- ID:
- ivo://CDS.VizieR/J/A+A/644/A102
- Title:
- CH3SC(O)H observed line frequencies and strengths
- Short Name:
- J/A+A/644/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- S-methyl thioformate CH_3_SC(O)H is a monosulfur derivative of methyl formate, a relatively abundant component of the interstellar medium (ISM). S-methyl thioformate being, thermodynamically,the most stable isomer, it can be reasonably proposed for detection in the ISM. This work aims to experimentally study and theoretically analyze the ground and first torsional excited states for CH_3_SC(O)H in a large spectral range for astrophysical use. S-methyl thioformate was synthesized as a result of a reaction of methyl mercaptan with acetic-formic anhydride. The millimeter-wave spectrum was then recorded for the first time from 150 to 660GHz with the solid-state-based spectrometer at Lille. A set of 3545 lines is determined and combined with 54 previously measured lines in the microwave region, belonging to ground state vt=0 as well as 1391 transitions in the first excited state of torsion v18=1. Some 164 lines were also assigned to vt18=2 for the A-species. A global fit was performed using the BELGI-Cs code taking into account the large splitting of A and E lines due to methyl internal rotation motion with a relatively low barrier, V3=127.4846(15)cm^-1^. Using our spectroscopy work, a deep search of S-methyl thioformate was carried out in the IRAM 30m and ALMA data of different high-mass star-forming regions (Orion KL and Sgr B2). We derived an upper limit to the CH_3_SC(O)H column density in these regions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/639/L13
- Title:
- 4C 41.17 IRAM/NOEMA data cubes
- Short Name:
- J/A+A/639/L13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new, spatially resolved [CI]1-0, [CI]2-1, CO(7-6), and dust continuum observations of 4C 41.17 at z=3.8. This is one of the best-studied radio galaxies in this epoch and is arguably the best candidate of jet-triggered star formation at high redshift currently known in the literature. 4C 41.17 shows a narrow ridge of dust continuum extending over 15kpc near the radio jet axis. Line emission is found within the galaxy in the region with signatures of positive feedback. Using the [CI]1-0 line as a molecular gas tracer, and multifrequency observations of the far-infrared dust heated by star formation, we find a total gas mass of 7.6x10^10^M_{sun}_, which is somewhat greater than that previously found from CO(4-3). The gas mass surface density of 10^3^M_{sun}_/yr/pc^2^ and the star formation rate surface density of 10M_{sun}_/yr/kpc^2^ were derived over the 12 kpc8 kpc area, where signatures of positive feedback have previously been found. These densities are comparable to those in other populations of massive, dusty star-forming galaxies in this redshift range, suggesting that the jet does not currently enhance the efficiency with which stars form from the gas. This is consistent with expectations from simulations, whereby radio jets may facilitate the onset of star formation in galaxies without boosting its efficiency over longer timescales, in particular after the jet has broken out of the interstellar medium, as is the case in 4C 41.17. The release includes Gaussian line fits to the [CI]1-0, [CI]2-1, and CO(7-6) emission lines in the radio galaxy 4C 41.17 at z=3.8, as well as the interferometric data cubes.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1262
- Title:
- Circular polarization images at 15GHz of AGN jets
- Short Name:
- J/AJ/131/1262
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report first-epoch circular polarization results for 133 active galactic nuclei in the MOJAVE (Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments) program to monitor the structure and polarization of a flux-limited sample of extragalactic radio jets with the VLBA at 15GHz. We found strong circular polarization (0.3%) in approximately 15% of our sample. The circular polarization was usually associated with jet cores; however, we did find a few strong jet components to be circularly polarized.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A67
- Title:
- Circumstellar envelopes CO photodissociation
- Short Name:
- J/A+A/606/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Carbon monoxide is the most abundant molecule after H_2_ and is important for chemistry in circumstellar envelopes around late-type stars. The size of the envelope is important when modelling low-J transition lines and deriving mass-loss rates from such lines. Now that ALMA is coming to full power the extent of the CO emitting region can be measured directly for nearby asymptotic giant branch (AGB) stars. In parallel, it has become obvious in the past few years that the strength of the interstellar radiation field (ISRF) can have a significant impact on the interpretation of the emission lines. In this paper an update and extension of the classical Mamon et al. (1988ApJ...328..797M) paper is presented; these authors provided the CO abundance profile, described by two parameters, as a function of mass-loss rate and expansion velocity. Following recent work an improved numerical method and updated H_2_ and CO shielding functions are used and a larger grid is calculated that covers more parameter space, including the strength of the ISRF. The effect of changing the photodissociation radius on the low-J CO line intensities is illustrated in two cases.
- ID:
- ivo://CDS.VizieR/J/ApJS/68/715
- Title:
- Clark Lake 30.9MHz survey
- Short Name:
- J/ApJS/68/715
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic plane has been mapped at 30.9 MHz with the Clark Lake TPT telescope giving unprecedented resolution for such a low frequency. The synthetized beam is 13.0'x11.1' at the zenith. Contour maps and a source list are presented for the regions 350deg<l<59deg, 84deg<l<97deg, and 133deg<l<250deg, with |b|<2deg-3deg. The source list contains integrated flux densities and positions for 702 discrete emission regions. Sensitivity is confusion-limited and varies from ~ 5Jy/beam in the inner Galaxy to ~ 1-2Jy/beam toward the outer Galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/359/1498
- Title:
- Class I and class II methanol masers
- Short Name:
- J/MNRAS/359/1498
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Australia Telescope National Facility Mopra millimetre telescope has been used to search for 95.1-GHz class I methanol masers towards 62 6.6-GHz class II methanol masers. A total of 26 95.1-GHz masers were detected, 18 of these being new discoveries. Combining the results of this search with observations reported in the literature, a near complete sample of 66 6.6-GHz class II methanol masers has been searched in the 95.1-GHz transition, with detections towards 38 per cent (25 detections; not all of the sources studied in this paper qualify for the complete sample, and some of the sources in the sample were not observed in the present observations).
- ID:
- ivo://CDS.VizieR/J/AZh/89/611
- Title:
- Class I methanol maser catalog
- Short Name:
- J/AZh/89/611
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have revised the Astro Space Center catalog of Class I methanol masers detected in starforming regions (MMI/SFR), mainly at 44GHz, and created a new electronic version of the catalog. Currently, the catalog contains 206 objects, selected from publications through 2011 inclusive. The data from the survey of Chen et al. (2011, Cat. J/ApJS/196/9), performed specifically for objects EGO, which form a new specific catalog, are not included. The MMI/SFR objects were identified with emission and absorption objects in the near IR, detected during the MSX and Spitzer space missions. Seventy-one percent of Class I methanol masers that emit at 44GHz and fall within the Galactic longitude range surveyed by Spitzer (GLIMPSE) are identified with Spitzer Dark Clouds (SDCs), and 42% with Extended Green Objects (EGOs). It is possible that Class I methanol masers arise in isolated, self-gravitating clumps, such as SDCs, at certain stages of their evolution. A sample of SDCs is proposed as a new target list for Class I methanol maser searches. A detailed statistical analysis was carried out, taking into account the characteristics of the regions of MMI/SFR formation presented in the catalog.
- ID:
- ivo://CDS.VizieR/VIII/72
- Title:
- CLASS survey of radio sources
- Short Name:
- VIII/72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cosmic Lens All-Sky Survey (CLASS) is an international collaborative program aimed at obtaining high-resolution radio images of over 10000 flat-spectrum radio sources in order to create the largest and best studied statistical sample of radio-loud gravitationally lensed systems. CLASS is aimed at identifying lenses where multiple images are formed from compact flat-spectrum radio sources, which should be easily identifiable in the radio maps (Browne et al., 2003MNRAS.341...13B). In four observing ``seasons'' from 1994-1999, CLASS has observed 13832 radio sources. When combined with the JVAS survey, the CLASS sample contains over 16,000 images. Using the GB6 and NVSS surveys, a complete statistical subset of 11685 sources has been constructed. These were selected from the NVSS 20-cm (Condon et al., 1998, Cat. <VIII/65>) and GB6 6-cm (Gregory et al., 1996, Cat. <VIII/40>) catalogues by the selection criteria: declination >0deg, |b|<10deg, S(6cm)>=30mJy, and spectral index between 6 and 20cm flatter than -0.5 (S proportional to frequency^+alpha^). The remaining sources were selected using earlier versions of these catalogues or with slightly relaxed versions of these criteria.
- ID:
- ivo://CDS.VizieR/J/A+A/656/A154
- Title:
- ClG 0217+70 radio images
- Short Name:
- J/A+A/656/A154
- Date:
- 21 Mar 2022 09:15:55
- Publisher:
- CDS
- Description:
- Megaparsec-scale radio sources in the form of halos and relics are often detected in dynamically disturbed galaxy clusters. Although they are associated with merger-induced turbulence and shocks, respectively, their formation is not fully understood. Aims. We aim to identify the mechanisms responsible for particle acceleration and magnetic field amplification in the halo and relics of the galaxy cluster ClG 0217+70. We observed ClG 0217+70 with LOFAR at 141MHz and with VLA at 1.5GHz, and we combined these observations with VLA 1.4GHz archival data to study the morphological and spectral properties of the diffuse sources.We added Chandra archival data to examine the thermal and non-thermal properties of the halo. Our LOFAR and VLA data confirm the presence of a giant radio halo in the cluster centre and multiple relics in the outskirts. The radio and X-ray emission from the halo are correlated, implying a tight relation between the thermal and non-thermal components. The diuse radio structure in the south-east, with a projected size of 3.5Mpc, is the most extended radio relic detected to date. The spectral index across the relic width steepens towards the cluster centre, suggesting electron ageing in the post-shock regions. The shock Mach numbers for the relics derived from the spectral index map range between 2.0 and 3.2. However, the integrated spectral indices lead to increasingly high Mach numbers for the relics farther from the cluster centre. This discrepancy could be because the relation between injection and integrated spectra does not hold for distant shocks, suggesting that the cooling time for the radioemitting electrons is longer than the crossing time of the shocks. The variations in the surface brightness of the relics and the low Mach numbers imply that the radio-emitting electrons are re-accelerated from fossil plasma that could originate in active galactic nuclei.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A10
- Title:
- 3C295 LOFAR, MERLIN and VLA images
- Short Name:
- J/A+A/658/A10
- Date:
- 02 Feb 2022 13:43:44
- Publisher:
- CDS
- Description:
- 3C295 is a bright, compact steep spectrum source with a well-studied integrated radio spectral energy distribution (SED) from 132MHz to 15GHz. However, spatially resolved spectral studies have been limited due to a lack of high resolution images at low radio frequencies. These frequencies are crucial for measuring absorption processes, and anchoring the overall spectral modelling of the radio SED. In this paper, we use International LOw-Frequency ARray (LOFAR) Telescope (ILT) observations of 3C295 to study its spatially resolved spectral properties with sub-arcsecond resolution at 132MHz. Combining our new 132MHz observation with archival data at 1.6GHz, 4.8GHz, and 15GHz, we are able to carryout a resolved radio spectral analysis. The spectral properties of the hotspots provides evidence for low frequency flattening. In contrast, the spectral shape across the lobes is consistent with a Jaffe-Perola spectral ageing model. Usingthe integrated spectral information for each component, we then fitted low-frequency absorption models to the hotspots,finding that both free-free absorption and synchrotron self-absorption models provide a better fit to the data than a standard power law. Although we can say there is low-frequency absorption present in the hot spots of 3C295, future observations with the Low Band Antenna of the ILT at 55MHz may allow us to distinguish the type of absorption.
