- ID:
- ivo://CDS.VizieR/J/A+A/630/A150
- Title:
- Astrometric data for 211 GAPN sample
- Short Name:
- J/A+A/630/A150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have compiled a catalogue of central stars of planetary nebulae (CSPN) with reliable distances and positions obtained from Gaia Data Release 2 (DR2) astrometry. Distances derived from parallaxes allow us to analyse the galactic distribution and estimate other parameters such as sizes, kinematical ages, bolometric magnitudes, and luminosities. Our objective is to analyse the information regarding distances together with other available literature data about photometric properties, nebular kinematics, and stellar effective temperatures to throw new light on this rapid and rather unknown evolutionary phase. We seek to understand how Gaia distances compare with other indirect methods commonly used and, in particular, with those derived from non-local thermodynamic equilibrium (non-LTE) models; how many planetary nebulae (PNe) populate the Galaxy; and how are they spatially distributed. We also aim to comprehend their intrinsic luminosities, range of physical sizes of the nebulae; how to derive the values for their kinematical ages; and whether those ages are compatible with those derived from evolutionary models. We considered all PNe listed in catalogues from different authors and in Hong Kong/AAO/Strasbourg/H{alpha} (HASH) database. By X-matching their positions with Gaia DR2 astrometry we were able to identify 1571 objects in Gaia second archive, for which we assumed distances calculated upon a Bayesian statistical approach. From those objects, we selected a sample of PNe with good quality parallax measurements and distance derivations, we which refer to as our Golden Astrometry PNe sample (GAPN), and obtained literature values of their apparent sizes, radial and expansion velocities, visual magnitudes, interstellar reddening, and effective temperatures. We found that the distances derived from DR2 parallaxes compare well with previous astrometric derivations of the United States Naval Observatory and Hubble Space Telescope, but that distances inferred from non-LTE model fitting are overestimated and need to be carefully reviewed. From literature apparent sizes, we calculated the physical radii for a subsample of nebulae that we used to derive the so-called kinematical ages, taking into account literature expansion velocities. Luminosities calculated with DR2 distances were combined with literature central stars Teff values in a Hertzsprung-Russell (HR) diagram to infer information on the evolutionary status of the nebulae. We compared their positions with updated evolutionary tracks finding a rather consistent picture. Stars with the smallest associated nebular radii are located in the flat luminosity region of the HR diagram, while those with the largest radii correspond to objects in a later stage, getting dimmer on their way to become a white dwarf. Finally, we commented on the completeness of our catalogue and calculated an approximate value for the total number of PNe in the Galaxy.
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- ID:
- ivo://CDS.VizieR/J/AJ/131/1784
- Title:
- Astrometric Grid Giant Star Survey. I.
- Short Name:
- J/AJ/131/1784
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a campaign of multiple-epoch echelle spectroscopy of relatively faint (V=9.5-13.5mag) red giants observed as potential astrometric grid stars for the Space Interferometry Mission (SIM PlanetQuest). Data are analyzed for 775 stars selected from the Grid Giant Star Survey, spanning a wide range of effective temperatures (Teff), gravities, and metallicities. The spectra are used to determine these stellar parameters and to monitor radial velocity (RV) variability at the 100m/s level.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1911
- Title:
- Astrometric Grid Giant Star Survey. III.
- Short Name:
- J/AJ/140/1911
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of high-resolution (~55000) spectral observations of 830 photometrically pre-selected candidate red giants in the magnitude range of V=9-12. We develop a pipeline for automated determination of the stellar atmospheric parameters from these spectra and estimate Teff, logg, [Fe/H], microturbulence velocity, and projected rotational velocities, vsin i, for the stars. The analysis confirms that the candidate selection procedure yielded red giants with very high success rate. We show that most of these stars are G and K giants with slightly subsolar metallicity ([Fe/H]~-0.3dex). An analysis of Mg abundances in the sample results in consistency of the [Mg/Fe] vs [Fe/H] trend with published results.
- ID:
- ivo://CDS.VizieR/J/AJ/160/141
- Title:
- Astrometric measurements of * bet LMi
- Short Name:
- J/AJ/160/141
- Date:
- 09 Mar 2022
- Publisher:
- CDS
- Description:
- bet LMi is a double-lined visual binary with an orbital period of ~39yr. Via a simultaneous fitting to both astrometric and radial velocity measurements, we give a complete and improved orbit solution with high precision. Then, the component masses are precisely determined as 2.98{+/-}0.10M{sun} and 1.92{+/-}0.04M{sun} with a relative precision of ~3%, respectively. The orbital parallax is determined to be 19.6{+/-}0.2mas, which is two times more precise than Hipparcos parallax. With the known apparent magnitudes and magnitude difference of the components, we derive the luminosity of the components as 50.7{+/-}1.8L{sun} and 9.1{+/-}4.1L{sun}. The estimated radii of the components are 9.4{+/-}0.3R{sun} and 3.7{+/-}1.5R{sun}.
- ID:
- ivo://CDS.VizieR/J/ApJ/757/29
- Title:
- Astrometric measurements of HD 143275
- Short Name:
- J/ApJ/757/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The highly eccentric Be binary system {delta} Sco reached periastron during early 2011 July, when the distance between the primary and secondary was a few times the size of the primary disk in the H band. This opened a window of opportunity to study how the gaseous disks around Be stars respond to gravitational disturbance. We first refine the binary parameters with the best orbital phase coverage data from the Navy Precision Optical Interferometer. Then we present the first imaging results of the disk after the periastron, based on seven nights of five telescope observations with the MIRC combiner at the CHARA array. We found that the disk was inclined 27{deg}.6+/-6{deg}.0 from the plane of the sky, had a half-light radius of 0.49mas (2.2 stellar radii), and consistently contributed 71.4%+/-2.7% of the total flux in the H band from night to night, suggesting no ongoing transfer of material into the disk during the periastron. The new estimation of the periastron passage is UT 2011 July 3 07:00+/-4:30. Re-analysis of archival VLTI-AMBER interferometry data allowed us to determine the rotation direction of the primary disk, constraining it to be inclined either ~119{deg} or ~171{deg} relative to the orbital plane of the binary system. We also detect inner disk asymmetries that could be explained by spot-like emission with a few percent of the disk total flux moving in Keplerian orbits, although we lack sufficient angular resolution to be sure of this interpretation and cannot yet rule out spiral density waves or other more complicated geometries.
- ID:
- ivo://CDS.VizieR/J/ApJS/231/15
- Title:
- Astrometric monitoring of ultracool dwarf binaries
- Short Name:
- J/ApJS/231/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the full results of our decade-long astrometric monitoring programs targeting 31 ultracool binaries with component spectral types M7-T5. Joint analysis of resolved imaging from Keck Observatory and Hubble Space Telescope and unresolved astrometry from CFHT/WIRCam yields parallactic distances for all systems, robust orbit determinations for 23 systems, and photocenter orbits for 19 systems. As a result, we measure 38 precise individual masses spanning 30-115M_Jup_. We determine a model-independent substellar boundary that is ~70M_Jup_ in mass (~L4 in spectral type), and we validate Baraffe et al. evolutionary model predictions for the lithium-depletion boundary (60M_Jup_ at field ages). Assuming each binary is coeval, we test models of the substellar mass-luminosity relation and find that in the L/T transition, only the Saumon & Marley (2008ApJ...689.1327S) "hybrid" models accounting for cloud clearing match our data. We derive a precise, mass-calibrated spectral type-effective temperature relation covering 1100-2800K. Our masses enable a novel direct determination of the age distribution of field brown dwarfs spanning L4-T5 and 30-70M_Jup_. We determine a median age of 1.3Gyr, and our population synthesis modeling indicates our sample is consistent with a constant star formation history modulated by dynamical heating in the Galactic disk. We discover two triple-brown-dwarf systems, the first with directly measured masses and eccentricities. We examine the eccentricity distribution, carefully considering biases and completeness, and find that low-eccentricity orbits are significantly more common among ultracool binaries than solar-type binaries, possibly indicating the early influence of long-lived dissipative gas disks. Overall, this work represents a major advance in the empirical view of very low-mass stars and brown dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A144
- Title:
- Astrometric observations of Deimos
- Short Name:
- J/A+A/545/A144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between July 2005 and July 2011 Mars Express performed 50 Deimos approaches. 156 SRC images were acquired and used for astrometric (positional) measurements of the small Martian satellite. For this study, we have developed a new technique, where the center-of-figure of the odd-shaped Deimos was determined by fitting the predicted to the observed satellite limb. The prediction of the limb was made based on the moon's known shape model. The camera pointing was verified and corrected by means of background star observations. We obtained a set of spacecraft- centered Deimos coordinates with accuracies between 0.6 and 3.6km (1 sigma). Comparisons with current orbit models indicate that Deimos is ahead or falling behind its predicted position along its track by as much as +3.7km or -4.4km, respectively, depending on the chosen model. Our data may be used to improve the orbit models of the satellite.
- ID:
- ivo://CDS.VizieR/J/A+AS/143/405
- Title:
- Astrometric observations of Helene
- Short Name:
- J/A+AS/143/405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Astrometric photographic positions of the Saturnian satellite Helene obtained from 22 plates taken in 6 nights are presented. The observations are distributed between 5 missions in 1985 and 1987. All positions are compared with those calculated by Jacobson (1999, personal communication). The residuals have mean and standard deviation smaller than 0.25" and 0.30" respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A28
- Title:
- Astrometric observations of Phobos
- Short Name:
- J/A+A/580/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mars Express (MEX) carried out 74 Phobos flybys at distances between 669 and 5579km from April 2008 to August 2011. Images taken with the Super Resolution Channel (SRC) were used to determine the Martian moon's spacecraft-centered right ascension and declination. Image positions of Phobos were measured using the control point and limb fit measurement techniques. Camera pointing and pointing drift were controlled by means of background star observations that were compared to the corresponding positions from the Tycho-2 catalog. Blurred and noisy images were restored by applying an image-based point spread function in a Richardson-Lucy deconvolution. Altogether, we provide 158 astrometric observations of Phobos with estimated uncertainties between 0.224 and 3.405km circular about the direction to the satellite. Control point measurements yield more accurate results than limb fit observations.
- ID:
- ivo://CDS.VizieR/J/other/PBeiO/32.87
- Title:
- Astrometric observations of radio stars
- Short Name:
- J/other/PBeiO/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the data observed in San Juan with the photoelectric Astrolabe Mark II of the Beijing Astronomical Observatory from February, 1992 through March, 1997, the radio stars catalogue in San Juan (RSSJ95) has been compiled. There are 69 radio stars in this catalogue. The Positions of the radio stars are for the epoch of observation and the equinox J2000.0 and a system close that of the system FK5. The mean precisions are +/-2.2ms and +/-0.035" in right ascensions and declinations, respectively. The magnitudes of stars are from 0.9 to 10.7. The declinations are from -2.5{deg} to -60{deg}. The mean epoch is 1995.1. Finally, the comparison results with Hipparcos catalogue and CAMC are given.
