- ID:
- ivo://CDS.VizieR/J/ApJS/182/143
- Title:
- SCUPOL Legacy polarimetry of SCUBA
- Short Name:
- J/ApJS/182/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- SCUPOL, the polarimeter for SCUBA on the James Clerk Maxwell Telescope, was the most prolific thermal imaging polarimeter built to date. Between 1997 and 2005, observations of 104 regions were made at 850um in the mapping mode. The instrument has produced ~50 refereed journal publications, and that number is still growing. We have systematically re-reduced all imaging polarimetry made in the standard "jiggle-map" mode from the SCUBA archive (2800+ individual observations) to produce a catalog of SCUPOL images and tables. We present the results of our analysis with figures and data tables produced for all 83 regions where significant polarization was detected. In addition, the reduced data cubes and data tables can be accessed online. In many cases, the data included in this paper have been previously published elsewhere. However, this publication includes unpublished data sets, in whole or in part, toward 39 regions, including cores in Rho Ophiuchus, Orion's OMC-2 region, several young stellar objects, and the galaxy M87.
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- ID:
- ivo://CDS.VizieR/J/A+A/577/A30
- Title:
- SDC335.579-0.292 6, 8, 23 and 25GHz images
- Short Name:
- J/A+A/577/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent ALMA observations identified one of the most massive star-forming cores yet observed in the Milky Way: SDC335-MM1, within the infrared dark cloud SDC335.579-0.292. Along with an accompanying core MM2, SDC335 appears to be in the early stages of its star formation process. We aim to constrain the properties of the stars forming within these two massive millimetre sources. Observations of SDC335 at 6, 8, 23 and 25GHz were made with the Australia Telescope Compact Array.We report the results of these continuum measurements, which combined with archival data, allow us to build and analyse the spectral energy distributions (SEDs) of the compact sources in SDC335.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A142
- Title:
- SDC G335.579-0.292 ALMA images and datacubes
- Short Name:
- J/A+A/645/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The infrared dark cloud (IRDC) SDC335.579-0.292 (hereafter, SDC335) is a massive (~5000 solar masses) star-forming cloud which has been found to be globally collapsing towards one of the most massive star forming cores in the Galaxy, which is located at its centre. SDC335 is known to host three high-mass protostellar objects at early stages of their evolution and archival ALMA Cycle 0 data (at ~5 arcsecond resolution) indicate the presence of at least one molecular outflow in the region detected in HNC. Observations of molecular outflows from massive protostellar objects allow us to estimate the accretion rates of the protostars as well as to assess the disruptive impact that stars have on their natal clouds during their formation. The aim of this work is to identify and analyse the properties of the protostellar-driven molecular outflows within SDC335 and use these outflows to help refine the properties of the young massive protostars in this cloud. We imaged the molecular outflows in SDC335 using new data from the Australia Telescope Compact Array (ATCA) of SiO and Class I CH_3_OH maser emission (at a resolution of ~3 arcsecond) alongside} observations of four CO transitions made with the Atacama Pathfinder EXperiment (APEX) and archival Atacama Large Millimeter/submillimeter Array (ALMA) CO, 13CO (~1 arcsecond), and HNC data. We introduced a generalised argument to constrain outflow inclination angles based on observed outflow properties. We then used the properties of each outflow to infer the accretion rates on the protostellar sources driving them. These accretion properties allowed us to deduce the evolutionary characteristics of the sources. Shock-tracing SiO emission and CH_3_OH Class I maser emission allowed us to locate regions of interaction between the outflows and material infalling to the central region via the filamentary arms of SDC335.
- ID:
- ivo://CDS.VizieR/J/A+A/561/A83
- Title:
- SDC13 infrared dark clouds spectra
- Short Name:
- J/A+A/561/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Formation of stars is now believed to be tightly linked to the dynamical evolution of interstellar filaments in which they form. In this paper we analyze the density structure and kinematics of a small network of infrared dark filaments, SDC13, observed in both dust continuum and molecular line emission with the IRAM 30m telescope. These observations reveal the presence of 18 compact sources amongst which the two most massive, MM1 and MM2, are located at the intersection point of the parsec-long filaments. The dense gas velocity and velocity dispersion observed along these filaments show smooth, strongly correlated, gradients. We discuss the origin of the SDC13 velocity field in the context of filament longitudinal collapse. We show that the collapse timescale of the SDC13 filaments (from 1Myr to 4Myr depending on the model parameters) is consistent with the presence of Class I sources in them, and argue that, on top of bringing more material to the centre of the system, collapse could generate additional kinematic support against local fragmentation, helping the formation of starless super-Jeans cores. SDC13 is composed of three Spitzer Dark Clouds from the Peretto & Fuller (2009, cat J/A+A/505/405) catalogue (SDC13.174-0.07, SDC13.158-0.073, SDC13.194-0.073).
- ID:
- ivo://CDS.VizieR/J/A+A/613/A11
- Title:
- SDC13 NH_3_(1,1) and NH_3_(2,2) datacubes
- Short Name:
- J/A+A/613/A11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Converging networks of interstellar filaments, that is hubs, have been recently linked to the formation of stellar clusters and massive stars. Understanding the relationship between the evolution of these systems and the formation of cores and stars inside them is at the heart of current star formation research. The goal is to study the kinematic and density structure of the SDC13 prototypical hub at high angular resolution to determine what drives its evolution and fragmentation. We have mapped SDC13, a ~1000M_{sun}_ infrared dark hub, in NH_3_(1,1) and NH_3_(2,2) emission lines, with both the Jansky Very Large Array and Green Bank Telescope. The high angular resolution achieved in the combined dataset allowed us to probe scales down to 0.07pc. After fitting the ammonia lines, we computed the integrated intensities, centroid velocities and line widths, along with gas temperatures and H_2_ column densities. The mass-per-unit-lengths of all four hub filaments are thermally super- critical, consistent with the presence of tens of gravitationally bound cores identified along them. These cores exhibit a regular separation of ~0.37+/-0.16pc suggesting gravitational instabilities running along these super-critical filaments are responsible for their fragmentation. The observed local increase of the dense gas velocity dispersion towards starless cores is believed to be a consequence of such fragmentation process. Using energy conservation arguments, we estimate that the gravitational to kinetic energy conversion efficiency in the SDC13 cores is ~35%. We see velocity gradient peaks towards ~63% of cores as expected during the early stages of filament fragmentation. Another clear observational signature is the presence of the most massive cores at the filaments' junction, where the velocity dispersion is largest. We interpret this as the result of the hub morphology generating the largest acceleration gradients near the hub centre. We propose a scenario for the evolution of the SDC13 hub in which filaments first form as post-shock structures in a supersonic turbulent flow. As a result of the turbulent energy dissipation in the shock, the dense gas within the filaments is initially mostly subsonic. Then gravity takes over and starts shaping the evolution of the hub, both fragmenting filaments and pulling the gas towards the centre of the gravitational well. By doing so, gravitational energy is converted into kinetic energy in both local (cores) and global (hub centre) potential well minima. Furthermore, the generation of larger gravitational acceleration gradients at the filament junctions promotes the formation of more massive cores.
- ID:
- ivo://CDS.VizieR/J/ApJ/809/146
- Title:
- SDSS-DR8 isolated low-mass galaxies
- Short Name:
- J/ApJ/809/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the baryon content of low-mass galaxies selected from the Sloan Digital Sky Survey (SDSS DR8), focusing on galaxies in isolated environments where the complicating physics of galaxy-galaxy interactions are minimized. We measure neutral hydrogen (HI) gas masses and line widths for 148 isolated galaxies with stellar mass between 10^7^ and 10^9.5^M_{sun}_. We compare isolated low-mass galaxies to more massive galaxies and galaxies in denser environments by remeasuring HI emission lines from the Arecibo Legacy Fast ALFA survey 40% data release. All isolated low-mass galaxies either have large atomic gas fractions or large atomic gas fractions cannot be ruled out via their upper limits. We measure a median atomic gas fraction of f_gas_=0.81+/-0.13 for our isolated low-mass sample with no systems below 0.30. At all stellar masses, the correlations between galaxy radius, baryonic mass, and velocity width are not significantly affected by environment. Finally, we estimate a median baryon to total dynamical mass fraction of f_baryon,disk_=0.15+/-0.17. We also estimate two different median baryon to halo mass fractions using the results of semi-analytic models (f_baryon,disk_=0.04+/-0.06) and abundance matching (f_baryon,halo_=0.04+/-0.02). Baryon fractions estimated directly using HI observations appear independent of environment and maximum circular velocity, while baryon fractions estimated using abundance matching show a significant depletion of baryons at low maximum circular velocities.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A53
- Title:
- Search for H2O2 in Orion
- Short Name:
- J/A+A/583/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundance of key molecules determines the level of cooling that is necessary for the formation of stars and planetary systems. In this context, one needs to understand the details of the time dependent oxygen chemistry, leading to the formation of molecular oxygen and water. We aim to determine the degree of correlation between the occurrence of O2 and HOOH (hydrogen peroxide) in star-forming molecular clouds. We first detected O2 and HOOH in the rho Ophiuchi cloud (core A), we now search for HOOH in Orion Molecular Cloud OMC A, where O2 has also been detected. We mapped a 3x3arcmin^2^ region around Orion H_2_-Peak 1 with the Atacama Pathfinder Experiment (APEX). In addition to several maps in two transitions of HOOH, viz. 219.17GHz and 251.91GHz, we obtained single-point spectra for another three transitions towards the position of maximum emission. Line emission at the appropriate LSR-velocity (Local Standard of Rest) and at the level of greater or equal to 4{sigma} was found for two transitions, with lower S/N (2.8-3.5{sigma}) for another two transitions, whereas for the remaining transition, only an upper limit was obtained. The emitting region, offset 18arcsec south of H_2_-Peak 1, appeared point-like in our observations with APEX. Conclusions: The extremely high spectral line density in Orion makes the identification of HOOH much more difficult than in rho Oph A. As a result of having to consider the possible contamination by other molecules, we left the current detection status undecided.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A85
- Title:
- Search for thioacetamide CH3CSNH2 in the ISM
- Short Name:
- J/A+A/658/A85
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- One of the biggest unsolved mysteries of modern astrochemistry is understanding chemical formation pathways in the interstellar medium (ISM) and circumstellar environments (CSEs). The detections (or even nondetections) of molecules composed of low-abundance atomic species (such as S, P, Si, and Mg) may help to constrain chemical pathways. Thioacetamide (CH_3_CSNH_2_) is the sulfur analog to acetemide (CH_3_CONH_2_) and it is a viable candidate to search for in astronomical environments - specifically toward regions where other S-bearing molecules have been found and, if possible, that also contain a detection of CH_3_CONH_2_. If detected, it would not only continue to expand the view of molecular complexity in astronomical environments, but also help to better elucidate the possible formation pathways of these types of species in these environments. Our aim is to expand the frequency range of the measured rotational spectrum of CH_3_CSNH_2_ beyond 150GHz and then to use those measurements to extend the search for this species in the ISM. The new laboratory measurements and expanded search cover more parameter space for determining under what conditions CH_3_CSNH_2_ may be detected, leading to possible constraints on the formation of large S-bearing molecules found in the ISM. The rotational spectrum of CH_3_CSNH_2_ was investigated up to 650GHz. Using the newly refined spectrum of CH_3_CSNH_2_, as well as additional spectroscopic data on the chemically related species CH_3_CONH_2_, a variety of astronomical sources were searched including data from the following large surveys: Prebiotic Interstellar Molecule Survey (PRIMOS) conducted with the Green Bank Telescope (GBT); Exploring molecular complexity with ALMA (EMoCA) conducted with the Atacama Large Millimeter/submillimeter Array (ALMA); and Astrochemical Surveys At IRAM (ASAI) conducted with the Institut de Radioastronomie Millim'etrique (IRAM) 30m Telescope. A total of 1428 transitions from the v_t_=0 state with maximum values J=47 and K_a_=20 in the range up to 330GHz, and J=95 and K_a_=20 in the range from 400-660GHz were assigned. We also assigned 321 transitions from the v_t=1 state with the maximum values J=35 and K_a_=9 up to 330GHz. We achieved a final fit with a root-mean-square deviation of 43.4kHz that contains 2035 measured lines from our study and the literature for v_t_=0 and v_t_=1 states of A and E symmetries. The final fit is based on the rho-axis- method (RAM) Hamiltonian model that includes 40 parameters. An astronomical search for CH_3_CSNH_2_ was conducted based on all the new spectroscopic data. No transitions of CH_3_CSNH_2_ were detected toward any of the sources contained in our survey. Using the appropriate telescope and physical parameters for each astronomical source, upper limits to the column densities were found for CH_3_CSNH_2_ toward each source.
- ID:
- ivo://CDS.VizieR/J/A+A/594/A26
- Title:
- Second Planck Catalogue of Compact Sources (PCCS2)
- Short Name:
- J/A+A/594/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Second Planck Catalogue of Compact Sources is a list of discrete objects detected in single-frequency maps from the full duration of the Planck mission and supersedes previous versions. It consists of compact sources, both Galactic and extragalactic, detected over the entire sky. Compact sources detected in the lower frequency channels are assigned to the PCCS2, while at higher frequencies they are assigned to one of two subcatalogues, the PCCS2 or PCCS2E, depending on their location on the sky. The first of these (PCCS2) covers most of the sky and allows the user to produce subsamples at higher reliabilities than the target 80% integral reliability of the catalogue. The second (PCCS2E) contains sources detected in sky regions where the diffuse emission makes it difficult to quantify the reliability of the detections. Both the PCCS2 and PCCS2E include polarization measurements, in the form of polarized flux densities, or upper limits, and orientation angles for all seven polarization-sensitive Planck channels. The improved data-processing of the full-mission maps and their reduced noise levels allow us to increase the number of objects in the catalogue, improving its completeness for the target 80% reliability as compared with the previous versions, the PCCS and the Early Release Compact Source Catalogue (ERCSC).
- ID:
- ivo://CDS.VizieR/J/A+A/619/A166
- Title:
- SEDIGISM, kinematics of ATLASGAL filaments
- Short Name:
- J/A+A/619/A166
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Analyzing the kinematics of filamentary molecular clouds is a crucial step toward understanding their role in the star formation process. Therefore, we study the kinematics of 283 filament candidates in the inner Galaxy, that were previously identified in the ATLASGAL dust continuum data. The ^13^CO(2-1) and C^18^O(2-1) data of the SEDIGISM survey (Structure, Excitation, and Dynamics of the Inner Galactic Inter Stellar Medium) allows us to analyze the kinematics of these targets and to determine their physical properties at a resolution of 30-arcsec and 0.25km/s. To do so, we developed an automated algorithm to identify all velocity components along the line-of-sight correlated with the ATLASGAL dust emission, and derive size, mass, and kinematic properties for all velocity components. We find two-third of the filament candidates are coherent structures in position-position-velocity space. The remaining candidates appear to be the result of a superposition of two or three filamentary structures along the line-of-sight. At the resolution of the data, on average the filaments are in agreement with Plummer-like radial density profiles with a power-law exponent of p~=1.5+/-0.5, indicating that they are typically embedded in a molecular cloud and do not have a well-defined outer radius. Also, we find a correlation between the observed mass per unit length and the velocity dispersion of the filament of m{prop.to}{sigma}_v_^2^. We show that this relation can be explained by a virial balance between self-gravity and pressure. Another possible explanation could be radial collapse of the filament, where we can exclude infall motions close to the free-fall velocity.
