- ID:
- ivo://CDS.VizieR/J/ApJS/252/3
- Title:
- High-velocity stars in the Gal. halo from LAMOST & Gaia
- Short Name:
- J/ApJS/252/3
- Date:
- 03 Mar 2022 11:59:54
- Publisher:
- CDS
- Description:
- In this paper, we report 591 high-velocity star candidates (HiVelSCs) selected from over 10 million spectra of Data Release 7 (DR7) of the Large Sky Area Multi-object Fiber Spectroscopic Telescope and the second Gaia data release, with three-dimensional velocities in the Galactic rest frame larger than 445km/s. We show that at least 43 HiVelSCs are unbound to the Galaxy with escape probabilities larger than 50%, and this number decreases to eight if the possible parallax zero-point error is corrected. Most of these HiVelSCs are metal-poor and slightly {alpha}-enhanced inner halo stars. Only 14% of them have [Fe/H]>-1, which may be the metal-rich "in situ" stars in the halo formed in the initial collapse of the Milky Way or metal-rich stars formed in the disk or bulge but kinematically heated. The low ratio of 14% implies that the bulk of the stellar halo was formed from the accretion and tidal disruption of satellite galaxies. In addition, HiVelSCs on retrograde orbits have slightly lower metallicities on average compared with those on prograde orbits; meanwhile, metal-poor HiVelSCs with [Fe/H]{<}-1 have an even faster mean retrograde velocity compared with metal-rich HiVelSCs. To investigate the origins of HiVelSCs, we perform orbit integrations and divide them into four types, i.e., hypervelocity stars, hyper-runaway stars, runaway stars and fast halo stars.
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- ID:
- ivo://CDS.VizieR/J/A+A/464/377
- Title:
- HIP binaries with radial velocities
- Short Name:
- J/A+A/464/377
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The comparison of the proper motions constructed from positions spanning a short (Hipparcos) or long time (Tycho-2) makes it possible to uncover binaries with periods of the order of or somewhat larger than the short time span (in this case, the 3 yr duration of the Hipparcos mission), since the unrecognised orbital motion will then add to the proper motion. A list of candidate proper motion binaries is constructed from a chi-square test evaluating the statistical significance of the difference between the Tycho-2 and Hipparcos proper motions for 103134 stars in common between the two catalogues (excluding components of visual systems). The present paper focuses on the evaluation of the detection efficiency of proper-motion binaries, using different kinds of control data (mostly radial velocities). The detection rate for entries from the Ninth Catalogue of Spectroscopic Binary Orbits (SB9) is evaluated, as well as for stars like barium stars, which are known to be all binaries, and finally for spectroscopic binaries identified from radial velocity data in the Geneva-Copenhagen survey of F and G dwarfs in the solar neighbourhood. Proper motion binaries are efficiently detected for systems with parallaxes in excess of 20mas, and periods in the range 1000-30000d. The shortest periods in this range (1000-2000d, i.e., once to twice the duration of the Hipparcos mission) may appear only as DMSA/G binaries (accelerated proper motion in the Hipparcos Double and Multiple System Annex). Proper motion binaries detected among SB9 systems having periods shorter than about 400d hint at triple systems, the proper-motion binary involving a component with a longer orbital period. A list of 19 candidate triple systems is provided. Binaries suspected of having low-mass (brown-dwarf-like) companions are listed as well. Among the 37 barium stars with parallaxes larger than 5mas, only 7 exhibit no evidence for duplicity whatsoever (be it spectroscopic or astrometric). Finally, the fraction of proper-motion binaries shows no significant variation among the various (regular) spectral classes, when due account is taken for the detection biases.
- ID:
- ivo://CDS.VizieR/J/A+AS/144/45
- Title:
- Hipparcos astrometry for 257 stars
- Short Name:
- J/A+AS/144/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present improved Hipparcos astrometry for 257 Hipparcos stars, resolved into 342 components. For 64 of the stars no astrometry was obtained in the Hipparcos Catalogue, while for the remaining stars additional components have been added by this solution or the positions have been revised considerably. We have used the published Hipparcos transit data for the new solutions, together with results from the second reduction of the Tycho data for defining better initial values.
- ID:
- ivo://CDS.VizieR/J/ApJS/254/42
- Title:
- Hipparcos-Gaia (EDR3) Catalog of Accelerations
- Short Name:
- J/ApJS/254/42
- Date:
- 28 Oct 2021 07:00:25
- Publisher:
- CDS
- Description:
- We present a cross-calibration of Hipparcos and Gaia EDR3 intended to identify astrometrically accelerating stars and to fit orbits to stars with faint, massive companions. The resulting catalog, the EDR3 edition of the Hipparcos-Gaia Catalog of Accelerations (HGCA), provides three proper motions with calibrated uncertainties on the EDR3 reference frame: the Hipparcos proper motion, the Gaia EDR3 proper motion, and the long-term proper motion given by the difference in position between Hipparcos and Gaia EDR3. Our approach is similar to that for the Gaia DR2 edition of the HGCA but offers a factor of ~3 improvement in precision thanks to the longer time baseline and improved data processing of Gaia EDR3. We again find that a 60/40 mixture of the two Hipparcos reductions outperforms either reduction individually, and we find strong evidence for locally variable frame rotations between all pairs of proper motion measurements. The substantial global frame rotation seen in DR2 proper motions has been removed in EDR3. We also correct for color- and magnitude-dependent frame rotations at a level of up to ~50{mu}as/yr in Gaia EDR3. We calibrate the Gaia EDR3 uncertainties using a sample of radial velocity standard stars without binary companions; we find an error inflation factor (a ratio of total to formal uncertainty) of 1.37. This is substantially lower than the position-dependent factor of ~1.7 found for Gaia DR2 and reflects the improved data processing in EDR3. While the catalog should be used with caution, its proper motion residuals provide a powerful tool to measure the masses and orbits of faint, massive companions to nearby stars.
- ID:
- ivo://CDS.VizieR/I/196
- Title:
- Hipparcos Input Catalogue, Version 2
- Short Name:
- I/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hipparcos Input Catalogue was constructed as the observing program for ESA's Hipparcos astrometry mission. This has resulted in a catalogue of stellar data including up-to-date information on positions, proper motions, magnitudes, colors, and when available, spectral types, radial velocities, multiplicity and variability information. The catalogue is complete to well-defined magnitude limits, and includes a substantial sampling of the most important stellar categories present in the solar neighbourhood beyond these limits. The magnitude limits vary from 7.3 to 9 magnitudes as a function of galactic latitude and spectral type, and there are no stars fainter than about V = 13 mag. 118000 stars are included in the Hipparcos Input Catalogue, about half of them have been selected within well-defined limits in V magnitude, spectral type and galactic latitude (the "survey"), half of them within proposed observing programs. The mean accuracies achieved, as demonstrated by comparison with the Hipparcos results (Turon et al. 1995A&A...304...82T) are 0.3 arcsec for the positions and 0.25 mag for the Hp magnitude, with accuracies of 0.02 mag or better for more than a third of the catalogue. The data set consists of the main catalogue, and the first supplement which contains more detailed information for multiple system components. Other supplements with identification charts can be found in the published version. A complete description is provided, either as a LaTeX file (intro.tex), or as a plain ascii file (intro.cat).
- ID:
- ivo://CDS.VizieR/J/A+AS/124/157
- Title:
- Hipparcos stars proper motions
- Short Name:
- J/A+AS/124/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absolute proper motions of 48 Hipparcos stars in nine fields distributed over the northern hemisphere are presented. The proper motions have been recently used as part of the Bonn program for the extragalactic link of the Hipparcos proper motion system. We describe methods which have led to the absolute proper motions of the major part of the Bonn fields for the link. For six fields the extragalactic calibration was achieved using the bright quasar in the centre of the field. In addition, data of three fields of globular clusters were included. For these fields the link to an extragalactic reference system was performed by stars, whose absolute proper motions with respect to galaxies were determined on plates of the Lick astrograph. In addition, we used for the link in one field plates from the ESO Schmidt telescope in combination with measurements from glass copies of the Palomar Sky Survey. The accuracy of a single proper motion is of the order of 2 to 3mas/a for each coordinate.
- ID:
- ivo://CDS.VizieR/I/311
- Title:
- Hipparcos, the New Reduction
- Short Name:
- I/311
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new reduction of the astrometric data as produced by the Hipparcos mission has been published, claiming accuracies for nearly all stars brighter than magnitude Hp=8 to be better, by up to a factor 4, than in the original catalogue. The new Hipparcos astrometric catalogue is checked for the quality of the data and the consistency of the formal errors as well as the possible presence of error correlations. The differences with the earlier publication are explained. Methods. The internal errors are followed through the reduction process, and the external errors are investigated on the basis of a comparison with radio observations of a small selection of stars, and the distribution of negative parallaxes. Error correlation levels are investigated and the reduction by more than a factor 10 as obtained in the new catalogue is explained. Results. The formal errors on the parallaxes for the new catalogue are confirmed. The presence of a small amount of additional noise, though unlikely, cannot be ruled out. Conclusions. The new reduction of the Hipparcos astrometric data provides an improvement by a factor 2.2 in the total weight compared to the catalogue published in 1997, and provides much improved data for a wide range of studies on stellar luminosities and local galactic kinematics.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A145
- Title:
- HIP stars DEC proper motions comparison
- Short Name:
- J/A+A/631/A145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The second solution of the Gaia catalog, which has been available since April 2018, plays an important role in the realization of the future Gaia reference frame. Since 1997, the reference frame has been materialized by the optical HIPPARCOS positions of about 120000 stars. The HIPPARCOS has been compared with and linked to the International Celestial Reference Frame (ICRF). The ICRF is materialized by means of the radio positions of extragalactic sources using very large baseline interferometry observations. Both, the HIPPARCOS and Gaia missions belong to the European Space Agency, and it is important to note that the Gaia catalog is going to replace the HIPPARCOS catalog. It has been shown that the International Latitude Service zenith telescope data pertaining to ground-based surveys that span a time baseline of about 80yr, and which are also key when measuring proper motions, could be useful for the accurate determination of {mu}_{delta}_ for 387 ILS stars. Therefore, in this study we aim first to reduce these stars to the HIPPARCOS reference system; second, to made our original catalog of {mu}_{delta}_, which we refer to as the ILS catalog, for these 387 bright stars; third, to present comparison results of the four catalogs by pairs (the ILS, HIPPARCOS or HIP, new HIPPARCOS or NHIP, and Gaia DR2); and fourth, to analyze the differences in {mu}_{delta}_ between pairs of catalogs to characterize the {mu}_{delta}_ errors for these catalogs with a special focus on the Gaia DR2 and ILS catalogs. At seven ILS sites around the world at latitude 39.1{deg}, a set of seven telescopes was used to monitor the latitude variation via observations of the same stars for about 80 yr. Here, the inverse task was applied to improve {mu}_{delta}_ values of the 387 HIPPARCOS stars using the previously mentioned observations. Due to the specific Horrebow-Talcott method of the measured star pair, it is difficult to determine {mu}_{delta}_ for each single star. However, we achieved this by developing the original method and in combination with the HIPPARCOS data. We used the previously developed least squares method and formula to determine the coefficients, which describe the systematic part of differences in {mu}_{delta}_ between the pairs of catalogs. We calculated the coefficients with the aforementioned formula (in line with the coordinates, stellar magnitude, and color index of every star) to compare ILS, HIP, NHIP, and Gaia DR2 data of {mu}_{delta}_ against each other by using the set of 387 stars. The presented differences of {mu}_{delta}_ show that the systematic errors in the four catalogs are nearly at the same level of 0.1mas/yr. This means that the DR2 and ILS {mu}_{delta}_ values are in good agreement with each other, and with values from the HIPPARCOS and new HIPPARCOS catalogs. Also, the random errors of differences are small ones; they are near 1mas/yr for ILS-HIP and ILS-NHIP, and about 2mas/yr for ILS-DR2, HIP-DR2, and NHIP-DR2. It is important to note that there is a similar level of proper motion formal errors in HIPPARCOS and new HIPPARCOS catalogs.
- ID:
- ivo://CDS.VizieR/J/BaltA/10/481
- Title:
- HIP visual binaries kinematics. I.
- Short Name:
- J/BaltA/10/481
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample consisting of 570 binary systems is compiled from several sources of visual binary stars with well-known orbital elements. High-precision trigonometric parallaxes (mean relative error about 5%) and proper motions (mean relative error about 3%) are extracted from the Hipparcos Catalogue or from the reprocessed Hipparcos data. However, 13% of the sample stars lack radial velocity measurements. Computed galactic velocity components and other kinematic parameters are used to divide the sample stars into kinematic age groups. The majority (89%) of the sample stars, with known radial velocities, are the thin disk stars, 9.5% binaries have thick disk kinematics and only 1.4% are halo stars. 85% of thin disk binaries are young or medium age stars and almost 15% are old thin disk stars. There is an urgent need to increase the number of the identified halo binary stars with known orbits and substantially improve the situation with their radial velocity data. Based on the data from the Hipparcos astrometry satellite (ESA)
- ID:
- ivo://CDS.VizieR/J/BaltA/11/153
- Title:
- HIP visual binaries kinematics. II.
- Short Name:
- J/BaltA/11/153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper continues kinematical investigation of the Hipparcos visual binaries with known orbits. A sample, consisting of 804 binary systems with orbital elements determined from ground-based observations, is selected. The mean relative error of their parallaxes is about 12% and the mean relative error of proper motions is about 4%. However, even 41% of the sample stars lack radial velocity measurements. The computed Galactic velocity components and other kinematical parameters are used to divide the stars with known radial velocities into kinematical age groups. The majority (92%) of binaries from the sample are thin disk stars, 7.6% have thick disk kinematics and only two binaries have halo kinematics. Among them, the long-period variable Mira Ceti has a very discordant Hipparcos and ground-based parallax values. From the whole sample, 60 stars are ascribed to the thick disk and halo population. There is an urgent need to increase the number of the identified halo binaries with known orbits and substantially improve the situation with radial velocity data for stars with known orbits. Based on the data from the Hipparcos astrometry satellite (ESA)
