- ID:
- ivo://CDS.VizieR/J/MNRAS/444/290
- Title:
- Star clusters distances and extinctions. II.
- Short Name:
- J/MNRAS/444/290
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Until now, it has been impossible to observationally measure how star cluster scaleheight evolves beyond 1Gyr as only small samples have been available. Here, we establish a novel method to determine the scaleheight of a cluster sample using modelled distributions and Kolmogorov-Smirnov tests. This allows us to determine the scaleheight with a 25% accuracy for samples of 38 clusters or more. We apply our method to investigate the temporal evolution of cluster scaleheight, using homogeneously selected sub-samples of Kharchenko et al. (MWSC, 2012, Cat. J/A+A/543/A156, 2013, J/A+A/558/A53 ), Dias et al. (DAML02, 2002A&A...389..871D, Cat. B/ocl), WEBDA, and Froebrich et al. (FSR, 2007MNRAS.374..399F, Cat. J/MNRAS/374/399). We identify a linear relationship between scaleheight and log(age/yr) of clusters, considerably different from field stars. The scaleheight increases from about 40pc at 1Myr to 75pc at 1Gyr, most likely due to internal evolution and external scattering events. After 1Gyr, there is a marked change of the behaviour, with the scaleheight linearly increasing with log(age/yr) to about 550pc at 3.5Gyr. The most likely interpretation is that the surviving clusters are only observable because they have been scattered away from the mid-plane in their past. A detailed understanding of this observational evidence can only be achieved with numerical simulations of the evolution of cluster samples in the Galactic disc. Furthermore, we find a weak trend of an age-independent increase in scaleheight with Galactocentric distance. There are no significant temporal or spatial variations of the cluster distribution zero-point. We determine the Sun's vertical displacement from the Galactic plane as Z_{sun}_=18.5+/-1.2pc.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/397/133
- Title:
- Star-forming complexes in the Galaxy
- Short Name:
- J/A+A/397/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a multiwavelength study of the plane of our Galaxy in order to establish a star-forming-complex catalogue which is as complete as possible. Features observed include H{alpha}, H109{alpha}, CO, the radio continuum and absorption lines. For each complex we have determined the position, the systemic velocity, the kinematic distance and, when possible, the stellar distance and the corresponding uncertainties. All of these parameters were determined as homogeneously as possible, in particular all the stellar distances have been (re)calculated with the same calibration and the kinematic distances with the same mean Galactic rotation curve. Through the complexes with stellar distance determination, a rotation curve has been fitted. It is in good agreement with the one of Brand & Blitz (1993, Cat. <J/A+A/275/67>).
- ID:
- ivo://CDS.VizieR/J/A+A/638/A76
- Title:
- StarHorse data for 5 surveys
- Short Name:
- J/A+A/638/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine high-resolution spectroscopic data from APOGEE-2 survey Data Release 16 (DR16) with broad-band photometric data from several sources, as well as parallaxes from Gaia Data Release 2 (DR2). Using the Bayesian isochrone-fitting code StarHorse, we derive distances, extinctions and astrophysical parameters for around 388,815 APOGEE stars, achieving typical distance uncertainties of 6% for APOGEE giants, 2% for APOGEE dwarfs, as well as extinction uncertainties of 0.07mag when all photometric information is available, and 0.17mag if optical photometry is missing. StarHorse uncertainties vary with the input spectroscopic catalogue, with the available photometry, and with the parallax uncertainties. To illustrate the impact of our results, we show that, thanks to Gaia DR2 and the now larger sky coverage of APOGEE-2 (including APOGEE-South), we obtain an extended map of the Galactic plane, providing an unprecedented coverage of the disk close to the Galactic mid-plane (|ZGal|<1kpc) from the Galactic Centre out to RGal 20 kpc. The improvements in statistics as well as distance and extinction uncertainties unveil the presence of the bar in stellar density, as well as the striking chemical duality in the innermost regions of the disk, now clearly extending to the inner bulge. We complement this paper with distances and extinctions for stars in other public released spectroscopic surveys: 324,999 in GALAH DR2, 4,928,715 in LAMOST DR5, 408,894 in RAVE DR6, and 6,095 in GES DR3.
- ID:
- ivo://CDS.VizieR/I/349
- Title:
- StarHorse, Gaia DR2 photo-astrometric distances
- Short Name:
- I/349
- Date:
- 05 Jan 2022
- Publisher:
- CDS
- Description:
- Combining the precise parallaxes and optical photometry delivered by Gaia's second data release with the photometric catalogues of Pan-STARRS1, 2MASS, and AllWISE, we derived Bayesian stellar parameters, distances, and extinctions for 265 million of the 285 million objects brighter than G=18. Because of the wide wavelength range used, our results substantially improve the accuracy and precision of previous extinction and effective temperature estimates. After cleaning our results for both unreliable input and output data, we retain 137 million stars, for which we achieve a median precision of 5% in distance, 0.20mag in V-band extinction, and 245K in effective temperature for G<=14, degrading towards fainter magnitudes (12%, 0.20mag, and 245K at G=16; 16%, 0.23mag, and 260K at G=17, respectively). We find a very good agreement with the asteroseismic surface gravities and distances of 7000 stars in the Kepler, K2-C3, and K2-C6 fields, with stellar parameters from the APOGEE survey, and with distances to star clusters. Our results are available through the ADQL query interface of the Gaia mirror at the Leibniz-Institut fuer Astrophysik Potsdam (gaia.aip.de) and as binary tables at data.aip.de. As a first application, we provide distance- and extinction-corrected colour-magnitude diagrams, extinction maps as a function of distance, and extensive density maps. These demonstrate the potential of our value-added dataset for mapping the three-dimensional structure of our Galaxy. In particular, we see a clear manifestation of the Galactic bar in the stellar density distributions, an observation that can almost be considered direct imaging of the Galactic bar.
- ID:
- ivo://CDS.VizieR/I/354
- Title:
- StarHorse2, Gaia EDR3 photo-astrometric distances
- Short Name:
- I/354
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present a catalogue of 362 million stellar parameters, distances, and extinctions derived from Gaia's Early Data Release (EDR3) cross-matched with the photometric catalogues of Pan-STARRS1, SkyMapper, 2MASS, and AllWISE. The higher precision of the Gaia EDR3 data, combined with the broad wavelength coverage of the additional photometric surveys and the new stellar-density priors of the StarHorse code, allows us to substantially improve the accuracy and precision over previous photo-astrometric stellarparameter estimates. At magnitude G=14 (17), our typical precisions amount to 3% (15%) in distance, 0.13mag (0.15mag) in V-band extinction, and 140K (180K) in effective temperature. Our results are validated by comparisons with open clusters, as well as with asteroseismic and spectroscopic measurements, indicating systematic errors smaller than the nominal uncertainties for the vast majority of objects. We also provide distance- and extinction-corrected colour-magnitude diagrams, extinction maps, and extensive stellar density maps that reveal detailed substructures in the Milky Way and beyond. The new density maps now probe a much greater volume, extending to regions beyond the Galactic bar and to Local Group galaxies, with a larger total number density. We publish our results through an ADQL query interface (gaia.aip.de) as well as via tables containing approximations of the full posterior distributions. Our multi-wavelength approach and the deep magnitude limit render our results useful also beyond the next Gaia release, DR3.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/106
- Title:
- Stellar and substellar members in Coma Berenices
- Short Name:
- J/ApJ/862/106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified stellar and substellar members in the nearby star cluster Coma Berenices, using photometry, proper motions, and distances of a combination of 2MASS, UKIDSS, URAT1, and Gaia/DR2 data. Those with Gaia/DR2 parallax measurements provide the most reliable sample to constrain the distance, averaging 86.7pc with a dispersion of 7.1pc, and age of ~800Myr, of the cluster. This age is older than the 400-600 Myr commonly adopted in the literature. Our analysis, complete within 5{deg} of the cluster radius, leads to identification of 192 candidates, among which, after field contamination is considered, about 148 are true members. The members have J~3mag to ~17.5mag, corresponding to stellar masses 2.3-0.06M_{sun}_. The mass function of the cluster peaks around 0.3M_{sun},_ and in the sense of dN/dm=m^-{alpha}^, where N is the number of members and m is stellar mass, with a slope {alpha}~=0.49+/-0.03 in the mass range 0.3-2.3M_{sun}_. This is much shallower than that of the field population in the solar neighborhood. The slope {alpha}=-1.69+/-0.14 from 0.3M_{sun}_ to 0.06M_{sun}_, the lowest mass in our sample. The cluster is mass-segregated and has a shape elongated toward the Galactic plane. Our list contains nine substellar members, including three new discoveries of an M8, an L1, and an L4 brown dwarfs, extending from the previously known coolest members of late-M types to even cooler types.
- ID:
- ivo://CDS.VizieR/J/ApJS/251/29
- Title:
- Stellar bow shock nebulae spectroscopic obs.
- Short Name:
- J/ApJS/251/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Arcuate mid-infrared nebulae known as stellar bow shock nebulae (SBNe) have been previously hypothesized to be supported by the strong stellar winds and/or luminosity of massive early-type stars. We present an optical spectroscopic survey of 84 stars identified from mid-infrared images as candidate SBN-supporting stars. Eighty-one of 84 sources, 96%, are O or early-B spectral types. K-band luminosities for a larger sample of 289 stars at the centers of bow shock nebulae are overwhelmingly consistent with OB stars. This affirms both that SBNe are supported by massive stars and that arcuate mid-infrared nebulae are reliable indicators of the presence of a massive star. The radial velocity dispersions of these systems and detections of double-lined systems indicate that at least 27 of the 74 systems with multiple observations (>36%) are candidate multiple-star systems. This rate is consistent with observed multiplicity rates of field OB stars detected with similar radial velocity surveys and lower than, but not inconsistent with, the multiplicity rates of OB stars in clusters and associations.
- ID:
- ivo://CDS.VizieR/J/ApJ/766/136
- Title:
- Stellar encounter rates in Galactic GCs
- Short Name:
- J/ApJ/766/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The high stellar densities in the cores of globular clusters cause significant stellar interactions. These stellar interactions can produce close binary mass-transferring systems involving compact objects and their progeny, such as X-ray binaries and radio millisecond pulsars. Comparing the numbers of these systems and interaction rates in different clusters drives our understanding of how cluster parameters affect the production of close binaries. In this paper we estimate stellar encounter rates ({Gamma}) for 124 Galactic globular clusters based on observational data as opposed to the methods previously employed, which assumed "King-model" profiles for all clusters. By deprojecting cluster surface brightness profiles to estimate luminosity density profiles, we treat "King-model" and "core-collapsed" clusters in the same way. In addition, we use Monte Carlo simulations to investigate the effects of uncertainties in various observational parameters (distance, reddening, surface brightness) on {Gamma}, producing the first catalog of globular cluster stellar encounter rates with estimated errors. Comparing our results with published observations of likely products of stellar interactions (numbers of X-ray binaries, numbers of radio millisecond pulsars, and {gamma}-ray luminosity) we find both clear correlations and some differences with published results.
- ID:
- ivo://CDS.VizieR/J/ApJS/254/20
- Title:
- Stellar groups in Taurus field from Gaia DR2 & LAMOST
- Short Name:
- J/ApJS/254/20
- Date:
- 17 Jan 2022 14:18:37
- Publisher:
- CDS
- Description:
- In this work, we present a systematic search for stellar groups in the Taurus field by applying the DBSCAN algorithm to the data from Gaia DR2. We find 22 groups, consisting of 8 young groups (Groups 1-8) at ages of 2-4Myr and distances of ~130-170pc, and 14 old groups (Groups 9-22) at ages of 8-49Myr and distances of ~110-210pc. We characterize the disk properties of group members and find 19 new disk-bearing stars, 8 of which are in the young groups with 11 others belonging to the comparatively old groups at the ages of 8-11Myr. We characterize the accretion properties of the group members with H{alpha} emission lines in their Large Sky Area Multi-Object Fibre Spectroscopic Telescope spectra, and discover one source in Group 10 at an age of 10Myr which still shows accretion activity. We investigate the kinematic relations among the old groups, find that Group 9 is kinematically related to the known Taurus members, and exclude any kinematic relations between Groups 10-22 and the known Taurus members.
- ID:
- ivo://CDS.VizieR/J/AJ/157/216
- Title:
- Stellar multiplicity rate of M dwarfs within 25 pc
- Short Name:
- J/AJ/157/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the largest, most comprehensive study ever done of the stellar multiplicity of the most common stars in the Galaxy, the red dwarfs. We have conducted an all-sky volume-limited survey for stellar companions to 1120 M dwarf primaries known to lie within 25 pc of the Sun via trigonometric parallaxes. In addition to a comprehensive literature search, stars were explored in new surveys for companions at separations of 2"-300". A reconnaissance of wide companions to separations of 300" was done via blinking archival images. I-band images were used to search our sample for companions at separations of 2"-180". Various astrometric and photometric methods were used to probe the inner 2" to reveal close companions. We report the discovery of 20 new companions and identify 56 candidate multiple systems. We find a stellar multiplicity rate of 26.8+/-1.4% and a stellar companion rate of 32.4+/-1.4% for M dwarfs. There is a broad peak in the separation distribution of the companions at 4-20 au, with a weak trend of smaller projected linear separations for lower mass primaries. A hint that M-dwarf multiplicity may be a function of tangential velocity is found, with faster moving, presumably older, stars found to be multiple somewhat less often. We calculate that stellar companions make up at least 17% of mass attributed to M dwarfs in the solar neighborhood, with roughly 11% of M-dwarf mass hidden as unresolved companions. Finally, when considering all M-dwarf primaries and companions, we find that the mass distribution for M dwarfs increases to the end of the stellar main sequence.
