- ID:
- ivo://CDS.VizieR/J/ApJ/781/4
- Title:
- Photometry of high proper motion objects from WISE
- Short Name:
- J/ApJ/781/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I have used multi-epoch astrometry from the Wide-field Infrared Survey Explorer to perform a search for a distant companion to the Sun via its parallactic motion. I have not found an object of this kind down to W2=14.5. This limit corresponds to analogs of Saturn and Jupiter at 28000 and 82000AU, respectively, according to models of the Jovian planets by Fortney and coworkers. Models of brown dwarfs by Burrows and coworkers predict fainter fluxes at a given mass for the age of the solar system, producing a closer distance limit of 26000 AU for a Jupiter-mass brown dwarf. These constraints exclude most combinations of mass and separation at which a solar companion has been suggested to exist by various studies over the years.
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- ID:
- ivo://CDS.VizieR/J/A+A/620/A141
- Title:
- Physical properties of AM CVn stars
- Short Name:
- J/A+A/620/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AM CVn binaries are hydrogen deficient compact binaries with an orbital period in the 5-65min range and are predicted to be strong sources of persistent gravitational wave radiation. Using Gaia, Data Release 2, we present the parallaxes and proper motions of 41 out of the 56 known systems. Compared to the parallax determined using the HST, Fine Guidance Sensor we find that the archetype star, AM CVn, is significantly closer than previously thought. This resolves the high luminosity and mass accretion rate which models had difficulty in explaining. Using Pan-STARRS1 data we determine the absolute magnitude of the AM CVn stars. There is some evidence that donor stars have a higher mass and radius than expected for white dwarfs or that the donors are not white dwarfs. Using the distances to the known AM CVn stars we find strong evidence that a large population of AM CVn stars has yet to be discovered. As this value sets the background to the gravitational wave signal of LISA, this is of wide interest. We determine the mass transfer rate for 15 AM CVn stars and find that the majority has a rate significantly greater than expected from standard models. This is further evidence that the donor star has a greater size than expected.
- ID:
- ivo://CDS.VizieR/J/AJ/154/134
- Title:
- Planetary-mass brown dwarfs in the Taurus SFR
- Short Name:
- J/AJ/154/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the initial results from a survey for planetary-mass brown dwarfs in the Taurus star-forming region. We have identified brown dwarf candidates in Taurus using proper motions and photometry from several ground- and space- based facilities. Through spectroscopy of some of the more promising candidates, we have found 18 new members of Taurus. They have spectral types ranging from mid-M to early-L, and they include the four faintest known members in extinction-corrected K_s_, which should have masses as low as ~4-5 M_Jup_ according to evolutionary models. Two of the coolest new members (M9.25, M9.5) have mid-IR excesses that indicate the presence of disks. Two fainter objects with types of M9-L2 and M9-L3 also have red mid-IR colors relative to photospheres at =<L0, but since the photospheric colors are poorly defined at >L0, it is unclear whether they have excesses from disks. We also have obtained spectra of candidate members of the IC 348 and NGC 1333 clusters in Perseus that were identified by Luhman et al. Eight candidates are found to be probable members, three of which are among the faintest and least-massive known members of the clusters (~5 M_Jup_).
- ID:
- ivo://CDS.VizieR/J/A+A/563/A45
- Title:
- Pleiades cluster membership probabilities
- Short Name:
- J/A+A/563/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the advent of deep wide surveys, large photometric and astrometric catalogues of literally all nearby clusters and associations have been produced. The unprecedented accuracy and sensitivity of these data sets and their broad spatial, temporal and wavelength coverage make obsolete the classical membership selection methods that were based on a handful of colours and luminosities. We present a new technique designed to take full advantage of the high dimensionality (photometric, astrometric, temporal) of such a survey to derive self-consistent and robust membership probabilities of the Pleiades cluster. We aim at developing a methodology to infer membership probabilities to the Pleiades cluster from the DANCe multidimensional astro-photometric data set in a consistent way throughout the entire derivation. The determination of the membership probabilities has to be applicable to censored data and must incorporate the measurement uncertainties into the inference procedure. We use Bayes-theorem and a curvilinear forward model for the likelihood of the measurements of cluster members in the colour-magnitude space, to infer posterior membership probabilities. The distribution of the cluster members proper motions and the distribution of contaminants in the full multidimensional astro-photometric space is modelled with a mixture-of-Gaussians likelihood. We analyse several representation spaces composed of the proper motions plus a subset of the available magnitudes and colour indices. We select two prominent representation spaces composed of variables selected using feature relevance determination techniques based in Random Forests, and analyse the resulting samples of high probability candidates. We consistently find lists of high probability (p>0.9975) candidates with ~1000 sources, 4 to 5 times more than obtained in the most recent astro-photometric studies of the cluster. Multidimensional data sets require statistically sound multivariate analysis techniques to fully exploit their scientific information content. Proper motions in particular are, as expected, critical for the correct separation of contaminants. The methodology presented here is ready for application in data sets that include more dimensions, such as radial and/or rotational velocities, spectral indices, and variability.
- ID:
- ivo://CDS.VizieR/J/A+A/299/696
- Title:
- Pleiades field Membership probabilities
- Short Name:
- J/A+A/299/696
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of proper motions and photographic B,V magnitudes for stars up to B=19 mag within a region centered near Alcyone is presented. The catalogue is based on MAMA measurements of 8 plates taken with the Tautenburg Schmidt telescope. The survey includes ca. 14500 stars and covers a total field of about 9 square degrees. Membership probabilities, proper motions and B,V magnitudes are listed for 442 stars up to B=19 mag in the Pleiades field.
476. Pleiades member list
- ID:
- ivo://CDS.VizieR/J/A+A/332/575
- Title:
- Pleiades member list
- Short Name:
- J/A+A/332/575
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The luminosity function (LF) of the Pleiades cluster stars was constructed for the study of the LF fine structure related to pre-main sequence (MS) stellar evolution. Theoretical luminosity functions based on present-day pre-MS and MS stellar models were constructed and compared with observations. We tested both power- and log-normal laws describing the cluster star Initial Mass Function (IMF). Both single star formation burst- and age spread-models were examined. The agreement between the observed Pleiades colour-magnitude diagram with the new HIPPARCOS distance and the theoretical ZAMS for a normal metallicity is excellent when the model positions in the HR diagram are corrected to the helium abundance Y=0.34. The corresponding age of the cluster is logt=7.95. Three features (dips) were found in the observed cluster LF in a magnitude range M_V_=5-12mag. Two of them (at M_V_=7.5mag and 9.5mag) are assumed to be field LF features: Wielen and Kroupa dips. Theoretical models fail to reproduce them. We attributed the third (brightest) detail (the dip at M_V_=5.5mag) to the pre-MS evolution of Pleiades stars. The observed Pleiades LF corresponds in its brighter part to the standard Population I IMF. The log-normal IMF fits the observations much better than a simple power-law IMF. The brightest LF feature could be reproduced in the theoretical LF if a substantial age spread of order of several tens of Myrs is supposed to exist among the Pleiades stars.
- ID:
- ivo://CDS.VizieR/I/258
- Title:
- Pleiades positions and proper motions
- Short Name:
- I/258
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on a preliminary reference catalogue, combined with the catalogues PPM, ACRS and those in Eichhorn et al (1970, Cat. <I/90>), Jones (1973A&AS....9..313J) and Hertzsprung (1947AnLei..19a...1H), 33 exposures on 11 plates taken with the Zo-Se 40cm refractor (f=6895mm) in 86 years are reduced with the central overlapping technique, and high-precision positions and proper motions of 441 stars in the Pleiades astrometric standard region are obtained. The standard errors of star positions are less than +/-0.05arcsec, and the standard errors of proper motions for 90% stars in our reduction are less than +/-0.001arcsec/yr.
- ID:
- ivo://CDS.VizieR/I/300
- Title:
- PM2000 Bordeaux Proper Motion catalogue
- Short Name:
- I/300
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a proper motion catalogue of 2 670 974 stars, covering the declination zone +11{deg}<{delta}<+18{deg}. The catalogue has a limiting magnitude V=16.2 (Bordeaux CCD meridian circle magnitude) and is complete down to V=15.4. Depending on magnitude, the positional precision at mean epoch ranges from 50 to 70mas and the precision of proper motions varies from 1.5mas/yr to 6mas/yr. Meridian V magnitudes are provided for all objects together with additional photometry from the 2MASS catalogue when available (99.5% of objects). Positions and proper motions are on the ICRS (International Celestial Reference System). Proper motions are derived from the comparison of the positional M2000 catalogue (systematic observations of the Bordeaux Carte du Ciel Zone with the meridian circle, completed in 2000) with positions derived from the reduction of 512 Carte du Ciel plates of the Bordeaux zone (scanned at the APM Cambridge), the AC2000.2 catalogue, the USNO-A2.0 catalogue and the unpublished Yellow Sky (YS) USNO catalogue. Systematic offsets in 2MASS positions and in UCAC2 proper motions were revealed from comparisons with PM2000.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A1
- Title:
- Portrait Galactic disc
- Short Name:
- J/A+A/640/A1
- Date:
- 28 Feb 2022 08:13:18
- Publisher:
- CDS
- Description:
- The large astrometric and photometric survey performed by the Gaia mission allows for a panoptic view of the Galactic disc and in its stellar cluster population. Hundreds of clusters were only discovered after the latest Gaia data release (DR2) and have yet to be characterised. Here we make use of the deep and homogeneous Gaia photometry down to G=18 to estimate the distance, age, and interstellar reddening for about 2000 clusters identified with Gaia DR2 astrometry. We use these objects to study the structure and evolution of the Galactic disc. We rely on a set of objects with well-determined parameters in the literature to train an artificial neural network to estimate parameters from the Gaia photometry of cluster members and their mean parallax. We obtain reliable parameters for 1867 clusters. Our new homogeneous catalogue confirms the relative lack of old clusters in the inner disc (with a few notable exceptions). We also quantify and discuss the variation of scale height with cluster age, and detect the Galactic warp in the distribution of old clusters. This work results in a large and homogenous cluster catalogue. However, the present sample is still unable to trace the Outer spiral arm of the Milky Way, which indicates that the outer disc cluster census might still be incomplete.
- ID:
- ivo://CDS.VizieR/I/68A
- Title:
- Positions and Proper Motions in alpha Per cluster
- Short Name:
- I/68A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A list of positions and proper motions is given for 2027 stars of magnitude 7.5 to 12.5 within a radius of 3.5 deg. of alpha Persei. The values are poor for stars fainter than 11. The present list supersedes the microfiche edition (catalogue I/68/) which was described in the Bull. Inform. CDS 18, 81 (1980).
