- ID:
- ivo://CDS.VizieR/J/MNRAS/477/L50
- Title:
- Structure of the Upper Scorpius association
- Short Name:
- J/MNRAS/477/L50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new proper motion data from recently published catalogs, we revisit the membership of previously identified members of the Upper Scorpius association. We confirmed 750 of them as cluster members based on the convergent point method, compute their kinematic parallaxes and combined them with Gaia parallaxes to investigate the 3D structure and geometry of the association using a robust covariance method. We find a mean distance of 146+/-3+/-6pc and show that the morphology of the association defined by the brightest (and most massive) stars yields a prolate ellipsoid with dimensions of 74x38x32pc^3^, while the faintest cluster members define a more elongated structure with dimensions of 98x24x18pc^3^. We suggest that the different properties of both populations is an imprint of the star formation history in this region.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/802/60
- Title:
- Structure of young stellar clusters. II.
- Short Name:
- J/ApJ/802/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the intrinsic stellar populations (estimated total numbers of OB and pre-main-sequence stars down to 0.1M_{sun}_) that are present in 17 massive star-forming regions (MSFRs) surveyed by the MYStIX project. The study is based on the catalog of >31000 MYStIX Probable Complex Members with both disk-bearing and disk-free populations, compensating for extinction, nebulosity, and crowding effects. Correction for observational sensitivities is made using the X-ray luminosity function and the near-infrared initial mass function --a correction that is often not made by infrared surveys of young stars. The resulting maps of the projected structure of the young stellar populations, in units of intrinsic stellar surface density, allow direct comparison between different regions. Several regions have multiple dense clumps, similar in size and density to the Orion Nebula Cluster. The highest projected density of ~34000 stars/pc2 is found in the core of the RCW 38 cluster. Histograms of surface density show different ranges of values in different regions, supporting the conclusion of Bressert et al. (B10; 2010MNRAS.409L..54B) that no universal surface-density threshold can distinguish between clustered and distributed star formation. However, a large component of the young stellar population of MSFRs resides in dense environments of 200-10000 stars/pc2 (including within the nearby Orion molecular clouds), and we find that there is no evidence for the B10 conclusion that such dense regions form an extreme "tail" of the distribution. Tables of intrinsic populations for these regions are used in our companion study of young cluster properties and evolution.
- ID:
- ivo://CDS.VizieR/VII/151
- Title:
- Structure Parameters of Galactic Globular Clusters
- Short Name:
- VII/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains observed and derived structure parameters for 154 galactic globular clusters, 7 dwarf spheroidal satellites of the Galaxy, and 6 globular clusters in the Fornax dwarf spheroids, respectively, in six different files. Files 1-3 (table1a, table1b, & table1c) list observed parameters, including cluster designation in order of right ascension, equatorial coordinates (B1950), apparent level of the cluster horizontal branch, reddening, subgiant branch color, limiting and core angular radii, ellipticities (only for table1b), integrated magnitude and central surface brightness. Files 4-6 (table2a, table2b, & table2c) contain positional and structural data derived from the observational data of table1. These include, for instance, galactic and galactocentric or Cartesian coordinates, heliocentric and galactocentric distances, or angular and projected linear distances, position angle, metallicity, limiting and core radii, central relaxation time scale, central mass density, central velocity dispersion, and central escape velocity. The references (all columns which label start by r_) are not available in electronic form.
- ID:
- ivo://CDS.VizieR/J/AJ/147/52
- Title:
- Structures in the Chandra Deep Field-South
- Short Name:
- J/AJ/147/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive structure detection analysis of the 0.3deg^2^ area of the MUSYC-ACES field, which covers the Chandra Deep Field-South (CDFS). Using a density-based clustering algorithm on the MUSYC and ACES photometric and spectroscopic catalogs, we find 62 overdense regions up to redshifts of 1, including clusters, groups, and filaments. We also present the detection of a relatively small void of ~10Mpc^2^ at z~0.53. All structures are confirmed using the DBSCAN method, including the detection of nine structures previously reported in the literature. We present a catalog of all structures present, including their central position, mean redshift, velocity dispersions, and classification based on their morphological and spectroscopic distributions. In particular, we find 13 galaxy clusters and 6 large groups/small clusters. Comparison of these massive structures with published XMM-Newton imaging (where available) shows that 80% of these structures are associated with diffuse, soft-band (0.4-1keV) X-ray emission, including 90% of all objects classified as clusters. The presence of soft-band X-ray emission in these massive structures (M_200_{>=}4.9x10^13^M_{sun}_) provides a strong independent confirmation of our methodology and classification scheme. In the closest two clusters identified (z<0.13) high-quality optical ur photometric sample contains 5522 galaxies imaging from the Deep2c field of the Garching-Bonn Deep Survey reveals the cD galaxies and demonstrates that they sit at the center of the detected X-ray emission. Nearly 60% of the clusters, groups, and filaments are detected in the known enhanced density regions of the CDFS at z=~0.13, 0.52, 0.68, and 0.73. Additionally, all of the clusters, bar the most distant, are found in these overdense redshift regions. Many of the clusters and groups exhibit signs of ongoing formation seen in their velocity distributions, position within the detected cosmic web, and in one case through the presence of tidally disrupted central galaxies exhibiting trails of stars. These results all provide strong support for hierarchical structure formation up to redshifts of 1.
18215. Structures in the GA region
- ID:
- ivo://CDS.VizieR/J/MNRAS/369/1131
- Title:
- Structures in the GA region
- Short Name:
- J/MNRAS/369/1131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To further our understanding of the Great Attractor (GA), we have undertaken a redshift survey using the 2dF on the AAT. Clusters and filaments in the GA region were targeted with 25 separate pointings resulting in approximately 2600 new redshifts. Targets included poorly studied X-ray clusters from the CIZA catalogue as well as the Cen-Crux and PKS 1343-601 clusters, both of which lie close to the classic GA centre. For nine clusters in the region, we report velocity distributions as well as virial and projected mass estimates. The virial mass of CIZA J1324.75736, now identified as a separate structure from the Cen-Crux cluster, is found to be ~3x10^14^M_{sun}_ in good agreement with the X-ray inferred mass. In the PKS 1343-601 field, five redshifts are measured of which four are new. An analysis of redshifts from this survey, in combination with those from the literature, reveals the dominant structure in the GA region to be a large filament, which appears to extend from Abell S0639 (l=281{deg}, b=+11{deg}) to (l~5{deg}, b~-50{deg}), encompassing the Cen-Crux, CIZA J1324.75736, Norma and Pavo II clusters. Behind the Norma Cluster at cz~15000km/s, the masses of four rich clusters are calculated. These clusters (Triangulum-Australis, Ara, CIZA J1514.64558 and CIZA J1410.44246) may contribute to a continued large- scale flow beyond the GA. The results of these observations will be incorporated into a subsequent analysis of the GA flow.
- ID:
- ivo://CDS.VizieR/J/ApJ/646/1009
- Title:
- Structures of dust in Perseus molecular cloud
- Short Name:
- J/ApJ/646/1009
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of 3.5deg^2^ of submillimeter continuum and extinction data of the Perseus molecular cloud. We identify 58 clumps in the submillimeter map, and we identify 39 structures (cores) and 11 associations of structures (super cores) in the extinction map. The cumulative mass distributions of the submillimeter clumps and extinction cores have steep slopes (alpha~2 and 1.5-2, respectively), steeper than the Salpeter initial mass function (IMF; alpha=1.35), while the distribution of extinction super cores has a shallow slope (alpha~1). Most of the submillimeter clumps are well fit by stable Bonnor-Ebert spheres with 10K<T<19K and 5.5<log_10_(Pext/k)<0.6. The clumps are found only in the highest column density regions (AV>5-7mag), although Bonnor-Ebert models suggest that we should have been able to detect them at lower column densities if they exist.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/80
- Title:
- STUDIES. III. SCUBA-2 450um gal. with MIPS & VLA obs.
- Short Name:
- J/ApJ/889/80
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We construct a SCUBA-2 450{mu}m map in the COSMOS field that covers an area of 300arcmin^2^ and reaches a 1{sigma} noise level of 0.65mJy in the deepest region. We extract 256 sources detected at 450{mu}m with signal-to-noise ratios >4.0 and analyze the physical properties of their multiwavelength counterparts. We find that most of the sources are at z<~3, with a median of z=1.79_-0.15_^+0.03^%. About 35_-25_^+32^% of our sources are classified as starburst galaxies based on their total star formation rates (SFRs) and stellar masses (M_*_). By fitting the far-infrared spectral energy distributions, we find that our 450{mu}m selected sample has a wide range of dust temperatures (20K<~T_d_<~60K), with a median of T_d_=38.3_-0.9_^+0.4^K. We do not find a redshift evolution in dust temperature for sources with L_IR_>10^12^L_{sun}_ at z<3. However, we find a moderate correlation where the dust temperature increases with the deviation from the SFR-M_*_ relation. The increase in dust temperature also correlates with optical morphology, which is consistent with merger-triggered starbursts in submillimeter galaxies. Our galaxies do not show the tight IRX-{beta}_UV_ correlation that has been observed in the local universe. We construct the infrared luminosity functions of our 450{mu}m sources and measure their comoving SFR densities (SFRDs). The contribution of the L_IR_>10^12^L_{sun}_ population to the SFRD rises dramatically from z=0 to 2 ({propto}(1+z)^3.9+/-1.1^) and dominates the total SFRD at z>~2.
- ID:
- ivo://CDS.VizieR/J/ApJ/865/103
- Title:
- STUDIES. II. NIR morphologies of submm galaxies
- Short Name:
- J/ApJ/865/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present structural parameters and morphological properties of faint 450{mu}m selected submillimeter galaxies (SMGs) from the JCMT Large Program, STUDIES, in the COSMOS-CANDELS region. Their properties are compared to an 850{mu}m selected and a matched star-forming samples. We investigate stellar structures of 169 faint 450{mu}m sources (S_450_=2.8-29.6mJy; S/N>4) at z<3 using HST near-infrared observations. Based on our spectral energy distribution fitting, half of such faint SMGs (L_IR_=10^11.65^+/-0.98^L_{sun}_) lie above the star formation rate (SFR)/stellar mass plane. The size-mass relation shows that these SMGs are generally similar to less-luminous star-forming galaxies selected by NUV-r versus r-J colors. Because of the intrinsic luminosity of the sample, their rest-frame optical emission is less extended than the 850{mu}m sources (S_850_>2mJy) and more extended than the star-forming galaxies in the same redshift range. For the stellar mass and SFR-matched sample at z~1 and z~2, the size differences are marginal between faint SMGs and the matched galaxies. Moreover, faint SMGs have similar Sersic indices and projected axis ratios as star-forming galaxies with the same stellar mass and SFR. Both SMGs and the matched galaxies show high fractions (~70%) of disturbed features at z~2, and the fractions depend on the SFRs. These suggest that their star formation activity is related to galaxy merging and the stellar structures of SMGs are similar to those of star-forming galaxies. We show that the depths of submillimeter surveys are approaching the lower luminosity end of star-forming galaxies, allowing us to detect galaxies on the main sequence.
- ID:
- ivo://CDS.VizieR/J/AZh/77/3
- Title:
- Studies of Bright Steep-Spectrum Radio Sources
- Short Name:
- J/AZh/77/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of studies of bright radio sources in the constellation Cetus are presented. More than 50% of the sources have radio spectral indices steeper than 0.9. Optical identifications have been determined for 35 sources. A large fraction of the radio sources are identified with weak blue galaxies. Given their spectral indices, it is likely that these objects have redshift z=0.4-1.0. More than 20% of the steep-spectrum sources do not have optical identifications and appear to be weak galaxies with z>2.
- ID:
- ivo://CDS.VizieR/J/AZh/80/704
- Title:
- Studies of classical barium stars
- Short Name:
- J/AZh/80/704
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundances of chemical elements in the atmospheres of seven classical barium stars are derived.