- ID:
- ivo://CDS.VizieR/J/A+A/584/A92
- Title:
- Galactic Cold Cores. IV. Cold sub-mm sources
- Short Name:
- J/A+A/584/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For the project Galactic cold cores, Herschel photometric observations were carried out as a follow-up of cold regions of interstellar clouds previously identified with the Planck satellite. The aim of the project is to derive the physical properties of the population of cold sources and to study its connection to ongoing and future star formation. We build a catalogue of cold sources within the clouds in 116 fields observed with the Herschel PACS and SPIRE instruments. We wish to determine the general physical characteristics of the cold sources and to examine the correlations with their host cloud properties. From Herschel data, we compute colour temperature and column density maps of the fields. We estimate the distance to the target clouds and provide both uncertainties and reliability flags for the distances. The getsources multi-wavelength source extraction algorithm is employed to build a catalogue of several thousands of cold sources. Mid-infrared data are used along with a colour and position criteria to separate starless and protostellar sources. We also propose another classification method based on sub-millimetre temperature profiles. We analyse the statistical distributions of the physical properties of the source samples. We provide a catalogue of ~4000 cold sources within or near star forming clouds, most of which are located either in nearby molecular complexes (<1kpc) or in star forming regions of the nearby galactic arms (~2kpc). About 70% of the sources have a size compatible with an individual core, and 35% of those sources are likely gravitationally bound. Significant statistical differences in physical properties are found between starless and protostellar sources, in column density - dust temperature, mass - size, and mass - dust temperature diagrams. The core mass functions are very similar to those previously reported for other regions. On statistical grounds we find that gravitationally bound sources have higher background column densities (median N_bg_(H_2_)~5x10^21^cm-2) than unbound sources (median N_bg_(H_2_)~3x10^21^cm-2). These values of N_bg_(H_2_) are higher for larger dust temperature of the external layers of the parent cloud. However, only in few cases do we find clear N_bg_(H_2_) thresholds for the presence of cores. The dust temperature of cloud external layers shows clear variations with galactic location, as possibly do the source temperatures. Our data support a more complex view of star formation than in the simple idea of a column density threshold. They show a clear influence of the surrounding UV-visible radiation on how cores distribute in their host clouds, with possible variations on the Galactic scale.
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- ID:
- ivo://CDS.VizieR/J/A+A/584/A93
- Title:
- Galactic cold cores. V. Dust opacity
- Short Name:
- J/A+A/584/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The project Galactic Cold Cores has carried out Herschel photometric observations of interstellar clouds where Planck satellite survey has located cold and compact clumps. The sources represent different stages of cloud evolution from starless clumps to protostellar cores and are located in different Galactic environments. We examine this sample of 116 Herschel fields to estimate the submillimetre dust opacity and to look for variations that could be attributed to the evolutionary stage of the sources or to environmental factors, including the location within the Galaxy. The submillimetre dust opacity is derived from Herschel data and near-infrared observations of the reddening of background stars are converted to near-infrared optical depth. We investigate the systematic errors affecting these parameters and use modelling to make corrections for the expected biases. The ratio of 250{mu}m and J band opacities is correlated with the Galactic location and the star formation activity. Local variations in the ratio {tau}(250{mu}m)/{tau}(J) are searched using the correlation plots and maps of the opacity ratio. We find a median ratio of {tau}(250{mu}m)/{mu}(J)=(1.6+/-0.2)*10^-3^, which is more than three times the mean value reported for the diffuse medium. Assuming an opacity spectral index {beta}=1.8 instead of {beta}=2.0, the value would be smaller by ~30%. No significant systematic variation is detected with Galactocentric distance or with Galactic height. Examination of the {tau}(250{mu}m)/{tau}(J) maps reveals half a dozen fields with clear indications of local increase of submillimetre opacity, up to {tau}(250{mu}m)/{tau}(J)~4*10^-3^, towards the densest clumps. These are all nearby fields with spatially resolved clumps of high column density. We interpret the increase in the far-infrared opacity as a sign of grain growth in the densest and coldest regions of interstellar clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A94
- Title:
- Galactic cold cores. VI. List of Herschel fields
- Short Name:
- J/A+A/584/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic Cold Cores project has carried out Herschel photometric observations of 116 fields where the Planck survey has found signs of cold dust emission. The fields contain sources in different environments and different phases of star formation. Previous studies have revealed variations in their dust submillimetre opacity. The aim is to measure the value of dust opacity spectral index and to understand its variations spatially and with respect to other parameters, such as temperature, column density, and Galactic location. The dust opacity spectral index {beta} and the dust colour temperature T are derived using Herschel and Planck data. The relation between {beta} and T is examined for the whole sample and inside individual fields.
- ID:
- ivo://CDS.VizieR/J/MNRAS/492/3408
- Title:
- Galactic disc RR Lyrae stars
- Short Name:
- J/MNRAS/492/3408
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematical study of 314 RR Lyrae stars in the solar neighbourhood using the publicly available photometric, spectroscopic, and Gaia DR2 astrometric data to explore their distribution in the Milky Way. We report an overdensity of 22 RR Lyrae stars in the solar neighbourhood at a pericentre distance of between 5 and 9kpc from the Galactic Centre. Their orbital parameters and their chemistry indicate that these 22 variables share the kinematics and the [Fe/H] values of the Galactic disc, with an average metallicity and tangential velocity of [Fe/H]=-0.60dex and v_theta_=241km/s, respectively. From the distribution of the Galactocentric spherical velocity components, we find that these 22 disc-like RR Lyrae variables are not consistent with the Gaia Sausage (Gaia-Enceladus), unlike almost half of the local RR Lyrae stars. Chemical information from the literature shows that the majority of the selected pericentre-peak RR Lyrae variables are alpha-poor, a property shared by typically much younger stars in the thin disc. Using the available photometry, we rule out a possible misclassification with the known classical and anomalous Cepheids. The similar kinematic, chemical, and pulsation properties of these disc RR Lyrae stars suggest they share a common origin. In contrast, we find that the RR Lyrae stars associated with the Gaia- Enceladus based on their kinematics and chemical composition show a considerable metallicity spread in the old population (approximately 1dex).
- ID:
- ivo://CDS.VizieR/J/A+A/418/551
- Title:
- Galactic disk stars abundances and velocities
- Short Name:
- J/A+A/418/551
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed the detailed analysis of 174 high-resolution spectra of FGK dwarfs obtained with the ELODIE echelle spectrograph at the Observatoire de Haute-Provence. Abundances of Fe, Si and Ni have been determined from equivalent widths under LTE approximation, whereas abundances of Mg have been determined under NLTE approximation using equivalent widths of 4 lines and profiles of 5 lines. Spatial velocities with an accuracy better than 1kms, as well as orbits, have been computed for all stars.
- ID:
- ivo://CDS.VizieR/J/A+A/480/91
- Title:
- Galactic disk stars vertical distribution. IV.
- Short Name:
- J/A+A/480/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the parameters of 891 stars, mostly clump giants, including atmospheric parameters, distances, absolute magnitudes, spatial velocities, galactic orbits and ages. One part of this sample consists of local giants, within 100pc, with atmospheric parameters either estimated from our spectroscopic observations at high resolution and high signal-to-noise ratio, or retrieved from the literature. The other part of the sample includes 523 distant stars, spanning distances up to 1 kpc in the direction of the North Galactic Pole, for which we have estimated atmospheric parameters from high resolution but low signal-to-noise Echelle spectra. This new sample is kinematically unbiased, with well-defined boundaries in magnitude and colours. We revisit the basic properties of the Galactic thin disk as traced by clump giants. We find the metallicity distribution to be different from that of dwarfs, with fewer metal-rich stars. We find evidence for a vertical metallicity gradient of -0.31dex/kpc and for a transition at 4-5Gyr in both the metallicity and velocities. The age - metallicity relation (AMR), which exhibits a very low dispersion, increases smoothly from 10 to 4Gyr, with a steeper increase for younger stars. The age-velocity relation (AVR) is characterized by the saturation of the V and W dispersions at 5Gyr, and continuous heating in U.
- ID:
- ivo://CDS.VizieR/J/A+A/493/785
- Title:
- Galactic disk stellar populations from ISOGAL
- Short Name:
- J/A+A/493/785
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify the stellar populations (mostly red giants and young stars) detected in the ISOGAL survey at 7 and 15um towards a field (LN45) in the direction l=-45, b=0.0. The sources detected in the survey of the Galactic plane by the Infrared Space Observatory were characterised based on colour-colour and colour-magnitude diagrams. We combine the ISOGAL catalogue with the data from surveys such as 2MASS and GLIMPSE. Interstellar extinction and distance were estimated using the red clump stars detected by 2MASS in combination with the isochrones for the AGB/RGB branch. Absolute magnitudes were thus derived and the stellar populations identified from their absolute magnitudes and their infrared excess. A standard approach to analysing the ISOGAL disc observations has been established. We identify several hundred RGB/AGB stars and 22 candidate young stellar objects in the direction of this field in an area of 0.16deg^2^. An overdensity of stellar sources is found at distances corresponding to the distance of the Scutum-Crux spiral arm. In addition, we determined mass-loss rates of AGB-stars using dust radiative transfer models from the literature.
- ID:
- ivo://CDS.VizieR/J/ApJ/653/1325
- Title:
- Galactic distribution of infrared dark clouds
- Short Name:
- J/ApJ/653/1325
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using ^13^CO(J=1-0) molecular line emission (112GHz) from the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (BU-FCRAO GRS), we have established kinematic distances to 313 infrared dark clouds (IRDCs) by matching the morphology of the molecular line emission in distinct velocity channels to their mid-infrared extinction.
- ID:
- ivo://CDS.VizieR/J/ApJ/680/349
- Title:
- Galactic distribution of IRDCs
- Short Name:
- J/ApJ/680/349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CS(2-1) measurements toward a large sample of fourth Galactic quadrant infrared dark clouds (IRDCs) were made with the Australia Telescope National Facility Mopra telescope in order to establish their kinematic distances and Galactic distribution. Due to its large critical density, CS unambiguously separates the dense IRDCs from more diffuse giant molecular clouds. The fourth-quadrant IRDCs show a pronounced peak in their radial galactocentric distribution at R=6kpc. The first-quadrant IRDC distribution (traced by ^13^CO emission) also shows a peak, but at a galactocentric radius of R=5kpc rather than 6kpc. The reliability of the MSX IRDC catalog by Simon and coworkers is estimated by using the CS detection rate of IRDC candidates. The overall reliability is at least 58%, and increases to near 100% for high contrasts, Galactic longitudes within ~30{deg} of the Galactic center, and large mid-IR backgrounds. A significant fraction of our IRDC sample (14%) showed two CS velocity components, which probably represent two distinct IRDCs along the same line of sight.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/41
- Title:
- Galactic EB stars with eccentric orbits based on ETDs
- Short Name:
- J/ApJS/235/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A comprehensive catalog of 623 galactic eclipsing binary (EB) systems with eccentric orbits is presented with more than 2830 times of minima determined from the archived photometric data by various sky-survey projects and new photometric measurements. The systems are divided into two groups according to whether the individual system has a GCVS name or not. All the systems in both groups are further classified into three categories (D, A, and A+III) on the basis of their eclipse timing diagrams: 453 D systems showing just constantly displaced secondary minima, 139 A systems displaying only apsidal motion (AM), and 31 A+III systems exhibiting both AM and light-time effects. AM parameters for 170 systems (A and A+III systems) are consistently calculated and cataloged with basic information for all systems. Some important statistics for the AM parameters are discussed and compared with those derived for the eccentric EB systems in the Large and Small Magellanic Clouds.