits to a significant sample of 95 binaries. We present the binary system properties of eleven BSS and show evidence that two BSS formation scenarios, the mass transfer in binary (or triple) star systems and the coalescence due to binary-binary interactions, are present in our data. We also describe the binary and spectroscopic properties of four sub-subgiant (or red straggler) stars. Furthermore, we discovered two new black hole (BH) candidates with minimum masses (Msini) of (7.68+/-0.50)M_{sun}_, (4.4+/-2.8)M_{sun}_, and refine the minimum mass estimate on the already published BH to (4.53+/-0.21)M_{sun}_. These BHs are consistent with an extensive BH subsystem hosted by NGC 3201.
- ID:
- ivo://CDS.VizieR/J/ApJ/789/10
- Title:
- M33 WR and Of-type Stars
- Short Name:
- J/ApJ/789/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive star evolutionary models generally predict the correct ratio of WC-type and WN-type Wolf-Rayet stars at low metallicities, but underestimate the ratio at higher (solar and above) metallicities. One possible explanation for this failure is perhaps single-star models are not sufficient and Roche-lobe overflow in close binaries is necessary to produce the "extra" WC stars at higher metallicities. However, this would require the frequency of close massive binaries to be metallicity dependent. Here we test this hypothesis by searching for close Wolf-Rayet binaries in the high metallicity environments of M31 and the center of M33 as well as in the lower metallicity environments of the middle and outer regions of M33. After identifying ~100 Wolf-Rayet binaries based on radial velocity variations, we conclude that the close binary frequency of Wolf-Rayets is not metallicity dependent and thus other factors must be responsible for the overabundance of WC stars at high metallicities. However, our initial identifications and observations of these close binaries have already been put to good use as we are currently observing additional epochs for eventual orbit and mass determinations.
