- ID:
- ivo://CDS.VizieR/J/A+A/601/A124
- Title:
- Clouds in SEDIGISM science demonstration field
- Short Name:
- J/A+A/601/A124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The origin and life-cycle of molecular clouds are still poorly constrained, despite their importance for understanding the evolution of the interstellar medium. Many large-scale surveys of the Galactic plane have been conducted recently, allowing for rapid progress in this field. Nevertheless, a sub-arcminute resolution global view of the large-scale distribution of molecular gas, from the diffuse medium to dense clouds and clumps, and of their relationship to the spiral structure, is still missing. We have carried out a systematic, homogeneous, spectroscopic survey of the inner Galactic plane, in order to complement the many continuum Galactic surveys available with crucial distance and gas-kinematic information. Our aim is to combine this data set with recent infrared to sub-millimetre surveys at similar angular resolutions. The SEDIGISM survey covers 78deg^2^ of the inner Galaxy (-60{deg}<l<+18{deg}, |b|<0.5{deg}) in the J=2-1 rotational transition of ^13^CO. This isotopologue of CO is less abundant than ^12^CO by factors up to 100. Therefore, its emission has low to moderate optical depths, and higher critical density, making it an ideal tracer of the cold, dense interstellar medium. The data have been observed with the SHFI single-pixel instrument at APEX. The observational setup covers the ^13^CO(2-1) and C^18^O(2-1) lines, plus several transitions from other molecules. The observations have been completed. Data reduction is in progress and the final data products will be made available in the near future. Here we give a detailed description of the survey and the dedicated data reduction pipeline. To illustrate the scientific potential of this survey, preliminary results based on a science demonstration field covering -20{deg}<l<-18.5{deg} are presented. Analysis of the ^13^CO(2-1) data in this field reveals compact clumps, diffuse clouds, and filamentary structures at a range of heliocentric distances. By combining our data with data in the (1-0) transition of CO isotopologues from the ThrUMMS survey, we are able to compute a 3D realization of the excitation temperature and optical depth in the interstellar medium. Ultimately, this survey will provide a detailed, global view of the inner Galactic interstellar medium at an unprecedented angular resolution of ~30".
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Search Results
92. Clusterix 2.0
- ID:
- ivo://CDS.VizieR/J/MNRAS/492/5811
- Title:
- Clusterix 2.0
- Short Name:
- J/MNRAS/492/5811
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Clusterix 2.0 is a web-based, Virtual Observatory compliant, interactive tool for the determination of membership probabilities in stellar clusters based on proper-motion data using a fully non-parametric method. In an area occupied by a cluster, the frequency function is made up of two contributions: cluster and field stars. The tool performs an empirical determination of the frequency functions from the vector point diagram without relying on any previous assumption about their profiles. Clusterix 2.0 allows us to search the appropriate spatial areas in an interactive way until an optimal separation of the two populations is obtained. Several parameters can be adjusted to make the calculation computationally feasible without interfering with the quality of the results. The system offers the possibility to query different catalogues, such as Gaia, or upload a user's own data. The results of the membership determination can be sent via Simple Application Messaging Protocol (SAMP) to Virtual Observatory (VO) tools such as Tool for OPerations on Catalogues And Tables (TOPCAT). We apply Clusterix 2.0 to several open clusters with different properties and environments to show the capabilities of the tool: an area of five degrees radius around NGC 2682 (M67), an old, well-known cluster; a young cluster NGC 2516 with a striking elongated structure extended up to four degrees; NGC 1750 and NGC 1758, a pair of partly overlapping clusters; the area of NGC 1817, where we confirm a little-known cluster, Juchert 23; and an area with many clusters, where we disentangle two overlapping clusters situated where only one was previously known: Ruprecht 26 and the new Clusterix 1.
- ID:
- ivo://CDS.VizieR/J/A+A/286/17
- Title:
- 21cm obs. of galaxies in Psc-Per Supercl.
- Short Name:
- J/A+A/286/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents the first results of a 21cm survey of newly discovered optically selected galaxies behind the Milky Way. We present 40 radial velocities of the new galaxies and 15 velocities of UGC and MCG galaxies in a region where the well known Pisces-Perseus-Supercluster (PPScl) is supposed to be veiled by galactic extinction (80deg<~l<~110deg). Twenty-four galaxies have radial velocities between 4000 and 6000 km/s that fit to the values usually accepted for the PPScl. We could pursue this supercluster at least to b=-5 deg around l=90 deg.
- ID:
- ivo://CDS.VizieR/J/ApJS/236/49
- Title:
- CO and 850um obs. of Planck Galactic cold clumps
- Short Name:
- J/ApJS/236/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to understand the initial conditions and early evolution of star formation in a wide range of Galactic environments, we carried out an investigation of 64 Planck Galactic cold clumps (PGCCs) in the second quadrant of the Milky Way. Using the ^13^CO and C^18^O J=1-0 lines and 850{mu}m continuum observations, we investigated cloud fragmentation and evolution associated with star formation. We extracted 468 clumps and 117 cores from the ^13^CO line and 850{mu}m continuum maps, respectively. We made use of the Bayesian distance calculator and derived the distances of all 64 PGCCs. We found that in general, the mass-size plane follows a relation of m~r^1.67^. At a given scale, the masses of our objects are around 1/10 of that of typical Galactic massive star-forming regions. Analysis of the clump and core masses, virial parameters, densities, and mass-size relation suggests that the PGCCs in our sample have a low core formation efficiency (~3.0%), and most PGCCs are likely low-mass star-forming candidates. Statistical study indicates that the 850{mu}m cores are more turbulent, more optically thick, and denser than the ^13^CO clumps for star formation candidates, suggesting that the 850{mu}m cores are likely more appropriate future star formation candidates than the ^13^CO clumps.
- ID:
- ivo://CDS.VizieR/J/ApJS/219/28
- Title:
- C^18^O/C^17^O ratios in the Galactic center
- Short Name:
- J/ApJS/219/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ^18^O/^17^O isotopic ratio of oxygen is a crucial measure of the secular enrichment of the interstellar medium by ejecta from high-mass versus intermediate-mass stars. So far, however, there is a lack of data, particularly from the Galactic center (GC) region. Therefore, we have mapped typical molecular clouds in this region in the J=1-0 lines of C^18^O and C^17^O with the Delingha 13.7m telescope (DLH). Complementary pointed observations toward selected positions throughout the GC region were obtained with the IRAM 30m and Mopra 22m telescopes. C^18^O/C^17^O abundance ratios reflecting the ^18^O/^17^O isotope ratios were obtained from integrated intensity ratios of C^18^O and C^17^O. For the first time, C^18^O/C^17^O abundance ratios are determined for Sgr C (V~-58km/s), Sgr D (V~80km/s), and the 1.3{deg} complex (V~80km/s). Through our mapping observations, abundance ratios are also obtained for Sgr A (~0 and ~50km/s component) and Sgr B2 (~60km/s), which are consistent with the results from previous single-point observations. Our frequency-corrected abundance ratios of the GC clouds range from 2.58+/-0.07 (Sgr D, V~80km/s, DLH) to 3.54+/-0.12 (Sgr A, ~50km/s). In addition, strong narrow components (line width less than 5km/s) from the foreground clouds are detected toward Sgr D (-18km/s), the 1.3{deg} complex (-18km/s), and M+5.3-0.3 (22km/s), with a larger abundance ratio around 4.0. Our results show a clear trend of lower C^18^O/C^17^O abundance ratios toward the GC region relative to molecular clouds in the Galactic disk. Furthermore, even inside the GC region, ratios appear not to be uniform. The low GC values are consistent with an inside-out formation scenario for our Galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/686/948
- Title:
- CO in extragalactic giant molecular clouds
- Short Name:
- J/ApJ/686/948
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use high spatial resolution observations of CO to systematically measure the resolved size-line width, luminosity-line width, luminosity-size, and mass-luminosity relations of GMCs in a variety of extragalactic systems. Although the data are heterogeneous, we analyze them in a consistent manner to remove the biases introduced by limited sensitivity and resolution, thus obtaining reliable sizes, velocity dispersions, and luminosities. We compare the results obtained in dwarf galaxies with those from the Local Group spiral galaxies. We find that extragalactic GMC properties measured across a wide range of environments are very much compatible with those in the Galaxy. The property that shows the largest variability is their resolved brightness temperature, although even that is similar to the average Galactic value in most sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/702/1472
- Title:
- Column densities for HI, AlIII, SiIV, CIV, OVI
- Short Name:
- J/ApJ/702/1472
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Column densities for HI, AlIII, SiIV, CIV, and OVI toward 109 stars and 30 extragalactic objects have been assembled to study the extensions of these species away from the Galactic plane into the Galactic halo. HI and AlIII mostly trace the warm neutral and warm ionized medium, respectively, while SiIV, CIV, and OVI trace a combination of warm photoionized and collisionally ionized plasmas. The much larger object sample compared to previous studies allows us to consider and correct for the effects of the sample bias that has affected earlier but smaller surveys of the gas distributions. The observations are compared to the predictions of the various models for the production of the transition temperature gas in the halo.
- ID:
- ivo://CDS.VizieR/J/ApJ/894/142
- Title:
- Column densities from HST/COS SiIV AGN sight lines
- Short Name:
- J/ApJ/894/142
- Date:
- 19 Jan 2022 13:10:08
- Publisher:
- CDS
- Description:
- We develop a kinematical model for the Milky Way SiIV-bearing gas to determine its density distribution and kinematics. This model is constrained by a column density line-shape sample extracted from the Hubble Space Telescope/Cosmic Origins Spectrograph archival data, which contains 186 active galactic nucleus sight lines. We find that the SiIV ion density distribution is dominated by an extended disk along the z-direction (above or below the midplane), i.e., n(z)=n_0_exp(-(z/z_0_)^0.82^), where z_0_ is the scale height of 6.3_-1.5_^+1.6^kpc (northern hemisphere) and 3.6_-0.9_^+1.0^kpc (southern hemisphere). The density distribution of the disk in the radial direction shows a sharp edge at 15-20kpc given by, n(r_XY_)=n_0_exp(-(r_XY_/r_0_)^3.36^), where r_0_~12.5+/-0.6kpc. The difference of density distributions over r_XY_ and z directions indicates that the warm gas traced by SiIV is mainly associated with disk processes (e.g., feedback or cycling gas) rather than accretion. We estimate the mass of the warm gas (within 50kpc) is log(M(50kpc)/M_{sun}_)~8.1 (assuming Z~0.5Z_{sun}_), and a 3{sigma} upper limit of log(M(250kpc)/M_{sun}_)~9.1 (excluding the Magellanic system). Kinematically, the warm gas disk is nearly co-rotating with the stellar disk at v_rot_=215+/-3km/s, which lags the midplane rotation by about 8km/s/kpc (within 5kpc). Meanwhile, we note that the warm gas in the northern hemisphere has significant accretion with vacc of 69+/-7km/s at 10kpc (an accretion rate of -0.60_-0.13_^+0.11^M_{sun}_/yr), while in the southern hemisphere, there is no measurable accretion, with an upper limit of 0.4M_{sun}_/yr.
- ID:
- ivo://CDS.VizieR/J/ApJ/722/395
- Title:
- Compact H I clouds from the GALFA-H I survey
- Short Name:
- J/ApJ/722/395
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic Arecibo L-band Feed Array H I (GALFA-H I) survey is mapping the entire Arecibo sky at 21 cm, over a velocity range of -700 to +700 km/s (LSR), at a velocity resolution of 0.18 km/s, and a spatial resolution of 3.5 arcmin. The unprecedented resolution and sensitivity of the GALFA-H I survey have resulted in the detection of numerous isolated, very compact H I clouds at low Galactic velocities, which are distinctly separated from the H I disk emission. In the limited area of ~4600 deg^2^ surveyed so far, we have detected 96 such compact clouds. The detected clouds are cold with a median T_k,max_ (the kinetic temperature in the case in which there is no non-thermal broadening) of 300 K. Moreover, these clouds are quite compact and faint, with median values of 5 arcmin in angular size, 0.75 K in peak brightness temperature, and 5x10^18^/cm2 in H I column density. Most of the clouds deviate from Galactic rotation at the 20-30 km/s level, and a significant fraction show evidence for a multiphase medium and velocity gradients. No counterparts for these clouds were found in other wave bands. From the modeling of spatial and velocity distributions of the whole compact cloud population, we find that the bulk of the compact clouds are related to the Galactic disk, and their distances are likely to be in the range of 0.1 to a few kpc. We discuss various possible scenarios for the formation and maintenance of this cloud population and its significance for Galactic interstellar medium studies.
- ID:
- ivo://CDS.VizieR/J/AJ/130/586
- Title:
- Compact radio sources in the galactic plane
- Short Name:
- J/AJ/130/586
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Archival data have been combined with recent observations of the Galactic plane using the Very Large Array to create new catalogs of compact centimetric radio sources. The 20cm source catalog covers a longitude range of -20{deg}<l<120{deg} the latitude coverage varies from +/-0.8{deg} to +/-2.7{deg}. The total survey area is about 331{deg}^2^; coverage is 90% complete at a flux density threshold of about 14mJy, and over 5000 sources are recorded. The 6cm catalog covers 43{deg}^2^ in the region -10{deg}<l<42{deg}, |b|<0.4{deg} to a 90% completeness threshold of 2.9mJy; over 2700 sources are found. Both surveys have an angular resolution of about 6". These catalogs provide a 30% (at 20cm) to 50% (at 6cm) increase in the number of high-reliability compact sources in the Galactic plane, as well as greatly improved astrometry, uniformity, and reliability; they should prove useful for comparison with new mid- and far-infrared surveys of the Milky Way.
