- ID:
- ivo://CDS.VizieR/J/A+A/563/A97
- Title:
- IRAM 30m reduced spectra of 59 sources
- Short Name:
- J/A+A/563/A97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Understanding the chemical evolution of young (high-mass) star-forming regions is a central topic in star formation research. Chemistry is employed as a unique tool 1) to investigate the underlying physical processes and 2) to characterize the evolution of the chemical composition. With these aims in mind, we observed a sample of 59 high-mass star-forming regions at different evolutionary stages varying from the early starless phase of infrared dark clouds to high-mass protostellar objects to hot molecular cores and, finally, ultra-compact HII regions at 1mm and 3mm with the IRAM 30m telescope. We determined their large-scale chemical abundances and found that the chemical composition evolves along with the evolutionary stages.
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- ID:
- ivo://CDS.VizieR/J/A+A/544/L7
- Title:
- IRAS 16293-2422 ALMA maps
- Short Name:
- J/A+A/544/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We focus on the kinematical properties of a proto-binary to study the infall and rotation of gas toward its two protostellar components. We present ALMA Science Verification observations with high-spectral resolution of IRAS 16293-2422 at 220.2GHz. The wealth of molecular lines in this source and the very high spectral resolution offered by ALMA allow us to study the gas kinematics with unprecedented detail.
- ID:
- ivo://CDS.VizieR/J/A+A/422/141
- Title:
- IRAS 08211-4158 cluster IR photometry
- Short Name:
- J/A+A/422/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the astrometry and near infrared photometry (H, K, L, M) of the cluster associated with the star forming region IRAS 08211-4158 in the Vela Molecular Clouds. The observations were carried out with SofI at NTT (H, K) and ISAAC at VLT (L, M ).
- ID:
- ivo://CDS.VizieR/J/ApJ/897/53
- Title:
- IR dark clouds parameters in molecular clouds
- Short Name:
- J/ApJ/897/53
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- Ever since their discovery, infrared dark clouds (IRDCs) are generally considered to be the sites just at the onset of high-mass (HM) star formation. In recent years, it has been realized that not all IRDCs harbor HM young stellar objects (YSOs). Only those IRDCs satisfying a certain mass-size criterion, or equivalently above a certain threshold density, are found to contain HMYSOs. In all cases, IRDCs provide ideal conditions for the formation of stellar clusters. In this paper, we study the massive stellar content of IRDCs to readdress the relation between IRDCs and HM star formation. For this purpose, we have identified all IRDCs associated with a sample of 12 Galactic molecular clouds (MCs). The selected MCs have been the target of a systematic search for YSOs in an earlier study. The cataloged positions of YSOs have been used to search all YSOs embedded in each identified IRDC. In total, we have found 834 YSOs in 128 IRDCs. The sample of IRDCs have mean surface densities of 319M{odot}/pc^2^, mean mass of 1062M{odot}, and a mass function power-law slope -1.8, which are similar to the corresponding properties for the full sample of IRDCs and resulting physical properties in previous studies. We find that all those IRDCs containing at least one intermediate to HM young star satisfy the often-used mass-size criterion for forming HM stars. However, not all IRDCs satisfying the mass-size criterion contain HM stars. We find that the often-used mass-size criterion corresponds to 35% probability of an IRDC forming a massive star. Twenty-five (20%) of the IRDCs are potential sites of stellar clusters of mass more than 100M{odot}.
- ID:
- ivo://CDS.VizieR/J/A+A/503/859
- Title:
- IRDC 19175-4 and IRDC 19175-5 turbulence maps
- Short Name:
- J/A+A/503/859
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aims is to characterizing the gas and dust properties prior to and in the neighborhood of active intermediate- to high-mass star formation. Two Infrared Dark Clouds (IRDCs), IRDC 19175-4 and IRDC 19175-5, that are located in the vicinity of the luminous massive star-forming region IRAS 19175+1357, but that remain absorption features up to 70um wavelength, were observed with the Plateau de Bure Interferometer in the 3.23mm dust continuum as well as the N2H^+^(1-0) and ^13^CS(2-1) line emission.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A79
- Title:
- IRDC APEX/SABOCA observations
- Short Name:
- J/A+A/559/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared-dark clouds (IRDCs) harbor the early phases of cluster and high-mass star formation and are comprised of cold (~20K), dense (n>10^4^cm^-3^) gas. The spectral energy distribution (SED) of IRDCs is dominated by the far-infrared and millimeter wavelength regime, and our initial Herschel study examined IRDCs at the peak of the SED with high angular resolution. Here we present a follow-up study using the SABOCA instrument on APEX which delivers 7.8" angular resolution at 350{mu}m, matching the resolution we achieved with Herschel/PACS, and allowing us to characterize substructure on ~0.1pc scales. Our sample of 11 nearby IRDCs are a mix of filamentary and clumpy morphologies, and the filamentary clouds show significant hierarchical structure, while the clumpy IRDCs exhibit little hierarchical structure. All IRDCs, regardless of morphology, have about 14% of their total mass in small scale core-like structures which roughly follow a trend of constant volume density over all size scales. Out of the 89 protostellar cores we identified in this sample with Herschel, we recover 40 of the brightest and re-fit their SEDs and find their properties agree fairly well with our previous estimates (<T>~19K). We detect a new population of "cold cores" which have no 70{mu}m counterpart, but are 100 and 160{mu}m-bright, with colder temperatures (<T>~16K). This latter population, along with SABOCA-only detections, are predominantly low-mass objects, but their evolutionary diagnostics are consistent with the earliest starless or prestellar phase of cores in IRDCs.
- ID:
- ivo://CDS.VizieR/J/A+A/529/A161
- Title:
- IRDC core G11.11-0.12P1 methanol maps
- Short Name:
- J/A+A/529/A161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study with the Plateau de Bure Interferometer of a core in the archetypal filamentary IRDC G11.11-0.12 of a few arcsecond resolution to determine its physical and chemical structures. The data consist of continuum and line observations covering the C^34^S 2-1 line and the methanol 2_k_-1_k_ v_t_=0 lines at 3mm and the methanol 5_k_-4_k_ v_t_=0 lines at1mm. Our observations show extended emission in the continuum at 1 and 3mm. The methanol 2-1 emission has three maxima extending over a 1pc scale (when merged with single-dish short-spacing observations); one of the maxima is spatially coincident with the continuum emission. The fitting results show an enhanced methanol fractional abundance at the central peak with respect to the other two peaks, where it decreases by about an order of magnitude. Wings in the CH_3_OH 2-1 spectra, and CH_3_OH abundance enhancements point to the presence of an outflow in the east-west direction. In addition, we find a gradient of ~4km/s in the same direction, which we interpret as being produced by an outflow(s)-cloud interaction.
- ID:
- ivo://CDS.VizieR/J/MNRAS/399/1506
- Title:
- IRDC cores in SCUBA Legacy Catalogue
- Short Name:
- J/MNRAS/399/1506
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an investigation of candidate infrared dark cloud (IRDC) cores as identified by Simon et al. (2006, Cat. J/ApJ/639/227) located within the Submillimetre Common User Bolometer Array (SCUBA) Legacy Catalogue. After applying a uniform noise cut to the catalogue data, we identify 154 IRDC cores that were detected at 850um and 51 cores that were not. We derive column densities for each core from their 8um extinction and find that the IRDCs detected at 850um have higher column densities (a mean of 1.7x10^22^cm^-2^) compared to those cores not detected at 850um (a mean of 1.0x10^22^cm-2).
289. 4 IRDC data cubes
- ID:
- ivo://CDS.VizieR/J/A+A/571/A53
- Title:
- 4 IRDC data cubes
- Short Name:
- J/A+A/571/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- How molecular clouds form out of the atomic phase and what the relative fractions of carbon are in the ionized, atomic, and molecular phase are questions at the heart of cloud and star formation. We want to understand the kinematic processes of gas flows during the formation of molecular clouds. In addition to that, we aim at determining the abundance ratios of carbon in its various gas phases from the ionized to the molecular form. Using multiple observatories from Herschel and SOFIA to APEX and the IRAM 30m telescope, we mapped the ionized and atomic carbon as well as carbon monoxide ([CII] at 1900GHz, [CI] at 492GHz, and C^18^O(2-1) at 220GHz) at high spatial resolution (12"-25") in four young massive infrared dark clouds (IRDCs).
- ID:
- ivo://CDS.VizieR/J/A+A/606/A133
- Title:
- IRDC G035.39-00.33 NH3 and CCS data cubes
- Short Name:
- J/A+A/606/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared dark clouds represent the earliest stages of high-mass star formation. Detailed observations of their physical conditions on all physical scales are required to improve our understanding of their role in fueling star formation. We investigate the large-scale structure of the IRDC G035.39-00.33, probing the dense gas with the classical ammonia thermometer. This allows us to put reliable constraints on the temperature of the extended, pc-scale dense gas reservoir and to probe the magnitude of its non-thermal motions. Available far-infrared observations can be used in tandem with the observed ammonia emission to estimate the total gas mass contained in G035.39-00.33. We identify a main velocity component as a prominent filament, manifested as an ammonia emission intensity ridge spanning more than 6 pc, consistent with the previous studies on the Northern part of the cloud. A number of additional line-of-sight components are found, and a large-scale linear velocity gradient of ~0.2km/s/pc is found along the ridge of the IRDC. In contrast to the dust temperature map, an ammonia-derived kinetic temperature map, presented for the entirety of the cloud, reveals local temperature enhancements towards the massive protostellar cores. We show that without properly accounting for the line of sight contamination, the dust temperature is 2-3K larger than the gas temperature measured with NH_3_. While both the large-scale kinematics and temperature structure are consistent with that of starless dark filaments, the kinetic gas temperature profile on smaller scales is suggestive of tracing the heating mechanism coincident with the locations of massive protostellar cores.
