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981. COBE DIRBE Point Source Catalog
ID:
ivo://CDS.VizieR/J/ApJS/154/673
Title:
COBE DIRBE Point Source Catalog
Short Name:
J/ApJS/154/673
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the COBE DIRBE Point Source Catalog, an all-sky catalog containing infrared photometry in 10 bands from 1.25 microns to 240 microns for 11788 of the brightest near and mid-infrared point sources in the sky. Since DIRBE had excellent temporal coverage (100-1900 independent measurements per object during the 10 month cryogenic mission), the Catalog also contains information about variability at each wavelength, including amplitudes of variation observed during the mission. Since the DIRBE spatial resolution is relatively poor (0.7{deg}), we have carefully investigated the question of confusion, and have flagged sources with infrared-bright companions within the DIRBE beam. In addition, we filtered the DIRBE light curves for data points affected by companions outside of the main DIRBE beam but within the `sky' portion of the scan. At high Galactic latitudes (|b|>5{deg}), the Catalog contains essentially all of the unconfused sources with flux densities greater than 90, 60, 60, 50, 90, and 165 Jy at 1.25, 2.2, 3.5, 4.9, 12, and 25 microns, respectively, corresponding to magnitude limits of approximately 3.1, 2.6, 1.7, 1.3, -1.3, and -3.5. At longer wavelengths and in the Galactic Plane, the completeness is less certain because of the large DIRBE beam and possible contributions from extended emission. The Catalog also contains the names of the sources in other catalogs, their spectral types, variability types, and whether or not the sources are known OH/IR stars. We discuss a few remarkable objects in the Catalog.
982. CO-CAVITY pilot survey. CO spectra
ID:
ivo://CDS.VizieR/J/A+A/658/A124
Title:
CO-CAVITY pilot survey. CO spectra
Short Name:
J/A+A/658/A124
Date:
22 Feb 2022
Publisher:
CDS
Description:
Voids are the most under-dense large-scale regions in the Universe. Galaxies inhabiting voids are one of the keys to understand the intrinsic processes of galaxy evolution, as external factors such as multiple galaxy mergers or a dense self-collapsing environment are negligible. We present the first molecular gas mass survey of void galaxies. We compare these new data, together with data for the atomic gas mass (MHI) and star formation rate (SFR) from the literature to those of galaxies in filaments and walls in order to better understand how molecular gas and star formation are related to the large-scale environment. We observed at the IRAM 30-m telescope the CO(1-0) and CO(2-1) emission of 20 void galaxies selected from the VoidGalaxy Survey (VGS), with a stellar mass range from 108.5to 1010.3M. We detected 15 objects in at least one CO line. We compare the molecular gas mass (MH2), the star formation efficiency (SFE=SFR/MH2), the atomic gas mass, the molecular-to-atomic gas-mass ratio, and the specific star formation rate (sSFR) of the void galaxies with two control samples of galaxies in filaments and walls,selected from xCOLD GASS and EDGE-CALIFA, for different stellar mass bins and taking the star formation activity into account. In general, we do not find any significant differences between void galaxies and the control sample. In particular, we do not find any evidence for a difference in the molecular gas mass or molecular gas mass fraction. Also for the other parameters (SFE,atomic gas mass, molecular-to-atomic gas mass ratio, and sSFR) we find similar (within the errors) mean values between void, and filament and wall galaxies when limiting the sample to star-forming galaxies. We find no evidence for an enhanced sSFR in void galaxies. Some tentative differences emerge when studying trends with stellar mass: The SFE of void galaxies might be lower than in filament and wall galaxies for low stellar masses, and there might be a trend of increasing deficiency in the HI content in void galaxies compared to galaxies in filaments and walls for higher stellar masses, accompanied by an increase in the molecular-to-atomic gas-mass ratio. However, all trends with stellar mass are based on a low number of galaxies and need to be confirmed for a larger sample. The results for the molecular gas mass for a sample of 20 voids galaxies allowed us, for the first time, to make a statistical comparison to galaxies in filaments and walls. We do not find any significant differences of the molecular gas properties and the SFE, but we note that a larger sample is necessary to confirm this and be sensitive to subtle trends.
983. 13CO (1-0) data molecular cloud catalogue
ID:
ivo://CDS.VizieR/J/A+A/654/A144
Title:
13CO (1-0) data molecular cloud catalogue
Short Name:
J/A+A/654/A144
Date:
22 Feb 2022
Publisher:
CDS
Description:
New-generation spectroscopic surveys of the Milky Way plane have been revealing the structure of the interstellar medium, allowing the simultaneous study of dense structures from single star-forming objects or systems to entire spiral arms. The good sensitivity of the new surveys and the development of dedicated algorithms now enable building extensive catalogues of molecular clouds and deriving good estimates of their physical properties. This allows studying the behaviour of these properties across the Galaxy. We present the catalogue of molecular clouds extracted from the ^13^CO (1-0) data cubes of the Forgotten Quadrant Survey, which mapped the Galactic plane in the range 220{deg}<l<240{deg}, and -2.5{deg}<b<0{deg} in ^12^CO (1-0) and ^13^CO (1-0). We compared the properties of the clouds of our catalogue with those of other catalogues. The catalogue contains 87 molecular clouds for which the main physical parameters such as area, mass, distance, velocity dispersion, and virial parameter were derived. These structures are overall less extended and less massive than the molecular clouds identified in the ^12^CO (1-0) data-set because they trace the brightest and densest part of the ^12^CO (1-0) clouds. Conversely, the distribution of aspect ratio, equivalent spherical radius, velocity dispersion, and virial parameter in the two catalogues are similar. The mean value of the mass surface density of molecular clouds is 87+/-55M_{sun}_/pc^2^ and is almost constant across the galactocentric radius, indicating that this parameter, which is a proxy of star formation, is mostly affected by local conditions. In data of the Forgotten Quadrant Survey, we find a good agreement between the total mass and velocity dispersion of the clouds derived from ^12^CO (1-0) and ^13^CO (1-0). This is likely because in the surveyed portion of the Galactic plane, the H_2_ column density is not particularly high, leading to a CO emission with a not very high optical depth. This mitigates the effects of the different line opacities between the two tracers on the derived physical parameters. This is a common feature in the outer Galaxy, but our result cannot be readily generalised to the entire Milky Way because regions with higher particle density could show a different behaviour.
984. CO large-field observations around l=150{deg}
ID:
ivo://CDS.VizieR/J/ApJ/838/49
Title:
CO large-field observations around l=150{deg}
Short Name:
J/ApJ/838/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present large-field (4.25x3.75deg^2^) mapping observations toward the Galactic region centered at l=150{deg},b=3.5{deg} in the J=1-0 emission line of CO isotopologues (^12^CO, ^13^CO, and C^18^O), using the 13.7m millimeter-wavelength telescope of the Purple Mountain Observatory. Based on the ^13^CO observations, we reveal a filamentary cloud in the Local Arm at a velocity range of -0.5 to 6.5km/s. This molecular cloud contains 1 main filament and 11 sub-filaments, showing the so-called "ridge-nest" structure. The main filament and three sub-filaments are also detected in the C^18^O line. The velocity structures of most identified filaments display continuous distribution with slight velocity gradients. The measured median excitation temperature, line width, length, width, and linear mass of the filaments are ~9.28K, 0.85km/s, 7.30pc, 0.79pc, and 17.92M_{sun}_/pc, respectively, assuming a distance of 400pc. We find that the four filaments detected in the C^18^O line are thermally supercritical, and two of them are in the virialized state, and thus tend to be gravitationally bound. We identify in total 146 ^13^CO clumps in the cloud, about 77% of the clumps are distributed along the filaments. About 56% of the virialized clumps are found to be associated with the supercritical filaments. Three young stellar object candidates are also identified in the supercritical filaments, based on the complementary infrared data. These results indicate that the supercritical filaments, especially the virialized filaments, may contain star-forming activities.
985. Collinder 261 Chandra sources & optical counterparts
ID:
ivo://CDS.VizieR/J/ApJ/837/130
Title:
Collinder 261 Chandra sources & optical counterparts
Short Name:
J/ApJ/837/130
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first X-ray study of Collinder 261 (Cr261), which at an age of 7Gyr is one of the oldest open clusters known in the Galaxy. Our observation with the Chandra X-Ray Observatory is aimed at uncovering the close interacting binaries in Cr261, and reaches a limiting X-ray luminosity of L_X_~4x10^29^erg/s (0.3-7keV) for stars in the cluster. We detect 107 sources within the cluster half-mass radius r_h_, and we estimate that among the sources with L_X_>~10^30^erg/s, ~26 are associated with the cluster. We identify a mix of active binaries and candidate active binaries, candidate cataclysmic variables, and stars that have "straggled" from the main locus of Cr261 in the color-magnitude diagram. Based on a deep optical source catalog of the field, we estimate that Cr261 has an approximate mass of 6500M_{sun}_, roughly the same as the old open cluster NGC6791. The X-ray emissivity of Cr261 is similar to that of other old open clusters, supporting the trend that they are more luminous in X-rays per unit mass than old populations of higher (globular clusters) and lower (the local neighborhood) stellar density. This implies that the dynamical destruction of binaries in the densest environments is not solely responsible for the observed differences in X-ray emissivity.
986. Collinder 69 X-ray sources
ID:
ivo://CDS.VizieR/J/A+A/526/A21
Title:
Collinder 69 X-ray sources
Short Name:
J/A+A/526/A21
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the first paper of a series devoted to the {lambda} Orionis star-forming region, Orion's Head, from the X-ray perspective. Our final aim is to provide a comprehensive view of this complex region, which includes several distinct associations and dark clouds. We aim to uncover the population of the central, young star cluster Collinder 69, and in particular those diskless Class III objects not identified by previous surveys based on near- and mid-infrared searches, and to establish the X-ray luminosity function for the association.
987. Collisions of terrestrial worlds
ID:
ivo://CDS.VizieR/J/AJ/153/165
Title:
Collisions of terrestrial worlds
Short Name:
J/AJ/153/165
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of an investigation into the occurrence and properties (stellar age and mass trends) of low- mass field stars exhibiting extreme mid-infrared (MIR) excesses (LIR/L*~>~0.01). Stars for the analysis were initially selected from the Motion Verified Red Stars (MoVeRS) catalog of photometric stars with Sloan Digital Sky Survey, 2MASS, and WISE photometry and significant proper motions. We identify 584 stars exhibiting extreme MIR excesses, selected based on an empirical relationship for main-sequence W1-W3 colors. For a small subset of the sample, we show, using spectroscopic tracers of stellar age (H{alpha} and LiI) and luminosity class, that the parent sample is most likely comprised of field dwarfs (>1Gyr). We also develop the Low-mass Kinematics (LoKi) galactic model to estimate the completeness of the extreme MIR excess sample. Using Galactic height as a proxy for stellar age, the completeness-corrected analysis indicates a distinct age dependence for field stars exhibiting extreme MIR excesses. We also find a trend with stellar mass (using r-z color as a proxy). Our findings are consistent with the detected extreme MIR excesses originating from dust created in a short-lived collisional cascade (<100000-years) during a giant impact between two large planetismals or terrestrial planets. These stars with extreme MIR excesses also provide support for planetary collisions being the dominant mechanism in creating the observed Kepler dichotomy (the need for more than a single mode, typically two, to explain the variety of planetary system architectures Kepler has observed), rather than different formation mechanisms.
988. Color/age/metallicity gradients of E galaxies
ID:
ivo://CDS.VizieR/J/ApJ/766/109
Title:
Color/age/metallicity gradients of E galaxies
Short Name:
J/ApJ/766/109
Date:
21 Oct 2021
Publisher:
CDS
Description:
In order to understand the past merging history of elliptical galaxies, we studied the optical-near-infrared (NIR) color gradients of 204 elliptical galaxies. These galaxies are selected from the overlap region of the Sloan Digital Sky Survey (SDSS) Stripe 82 and the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). The use of optical and NIR data (g, r, and K) provides large wavelength baselines, and breaks the age-metallicity degeneracy, allowing us to derive age and metallicity gradients. The use of the deep SDSS Stripe 82 images makes it possible for us to examine how the color/age/metallicity gradients are related to merging features. We find that the optical-NIR color and the age/metallicity gradients of elliptical galaxies with tidal features are consistent with those of relaxed ellipticals, suggesting that the two populations underwent a similar merging history on average and that mixing of stars was more or less completed before the tidal features disappeared. Elliptical galaxies with dust features have steeper color gradients than the other two types, even after masking out dust features during the analysis, which can be due to a process involving wet merging. More importantly, we find that the scatter in the color/age/metallicity gradients of the relaxed and merging feature types decreases as their luminosities (or masses) increase at M>10^11.4^M_{sun}_ but stays large at lower luminosities. Mean metallicity gradients appear nearly constant over the explored mass range, but a possible flattening is observed at the massive end.
989. 15-color BATC photometry of Landolt SA95 field
ID:
ivo://CDS.VizieR/J/A+A/397/361
Title:
15-color BATC photometry of Landolt SA95 field
Short Name:
J/A+A/397/361
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, we present a set of photometric observations in 15 colors of stars in the Landolt SA95 field with the BATC (Beijing-Arizona-Taipei-Connecticut) system. The wavelengths covered by the system range from 300nm to 1000nm. Visual magnitudes of the stars studied in the field are from the 10th to 20th mag. The observational methodology and the data reduction procedures are described. The relationships between the BATC intermediate-band system and the Landolt UBVRI broad band system are obtained. A catalogue of the photometry has been produced which contains the spectral energy distributions (SEDs) of 3613 stars.
990. Color excess of SDSS quasars with DLA systems
ID:
ivo://CDS.VizieR/J/A+A/478/701
Title:
Color excess of SDSS quasars with DLA systems
Short Name:
J/A+A/478/701
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyzed the spectroscopic and photometric database of the 5th data release of the Sloan Digital Sky Survey (SDSS) to search for evidence of the quasar reddening produced by dust embedded in intervening damped Ly{alpha} (DLA) systems. From a list of 5164 quasars in the interval of emission redshift 2.25<=z_e_<=3.5 and SDSS spectra with signal-to-noise ratio SNR>~4, we built up an "absorption sample" of 248 QSOs with a single DLA system in the interval of absorption redshift 2.2<z_a_<=3.5 and a "pool" of 1959 control QSOs without DLA systems or strong metal systems. For each QSO of the absorption sample we extracted from the pool a subset of control QSOs that are closest in redshift and magnitude.