- ID:
- ivo://CDS.VizieR/J/ApJ/703/L72
- Title:
- Hipparcos calibration of the TRGB
- Short Name:
- J/ApJ/703/L72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have detected the tip of the red giant branch (TRGB) in the solar neighborhood using near-infrared photometry from the Two Micron All Sky Survey (II/246) and DIRBE (J/ApJS/154/673) catalogs, and revised Hipparcos parallaxes. We confirm that the revised Hipparcos parallaxes are superior to the original ones, and that this improvement is necessary to detect the TRGB. We find a tip absolute magnitude of M_K_=-6.85+/-0.03, in agreement with that expected from previous tip measurements of the Large Magellanic Cloud, Small Magellanic Cloud, and Bulge. This represents the first geometric calibration of the TRGB and extends previous calibrations, based on metal-poor globular clusters, to solar metallicities. We attempted to use the TRGB to confirm the presence of the Lutz-Kelker bias, with inconclusive results. Attempts to detect the tip in the I band also produced inconsistent results, due to a lack of precise, homogeneous photometry for these bright stars.
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- 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/J/A+A/428/149
- Title:
- Hipparcos parallaxes of O stars
- Short Name:
- J/A+A/428/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the absolute visual magnitude of the majority of bright O stars in the sky as predicted from their spectral type with the absolute magnitude calculated from their apparent magnitude and the Hipparcos parallax. We find that many stars appear to be much fainter than expected, up to five magnitudes. We find no evidence for a correlation between magnitude differences and the stellar rotational velocity as suggested for OB stars by Lamers et al. (1997A&A...325L..25L), whose small sample of stars is partly included in ours.
1144. Hipparcos red stars
- ID:
- ivo://CDS.VizieR/J/A+A/397/997
- Title:
- Hipparcos red stars
- Short Name:
- J/A+A/397/997
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For Hipparcos M, S, and C spectral type stars, we provide calibrated instantaneous (epoch) Cousins V-I color indices using newly derived HpV_T2_ photometry. Three new sets of ground-based Cousins VI data have been obtained for more than 170 carbon and red M giants, observed at SAAO in 1984 and 1987 (table1), at Siding Spring Observatory in 2002 (table2), and with the Automatic Photoelectric Telescopes located at Fairborn Observatory from 1996 (table3). These datasets in combination with the published sources of VI photometry served to obtain the calibration curves linking Hipparcos/Tycho Hp-V_T2_ with the Cousins V-I index. In total, 321 carbon stars and 4464 M- and S-type stars have new V-I indices. The standard error of the mean V-I is about 0.1mag or better down to Hp~9 although it deteriorates rapidly at fainter magnitudes. These V-I indices can be used to verify the published Hipparcos V-I color indices. Thus, we have identified a handful of new cases where, instead of the real target, a random field star has been observed. A considerable fraction of the DMSA/C and DMSA/V solutions for red stars appear not to be warranted. Most likely such spurious solutions may originate from usage of a heavily biased color in the astrometric processing.
- ID:
- ivo://CDS.VizieR/J/AN/341/908
- Title:
- 308 Hipparcos stars EW Li and spectra
- Short Name:
- J/AN/341/908
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since early 2015 a spectroscopic monitoring campaign of selected Hipparcos stars is going on at the University Observatory Jena. The aim of this project is to search for lithium at 6708{AA}, which is a youth indicator, and to measure its equivalent width to identify young runaway stars in the sample (age<=50Myr) along with the Gaia data.
- 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/399/1167
- Title:
- Hipparcos Variability-Induced Movers
- Short Name:
- J/A+A/399/1167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hipparcos observations of some variable stars, and especially of long-period (e.g. Mira) variables, reveal a motion of the photocenter correlated with the brightness variation (variability-induced mover, VIM), suggesting the presence of a binary companion. A re-analysis of the Hipparcos photometric and astrometric data (Cat. <I/239>) does not confirm the VIM solution for 62 among the 288 VIM objects (21%) in the Hipparcos catalogue. Most of these 288 VIMs are long-period (e.g. Mira) variables (LPV). The effect of a revised chromaticity correction, which accounts for the color variations along the light cycle, was then investigated. It is based on "instantaneous" V-I color indices derived from Hipparcos and Tycho-2 (Cat. <I/259>) epoch photometry. Among the 188 LPVs flagged as VIM in the Hipparcos catalogue, 89 (47%) are not confirmed as VIM after this improved chromaticity correction is applied. This dramatic decrease in the number of VIM solutions is not surprising, since the chromaticity correction applied by the Hipparcos reduction consortia was based on a fixed V-I color. Astrophysical considerations lead us to adopt a more stringent criterion for accepting a VIM solution (first-kind risk of 0.27% instead of 10% as in the Hipparcos catalogue). With this more severe criterion, only 27 LPV stars remain VIM, thus rejecting 161 of the 188 (86%) of the LPVs defined as VIMs in the Hipparcos catalogue.
- 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)
- ID:
- ivo://CDS.VizieR/J/AJ/159/197
- Title:
- HIRES radial velocities of HD9446, HD43691 & HD179079
- Short Name:
- J/AJ/159/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transit Ephemeris Refinement and Monitoring Survey is a project that aims to detect transits of intermediate-long period planets by refining orbital parameters of the known radial velocity planets using additional data from ground-based telescopes, calculating a revised transit ephemeris for the planet, then monitoring the planet host star during the predicted transit window. Here we present the results from three systems that had high probabilities of transiting planets: HD9446b and c, HD43691b, and HD179079b. We provide new radial velocity (RV) measurements that are then used to improve the orbital solution for the known planets. We search the RV data for indications of additional planets in orbit and find that HD9446 shows a strong linear trend of 4.8{sigma}. Using the newly refined planet orbital solutions, which include a new best-fit solution for the orbital period of HD9446c, and an improved transit ephemerides, we found no evidence of transiting planets in the photometry for each system. Transits of HD9446b can be ruled out completely and transits HD9446c and HD43691b can be ruled out for impact parameters up to b=0.5778 and b=0.898, respectively, due to gaps in the photometry. A transit of HD179079b cannot be ruled out, however, due to the relatively small size of this planet compared to the large star and thus low signal to noise. We determine properties of the three host stars through spectroscopic analysis and find through photometric analysis that HD9446 exhibits periodic variability.
