- ID:
- ivo://CDS.VizieR/J/A+A/650/A190
- Title:
- Wide companions to M and L subdwarfs
- Short Name:
- J/A+A/650/A190
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The aim of the project is to identify wide common proper motion companions to a sample of spectroscopically confirmed M and L metal-poor dwarfs (also known as subdwarfs) to investigate the impact of metallicity on the binary fraction of low-mass metal-poor binaries and to improve the determination of their metallicity from the higher-mass binary. We made use of Virtual Observatory tools and large-scale public surveys to look in Gaia for common proper motion companions to a well-defined sample of ultracool subdwarfs with spectral types later than M5 and metallicities below or equal to ~0.5dex. We collected low-resolution optical spectroscopy for our best system, which is a binary composed of one sdM1.5 subdwarf and one sdM5.5 subdwarf located at ~1360au, and for another two likely systems separated by more than 115000au. We confirm one wide companion to an M subdwarf, and infer a multiplicity for M subdwarfs (sdMs) of 1.0_-1.0_^+2.0^% for projected physical separations of up to 743000au. We also find four M-L systems, three of which are new detections. No colder companion was identified in any of the 219 M and L subdwarfs of the sample, mainly because of limitations on the detection of faint sources with Gaia. We infer a frequency of wide systems for sdM5-9.5 of 0.60_-0.60_^+1.17^% for projected physical separations larger than 1360au (up to 142400au). This study shows a multiplicity rate of 1.0_-1.0_^+2.0^% in sdMs, and 1.9_-1.9_^+3.7^% in extreme M subdwarfs. We did not find any companion for the ultra M subdwarfs of our sample, establishing an upper limit of 5.3% on binarity for these objects.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/2983
- Title:
- Wide low very low-mass binary systems
- Short Name:
- J/MNRAS/466/2983
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The frequency of multiple systems and their properties are key constraints of stellar formation and evolution. Formation mechanisms of very low-mass (VLM) objects are still under considerable debate, and an accurate assessment of their multiplicity and orbital properties is essential for constraining current theoretical models. Taking advantage of the virtual observatory capabilities, we looked for comoving low and VLM binary (or multiple) systems using the Large Area Survey of the UKIDSS LAS DR10, SDSS DR9 and the 2MASS Catalogues. Other catalogues (WISE, GLIMPSE, SuperCosmos, etc.) were used to derive the physical parameters of the systems. We report the identification of 36 low and VLM (~M0-L0 spectral types) candidates to binary/multiple system (separations between 200 and 92000au), whose physical association is confirmed through common proper motion, distance and low probability of chance alignment. This new system list notably increases the previous sampling in their mass-separation parameter space (~100). We have also found 50 low-mass objects that we can classify as ~L0-T2 according to their photometric information. Only one of these objects presents a common proper motion high-mass companion. Although we could not constrain the age of the majority of the candidates, probably most of them are still bound except four that may be under disruption processes. We suggest that our sample could be divided in two populations: one tightly bound wide VLM systems that are expected to last more than 10 Gyr, and other formed by weak bound wide VLM systems that will dissipate within a few Gyr.
- ID:
- ivo://CDS.VizieR/J/A+A/657/A53
- Title:
- Wide-orbit companions to K-type stars in Sco-Cen
- Short Name:
- J/A+A/657/A53
- Date:
- 17 Mar 2022 14:41:58
- Publisher:
- CDS
- Description:
- The detection of low-mass companions to stellar hosts is important for testing the formation scenarios of these systems. Companions at wide separations are particularly intriguing objects as they are easily accessible for variability studies of the rotational dynamics and cloud coverage of these brown dwarfs or planetary-mass objects. We aim to identify new low-mass companions to young stars using the astrometric measurements provided by the Gaia space mission. When possible, we use high-contrast imaging data collected with VLT/SPHERE. We identified companion candidates from a sample of K-type, pre-main-sequence stars in the Scorpius Centaurus association using the early version of the third data release of the Gaia space mission. Based on the provided positions, proper motions, and magnitudes, we identified all objects within a predefined radius, whose differential proper motions are consistent with a gravitationally bound system. As the ages of our systems are known, we derived companion masses through comparison with evolutionary tracks. For seven identified companion candidates we used additional data collected with VLT/SPHERE and VLT/NACO to assess the accuracy of the properties of the companions based on Gaia photometry alone. We identify 110 comoving companions that have a companionship likelihood of more than 95%. Further color-magnitude analysis confirms their Sco-Cen membership. We identify ten especially intriguing companions that have masses in the brown dwarf regime down to 20M_{Jup}_. Our high-contrast imaging data confirm both astrometry and photometric masses derived from Gaia alone. We discovered a new brown dwarf companion, TYC 8252-533-1 B, with a projected separation of approximately 570au from its Sun-like primary. It is likely to be located outside the debris disk around its primary star and SED modeling of Gaia, SPHERE, and NACO photometry provides a companion mass of 52^+17^_-11_M_{Jup}_. We show that the Gaia database can identify low-mass companions at wide separations from their host stars. For K-type Sco-Cen members, Gaia can detect sub-stellar objects at projected separations larger than 300au and with a sensitivity limit beyond 1000 and a lower mass limit down to 20M_{Jup}_. A similar analysis of other star-forming regions could significantly enlarge the sample size of such objects and facilitate testing of the formation and evolution theories of planetary systems.
- ID:
- ivo://CDS.VizieR/J/AJ/156/137
- Title:
- Wide-orbit Exoplanet search with IR Direct imaging
- Short Name:
- J/AJ/156/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results from the Wide-orbit Exoplanet search with InfraRed Direct imaging, or WEIRD, a survey designed to search for Jupiter-like companions on very wide orbits (1000-5000 au) around young stars (<120 Myr) that are known members of moving groups in the solar neighborhood (<70 pc). Companions that share the same age, distance, and metallicity as their host while being on large enough orbits to be studied as "isolated" objects make prime targets for spectroscopic observations, and they are valuable benchmark objects for exoplanet atmosphere models. The search strategy is based on deep imaging in multiple bands across the near-infrared domain. For all 177 objects of our sample, z'_ab_, J, [3.6], and [4.5] images were obtained with CFHT/MegaCam, GEMINI/GMOS, CFHT/WIRCam, GEMINI/Flamingos-2, and Spitzer/IRAC. Using this set of four images per target, we searched for sources with red z'_ab_ and [3.6]-[4.5] colors, typically reaching good completeness down to 2 M_Jup_ companions, while going down to 1 M_Jup_ for some targets, at separations of 1000-5000 au. The search yielded four candidate companions with the expected colors, but they were all rejected through follow-up proper motion observations. Our results constrain the occurrence of 1-13 M_Jup_ planetary-mass companions on orbits with a semimajor axis between 1000 and 5000 au at less than 0.03, with a 95% confidence level.
- ID:
- ivo://CDS.VizieR/J/other/PASA/24.118
- Title:
- Wide southern double stars
- Short Name:
- J/other/PASA/24.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Astrometric CCD observations have been made of wide (~3 to 60 arcsec) southern double stars selected from the Washington Double Star catalogue (WDS). Southern double stars have not been well studied in the past; typically they had not been measured since about 1930, and ~50% of them have been observed only once before our observations. Of the pairs measured ~80% show no evidence of motion since the last observation. This is Paper II in which we present the observations of 290 WDS stars in the approximate RA range 17h13m to 07h30m and in the declination range -70{deg} to -60{deg}. We suggest 412 companions for these 290 stars and list 29 (10%) pairs that have shown significant motion.
- ID:
- ivo://CDS.VizieR/J/AJ/136/312
- Title:
- 2001-2006 WIYN binary stars speckle observations
- Short Name:
- J/AJ/136/312
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A total of 1067 speckle observations of 345 binary stars are presented. Of these, 161 are double stars first resolved by Hipparcos, 17 are resolved for the first time in the observations presented here, and 21 are stars previously discovered by our program and reported in earlier papers in the series. In 947 cases, a magnitude difference is reported along with the relative astrometry.
- ID:
- ivo://CDS.VizieR/J/AJ/117/548
- Title:
- 1997 WIYN binary stars speckle observations
- Short Name:
- J/AJ/117/548
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two hundred seventy-seven position angle and separation measures of 154 double stars are presented. Three of the systems were previously unknown to be double, and 16 other systems were discovered earlier this decade by the Hipparcos satellite. Measures are derived from speckle observations taken with the Wisconsin-Indiana-Yale-NOAO (WIYN) 3.5 m telescope located at Kitt Peak, Arizona. Speckle images were obtained using two different imaging detectors, namely, a multianode microchannel array (MAMA) detector and a fast-readout CCD. A measurement precision study was performed on a sample of binaries with extremely well known orbits by comparing the measures obtained here to the ephemeris predictions. For the CCD, the root mean square (rms) deviation of residuals was found to be 3.5 milliarcseconds (mas) in separation and 12 in position angle, while the residuals of the MAMA data varied depending on the magnification used and seeing conditions but can be comparable or superior to the CCD values. In addition, the two cameras were compared in terms of the detection limit in total magnitude and magnitude difference of the systems under study. The MAMA system has the ability to detect some systems with magnitude differences larger than 3.5, although reliable astrometry could not be obtained on these objects. Reliable astrometry was obtained on a system of magnitude difference of 5.3 with the CCD system.
- ID:
- ivo://CDS.VizieR/J/AJ/139/205
- Title:
- 2007-2008 WIYN speckle observations of binaries
- Short Name:
- J/AJ/139/205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of 974 speckle observations of 546 binary stars are presented. Observations were obtained at the WIYN 3.5m Telescope at Kitt Peak National Observatory during the time interval from 2007 January to 2008 June. In all cases, the relative separation and position angle of the components are measured, and the magnitude difference is determined in 809 cases. The precision of the results as judged from repeat observations and objects with very well-determined orbits is similar to previous papers in this series, namely ~3mas in separation and <1{deg} in position angle in most cases. Similarly, the photometric precision remains consistent with previous WIYN speckle data, on average ~0.1mag per observation. Six systems of special interest are discussed.
- ID:
- ivo://CDS.VizieR/J/AJ/143/10
- Title:
- 2008-2009 WIYN speckle observations of binaries. VII.
- Short Name:
- J/AJ/143/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Five hundred thirty-one speckle measures of binary stars are reported. These data were taken mainly during the period 2008 June through 2009 October at the WIYN 3.5m Telescope at Kitt Peak and represent the last data set of single-filter speckle observations taken in the WIYN speckle program prior to the use of the current two-channel speckle camera. The astrometric and photometric precision of these observations is consistent with previous papers in this series: we obtain a typical linear measurement uncertainty of approximately 2.5mas, and the magnitude differences reported have typical uncertainties in the range of 0.1-0.14mag. In combination with measures already in the literature, the data presented here permit the revision of the orbit of A 1634AB (= HIP 76041) and the first determination of visual orbital elements for HDS 1895 (= HIP 65982).
- ID:
- ivo://CDS.VizieR/J/AJ/153/128
- Title:
- WOCS. LXXV. Hyades&Praesepe stellar lithium data
- Short Name:
- J/AJ/153/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- WIYN/Hydra spectroscopy (at R~15000) of the moderately metal-rich Praesepe and Hyades open clusters was used to study their main-sequence (MS) iron ([Fe/H]) and lithium (A(Li)) abundances. Self-consistent [Fe/H] and Li analyses of these clusters of consistent age, which we re-evaluate, confirms that they have consistent [Fe/H] and provides a foundation to investigate the poorly understood G-dwarf and F-dwarf Li-depletions. Neither phenomenon agrees with standard stellar evolution theory, but possible explanations abound. We supplement our A(Li) with previously published results placed on a uniform abundance scale. This creates the largest self-consistently analyzed sample of A(Li) in both the Hyades (90) and Praesepe (110). For each star, high-precision UBVRI photometry was used to determine a 10-color-based T_eff_ and then to test for photometric peculiarities indicated by a large {sigma}_Teff_ (>75 K). The stars that have large {sigma}_Teff_ were predominantly found to be binaries or stars with peculiar (apparent) A(Li). When considering only proper-motion members that have low {sigma}_Teff_ and are also photometrically consistent with the cluster MS fiducial, each cluster has a more tightly defined Li morphology than previously observed and the two clusters' A(Li) are indistinguishable. This suggests that clusters of consistent age and metallicity may have consistent Li-depletion trends across a broad range of T_eff_; no additional major parameters are required, at least for these two clusters. We propose that the combined Hyades and Praesepe data offer more rigorous constraints than does either cluster alone, and we discuss newly revealed features of the combined Li-T_eff_ trend.
