- 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.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/889/21
- Title:
- Galactic planetary nebulae with Gaia data
- Short Name:
- J/ApJ/889/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We matched the astrometry of central stars (CSs) of spectroscopically confirmed Galactic planetary nebulae (PNe) with DR2 Gaia parallaxes (p), finding 430 targets in common with p>0 and |{sigma}_p_/p|<1. A catalog of PNe whose CSs have DR2 Gaia parallaxes is presented in Table 1. We compared DR2 parallaxes with those in the literature, finding good correlation between the two samples. We used PNe parallaxes to calibrate the Galactic PN distance scale. Restricting the sample to objects with 20% parallax accuracy, we derive the distance scale log(R_pc_)=-(0.226+/-0.0155)xlog(S_H{beta}_)-(3.920+/-0.215), which represents a notable improvement with respect to previous ones. We found that the ionized mass versus optical thickness distance scale for Galactic PNe is not as constrained by the Gaia calibrators, but gives important insight into the nature of the PNe, and is essential to define the domain for our distance scale application. We placed the CSs whose distance has been determined directly by parallax on the HR diagram, and found that their location on the post-asymptotic-giant-branch (AGB) H-burning evolutionary tracks is typical for post-AGB stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/700/523
- Title:
- Galactic star clusters in SDSS. II. Colors.
- Short Name:
- J/ApJ/700/523
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform an extensive test of theoretical stellar models for main-sequence (MS) stars in ugriz, using cluster fiducial sequences obtained in the previous paper of this series. We generate a set of isochrones using the Yale Rotating Evolutionary Code with updated input physics, and derive magnitudes and colors in ugriz from MARCS model atmospheres. These models match cluster MSs over a wide range of metallicity within the errors of the adopted cluster parameters. However, we find a large discrepancy of model colors at the lower MS (T_eff_<~4500K) for clusters at and above solar metallicity. We also reach similar conclusions using the theoretical isochrones of Girardi et al. and Dotter et al., but our new models are generally in better agreement with the data. Using our theoretical isochrones, we also derive MS-fitting distances and turnoff ages for five key globular clusters, and demonstrate the ability to derive these quantities from photometric data in the Sloan Digital Sky Survey. In particular, we exploit multiple color indices (g-r, g-i, and g-z) in the parameter estimation, which allows us to evaluate internal systematic errors. Our distance estimates, with an error of {sigma}_(m-M)_=0.03-0.11mag for individual clusters, are consistent with Hipparcos-based subdwarf-fitting distances derived in the Johnson-Cousins or Stromgren photometric systems.
- 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/A+A/638/A145
- Title:
- GALAH survey. FGK binary stars
- Short Name:
- J/A+A/638/A145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary stellar systems form a large fraction of the Galaxy's stars. They are useful as laboratories for studying the physical processes taking place within stars, and must be correctly taken into account when observations of stars are used to study the structure and evolution of the Galaxy. We present a sample of 12760 well-characterised double-lined spectroscopic binaries that are appropriate for statistical studies of the binary populations. They were detected as SB2s using a t-distributed stochastic neighbour embedding (t-SNE) classification and a cross-correlation analysis of GALAH spectra. This sample consists mostly of dwarfs, with a significant fraction of evolved stars and several dozen members of the giant branch. To compute parameters of the primary and secondary star (Teff[1,2], logg[1,2], [Fe/H], Vr[1,2], vmic[1,2], vbroad[1,2], R[1,2], and E(B-V)), we used a Bayesian approach that includes a parallax prior from Gaia DR2, spectra from GALAH, and apparent magnitudes from APASS, Gaia DR2, 2MASS, and WISE. The derived stellar properties and their distributions show trends that are expected for a population of close binaries (a<10AU) with mass ratios 0.5<=q<=1. The derived metallicity of these binary stars is statistically lower than that of single dwarf stars from the same magnitude-limited sample.
- ID:
- ivo://CDS.VizieR/J/A+AS/141/123
- Title:
- Galaxies behind Southern Milky Way
- Short Name:
- J/A+AS/141/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A deep optical galaxy search in the southern Milky Way - aimed at reducing the width of the Zone of Avoidance - revealed 3279 galaxy candidates on the IIIaJ film copies of the ESO/SRC survey above the diameter limit of D greater than approximately 0.2 arcmin. Only 112 (3.4%) were previously catalogued. The surveyed region (266<l<296 and -10<b<+8) lies in the extension of the Hydra and Antlia clusters. Optical properties of the unveiled galaxies such as positions, diameters, magnitudes, morphological types are given in Table 1. Cross-identifications with the IRAS PSC (Cat. <II/125>) are given in Table 2.
- ID:
- ivo://CDS.VizieR/J/A+A/380/441
- Title:
- Galaxies behind Southern Milky Way. II.
- Short Name:
- J/A+A/380/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this second paper of the catalogue series of galaxies behind the southern Milky Way, we report on the deep optical galaxy search in the Crux region (289{deg}<~l<~318{deg} and -10{deg}<~b<~10{deg}) and the Great Attractor region (316{deg}<~l<~338{deg} and -10{deg}<~b<~10{deg}). The galaxy catalogues are presented, a brief description of the galaxy search given, as well as a discussion on the distribution and characteristics of the uncovered galaxies. A total of 8183 galaxies with major diameters D>~0.2 arcmin were identified in this ~850 square degree area: 3759 galaxies in the Crux region and 4423 galaxies in the Great Attractor region. Of the 8183 galaxies, 229 (2.8%) were catalogued before in the optical (3 in radio) and 251 galaxies have a reliable (159), or likely (92) cross-identification in the IRAS Point Source Catalogue (3.1%). A number of prominent overdensities and filaments of galaxies are identified. They are not correlated with the Galactic foreground extinction and hence indicative of extragalactic large-scale structures. Redshifts obtained at the South African Astronomical Observatory (SAAO) for 518 of the newly catalogued galaxies in the Crux and Great Attractor regions (Fairall et al., 1998, Cat. <J/A+AS/127/463>; Woudt et al., 1999, Cat. <J/A+A/352/39>) confirm distinct voids and clusters in the area here surveyed. With this optical galaxy search, we have reduced the width of the optical `Zone of Avoidance' for galaxies with extinction-corrected diameters larger than 1.3' from extinction levels A_B>~1.0mag to A_B>~3.0mag: the remaining optical Zone of Avoidance is now limited by |b|<~3{deg} (see Fig. 16).
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3943
- Title:
- galaxies 2D phot. decompositions in SDSS-DR7
- Short Name:
- J/MNRAS/446/3943
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 2D, point spread function-corrected de Vacouleurs, Sersic, de Vacouleurs+Exponential, and Sersic+Exponential fits of ~7x10^5^ spectroscopically selected galaxies drawn from the Sloan Digital Sky Survey (SDSS) Data Release 7. Fits are performed for the SDSS r band utilizing the fitting routine galfit and analysis pipeline pymorph. We compare these fits to prior catalogues. Fits are analysed using a physically motivated flagging system. The flags suggest that more than 90 percent of two-component fits can be used for analysis. We show that the fits follow the expected behaviour for early and late galaxy types. The catalogues provide a robust set of structural and photometric parameters for future galaxy studies. We show that some biases remain in the measurements, e.g. the presence of bars significantly affect the bulge measurements although the bulge ellipticity may be used to separate barred and non-barred galaxies, and about 15 percent of bulges of two-component fits are also affected by resolution. The catalogues are available in electronic format. We also provide an interface for generating postage stamp images of the 2D model and residual as well as the 1D profile. These images can be generated for a user-uploaded list of galaxies on demand.
- ID:
- ivo://CDS.VizieR/J/other/AstBu/69.247
- Title:
- Galaxies in Lynx-Cancer void
- Short Name:
- J/other/AstBu/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we present the results of photometrical study of 85 objects from the updated sample of galaxies residing in the nearby Lynx-Cancer void. The images in filters u,g,r,i from the Sloan Digital Sky Survey database are used for photometry. The following model-independent parameters are obtained: integrated magnitudes and colours, effective radii and the respective surface brightnesses, optical and Holmberg radii. On results of the radial surface brightness profile analysis, their central values and scalelengths of model discs are derived. The colours of the outer parts of void galaxies are examined and compared to those of the model evolutionary tracks of the PEGASE2 package. This allowed to obtain estimates of the time since the epoch of star formation T_SF_. Among the latter group, the low-luminosity objects with M_B_>-13.2 dominate. The derived integrated absolute magnitudes and colours are used for galaxy stellar mass estimates. All available data on integrated galaxy HI fluxes are used to derive their parameter M(HI)/L_B_ and to estimate their gas mass-fraction. The small ~10% subgroup of the most gas-rich galaxies, with M(HI)/L_B_>2.5, shows gas mass-fractions reaching (94-99)%. Many of these objects also show atypically blue colours of their outer parts. To check possible statistical differences of void galaxy properties and galaxy samples formed with more general criteria, we compared the void sample galaxy parameters with those of 195 galaxies from the Equatorial Survey (ES), formed as a part of the blind HI survey HIPASS. In the common luminosity range (-18.5<M_g_<-13.5) the compared samples show similarity. The lowest luminosity void galaxies differ from the main ES sample. However, there are also ~7% faint so called 'inchoate' galaxies among ES sample with the elevated parameter M(HI)/L_B_, majority of which are situated far from massive neighbours and are probably the analogs of void galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/121/1840
- Title:
- Galaxies in Q0835+580 and Q1126+101 fields
- Short Name:
- J/AJ/121/1840
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have previously identified an excess population of predominantly red galaxies around a sample of 31 radio-loud quasars (RLQs) at 1<z<2. Here we show that these fields have a surface density of extremely red objects (EROs, with R-K>6) 2.7 times higher than the general field. Assuming these EROs are passively evolved galaxies at the quasar redshifts, they have characteristic luminosities of only ~L*. Only one of four RLQ fields has an excess of J-K-selected EROs with J-K>2.5; thus, those objects are mostly unrelated to the quasars. We also present new multiwavelength data and analyses on the fields of four of these quasars at z_q_~1.54, obtained to build more detailed pictures of the environments of these quasars and the galaxies within them.
