- ID:
- ivo://CDS.VizieR/J/A+A/376/997
- Title:
- Galactic mass-losing AGB stars
- Short Name:
- J/A+A/376/997
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AGB mass-losing sources are easy to identify and to characterize in the near-infrared range (1-5{mu}m). We make use of the near-infrared data acquired by the Japanese space experiment IRTS to study a sample of sources detected in the 2 celestial strips surveyed by the IRTS. Mass-loss rates and distances are estimated for 40 carbon-rich sources and 86 oxygen-rich sources of which 8 are probably of S-type. Although the sample is small, one sees a dependence of the relative contribution of the two kinds of sources to the replenishment of the interstellar medium (ISM) on the galactocentric distance. E.g. from 6 to 8kpc, oxygen-rich sources in our sample contribute 10-12 times as much as carbon rich sources, whereas from 10 to 12kpc, the latters contribute 3-4 times as much as the formers. Therefore, one would expect a gradient in the composition of the ISM between 6 and 12kpc from the Galactic Centre, especially in its dust component. Most of the replenishment (>50%) by AGB stars is due to sources with mass-loss rate larger than 10^-6^M_{sun}_/yr.
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- ID:
- ivo://CDS.VizieR/J/AZh/79/510
- Title:
- Galactic orbits of RR Lyrae variable stars
- Short Name:
- J/AZh/79/510
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used published, high-accuracy, ground-based and satellite proper-motion measurements, a compilation of radial velocities, and photometric distances to compute the spatial velocities and Galactic orbital elements for 174 RR Lyrae (ab) variable stars in the solar neighborhood. The computed orbital elements and published heavy-element abundances are used to study relationships between the chemical, spatial, and kinematic characteristics of nearby RR Lyrae variables. We observe abrupt changes of the spatial and kinematic characteristics at the metallicity [Fe/H]~-0.95 and also when the residual spatial velocities relative to the LSR cross the critical value V_res_~290km/s.
- ID:
- ivo://CDS.VizieR/J/AJ/153/99
- Title:
- Galactic outer disk: a field toward Tombaugh 1
- Short Name:
- J/AJ/153/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We employ optical photometry and high-resolution spectroscopy to study a field toward the open cluster Tombaugh 1, where we identify a complex population mixture that we describe in terms of young and old Galactic thin disks. Of particular interest is the spatial distribution of the young population, which consists of dwarfs with spectral types as early as B6 and is distributed in a blue plume feature in the color-magnitude diagram. For the first time, we confirm spectroscopically that most of these stars are early-type stars and not blue stragglers or halo/thick-disk subdwarfs. Moreover, they are not evenly distributed along the line of sight but crowd at heliocentric distances between 6.6 and 8.2 kpc. We compare these results with present-day understanding of the spiral structure of the Galaxy and suggest that they trace the outer arm. This range of distances challenges current Galactic models adopting a disk cutoff at 14 kpc from the Galactic center. The young dwarfs overlap in space with an older component, which is identified as an old Galactic thin disk. Both young and old populations are confined in space since the disk is warped at the latitude and longitude of Tombaugh 1. The main effects of the warp are that the line of sight intersects the disk and entirely crosses it at the outer arm distance and that there are no traces of the closer Perseus arm, which would then be either unimportant in this sector or located much closer to the formal Galactic plane. Finally, we analyze a group of giant stars, which turn out to be located at very different distances and to possess very different chemical properties, with no obvious relation to the other populations.
- ID:
- ivo://CDS.VizieR/J/ApJ/714/1096
- Title:
- Galactic planetary nebulae
- Short Name:
- J/ApJ/714/1096
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use an extended and homogeneous data set of Galactic planetary nebulae (PNe) to study the metallicity gradients and the Galactic structure and evolution. The most up-to-date abundances, distances (calibrated with Magellanic Cloud PNe), and other parameters have been employed, together with a novel homogeneous morphological classification, to characterize the different PN populations. We studied the {alpha}-element distribution within the Galactic disk, and found that the best selected disk population (i.e., excluding bulge and halo component), together with the most reliable PN distance scale yields to a radial oxygen gradient of {Delta}log(O/H)/{Delta}R_G_=-0.023+/-0.006dex/kpc for the whole disk sample, and of {Delta}log(O/H)/{Delta}R_G_=-0.035+/-0.024, -0.023+/-0.005, and -0.011+/-0.013dex/kpc, respectively for Type I, II, and III PNe, i.e., for high-, intermediate-, and low-mass progenitors. We also extend the Galactic metallicity gradient comparison by revisiting the open cluster [Fe/H] data from high resolution spectroscopy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/447/1673
- Title:
- Galactic post-AGB stars distances
- Short Name:
- J/MNRAS/447/1673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have commenced a detailed analysis of the known sample of Galactic post-asymptotic giant branch (PAGB) objects compiled in the Torun catalogue of Szczerba et al. (2007A&A...469..799S, Cat. J/A+A/469/799), and present, for the first time, homogeneously derived distance determinations for the 209 likely and 87 possible catalogued PAGB stars from that compilation. Knowing distances are essential in determining meaningful physical characteristics for these sources and this has been difficult to determine for most objects previously. The distances were determined by modelling their spectral energy distributions (SEDs) with multiple blackbody curves, and integrating under the overall fit to determine the total distance-dependent flux. This approach was undertaken for consistency as precise spectral types, needed for more detailed fitting, were unknown in the majority of cases. The SED method works because the luminosity of these central stars is very nearly constant from the tip of the AGB phase to the beginning of the white dwarf cooling track. This then enables us to use a standard-candle luminosity to estimate the SED distances. For Galactic thin-disc PAGB objects, we use three luminosity bins based on typical observational characteristics, ranging between 3500 and 12000L_{sun}_. We further adopt a default luminosity of 4000L_{sun}_ for bulge objects and 1700L_{sun}_ for the thick-disc and halo objects. We have also applied the above technique to a further sample of 54 related nebulae not in the current edition of the Torun catalogue. In a follow-up paper, we will estimate distances to the subset of RV Tauri variables using empirical period-luminosity relations, and to the R CrB stars, allowing a population comparison of these objects with the other subclasses of PAGB stars for the first time.
- ID:
- ivo://CDS.VizieR/J/PASP/124/128
- Title:
- Galactic structure toward the Carina tangent
- Short Name:
- J/PASP/124/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This investigation presents a photometric study of the Galactic structure toward the Carina arm tangent. The field is located between 280{deg} and 286{deg} Galactic longitude and -4{deg} to 4{deg} Galactic latitude. All currently available uvby{beta} data are used to obtain homogeneous color excesses and distances for more than 260 stars of spectral types O to G. We present revised distances and average extinction for the open clusters and cluster candidates NGC 3293, NGC 3114, Loden 46, and Loden 112.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/3203
- Title:
- GALAH observational overview
- Short Name:
- J/MNRAS/465/3203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic Archaeology with HERMES (GALAH) Survey is a massive observational project to trace the Milky Way's history of star formation, chemical enrichment, stellar migration and minor mergers. Using high-resolution (R~28,000) spectra taken with the High Efficiency and Resolution Multi-Element Spectrograph (HERMES) instrument at the Anglo-Australian Telescope (AAT), GALAH will determine stellar parameters and abundances of up to 29 elements for up to one million stars. Selecting targets from a colour-unbiased catalogue built from 2MASS, APASS and UCAC4 data, we expect to observe dwarfs at 0.3 to 3kpc and giants at 1 to 10kpc. This enables a thorough local chemical inventory of the Galactic thin and thick disks, and also captures smaller samples of the bulge and halo. In this paper we present the plan, process and progress as of early 2016 for GALAH survey observations. In our first two years of survey observing we have accumulated the largest high-quality spectroscopic data set at this resolution, over 200,000 stars. We also present the first public GALAH data catalogue: stellar parameters (Teff, log(g), [Fe/H], [alpha/Fe]), radial velocity, distance modulus and reddening for 10680 observations of 9860 Tycho-2 stars that may be included in the first Gaia data release.
- ID:
- ivo://CDS.VizieR/J/ApJ/748/15
- Title:
- Galaxy distances with the Fundamental Manifold
- Short Name:
- J/ApJ/748/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We demonstrate how the Fundamental Manifold (FM) can be used to cross-calibrate distance estimators even when those "standard candles" are not found in the same galaxy. Such an approach greatly increases the number of distance measurements that can be utilized to check for systematic distance errors and the types of estimators that can be compared. Here we compare distances obtained using Type Ia supernova (SN Ia), Cepheids, surface brightness fluctuations, the luminosity of the tip of the red giant branch, circumnuclear masers, eclipsing binaries, RR Lyrae stars, and the planetary nebulae luminosity functions. We find no significant discrepancies (differences are <2{sigma}) between distance methods, although differences at the ~10% level cannot yet be ruled out. The potential exists for significant refinement because the data used here are heterogeneous B-band magnitudes that will soon be supplanted by homogeneous, near-infrared magnitudes. We illustrate the use of FM distances to (1) revisit the question of the metallicity sensitivity of various estimators, confirming the dependence of SN Ia distances on host galaxy metallicity, and (2) provide an alternative calibration of H_0_ that replaces the classical ladder approach in the use of extragalactic distance estimators with one that utilizes data over a wide range of distances simultaneously.
- ID:
- ivo://CDS.VizieR/V/117A
- Title:
- Geneva-Copenhagen Survey of Solar neighbourhood
- Short Name:
- V/117A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (from paper II, 2007) Ages, metallicities, space velocities, and Galactic orbits of stars in the Solar neighbourhood are fundamental observational constraints on models of galactic disk evolution. Understanding and minimising systematic errors and sample selection biases in the data is crucial for their interpretation. We aim to consolidate the calibrations of uvbyb photometry into T_eff_, [Fe/H], distance, and age for F and G stars and rediscuss the results of the Geneva-Copenhagen Survey (GCS, Nordstrom et al., 2004, paper I) in terms of the evolution of the disk. We use recent V-K photometry, angular diameters, high-resolution spectroscopy, Hipparcos parallaxes, and extensive numerical simulations to re-examine and verify the temperature, metallicity, distance, and reddening calibrations for the uvbyb system. We also highlight the selection effects inherent in the apparent-magnitude limited GCS sample. We substantially improve the T_eff_ and [Fe/H] calibrations for early F stars, where spectroscopic temperatures have large systematic errors. A slight offset of the GCS photometry and the non-standard helium abundance of the Hyades invalidate its use for checking metallicity or age scales; however, the distances, reddenings, metallicities, and age scale for GCS field stars require minor corrections only. Our recomputed ages are in excellent agreement with the independent determinations by Takeda et al. (2007ApJS..168..297T), indicating that isochrone ages can now be reliably determined. The revised G-dwarf metallicity distribution remains incompatible with closed-box models, and the age-metallicity relation for the thin disk remains almost flat, with large and real scatter at all ages sigma_intrinsic=0.20 dex). Dynamical heating of the thin disk continues throughout its life; specific in-plane dynamical effects dominate the evolution of the U and V velocities, while the W velocities remain random at all ages. When assigning thick and thin-disk membership for stars from kinematic criteria, parameters for the oldest stars should be used to characterise the thin disk.
- ID:
- ivo://CDS.VizieR/V/130
- Title:
- Geneva-Copenhagen Survey of Solar neighbourhood III
- Short Name:
- V/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ages, chemical compositions, velocity vectors, and Galactic orbits for stars in the solar neighbourhood are fundamental test data for models of Galactic evolution. The Geneva-Copenhagen Survey of the Solar neighbourhood (Nordstrom et al. 2004A&A...418..989N; GCS), a magnitude-complete, kinematically unbiased sample of 16,682 nearby F and G dwarfs, is the largest available sample with complete data for stars with ages spanning that of the disk. We aim to improve the accuracy of the GCS data by implementing the recent revision of the Hipparcos parallaxes. The new parallaxes yield improved astrometric distances for 12,506 stars in the GCS. We also use the parallaxes to verify the distance calibration for uvbyHbeta photometry by Holmberg et al. (2007A&A...475..519H; GCS II, Cat. VI/117). We add new selection criteria to exclude evolved cool stars giving unreliable results and derive distances for 3,580 stars with large parallax errors or not observed by Hipparcos. We also check the GCS II scales of T_eff_ and [Fe/H] and find no need for change. From the new distances we compute revised Mv, U, V, W, and Galactic orbital parameters for 13,520 GCS stars. We also recompute stellar ages with the new values of Mv from the Padova stellar evolution models used in GCS I-II, and compare them with ages from the Yale-Yonsei and Victoria-Regina models. Finally, we compare the observed age-velocity relation in W with three simulated disk heating scenarios to show the potential of the data. With these revisions, the basic data for the GCS stars should now be as reliable as is possible with existing techniques. Further improvement must await consolidation of the T_eff_ scale from angular diameters and fluxes, and the Gaia trigonometric parallaxes. We discuss the conditions for improving computed stellar ages from new input data, and for distinguishing different disk heating scenarios from data sets of the size and precision of the GCS.
