- ID:
- ivo://CDS.VizieR/J/ApJ/702/1615
- Title:
- CH_3_OH maser survey of EGOs
- Short Name:
- J/ApJ/702/1615
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a high angular resolution Very Large Array (VLA) Class I 44GHz and Class II 6.7GHz CH_3_OH maser survey of a sample of ~20 massive young stellar object (MYSO) outflow candidates selected on the basis of extended 4.5um emission in Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire images. These 4.5um selected candidates are referred to as extended green objects (EGOs), for the common coding of this band as green in three-color Infrared Array Camera images. The detection rate of 6.7GHz Class II CH_3_OH masers, which are associated exclusively with massive YSOs, toward EGOs is >~64% - nearly double the detection rate of surveys using other MYSO selection criteria. The detection rate of Class I 44GHz CH_3_OH masers, which trace molecular outflows, is ~89% toward EGOs associated with 6.7GHz CH_3_OH masers.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/227/10
- Title:
- CH_3_OH & OH line emission from Galactic center
- Short Name:
- J/ApJS/227/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Class I methanol masers are collisionally pumped and are generally correlated with outflows in star-forming sites in the Galaxy. Using the Very Large Array in its A-array configuration, we present a spectral line survey to identify methanol J=4_-1_->3_0_E emission at 36.169GHz. Over 900 pointings were used to cover a region 66'x13' along the inner Galactic plane. A shallow survey of OH at 1612, 1665, 1667, and 1720MHz was also carried out over the area covered by our methanol survey. We provide a catalog of 2240 methanol masers with narrow line-widths of ~1km/s, spatial resolutions of ~0.14"x0.05", and rms noises ~20mJy/beam per channel. Lower limits on the brightness temperature range from 27000 to 10000000K, showing that the emission is of non-thermal origin. We also provide a list of 23 OH (1612), 14 OH (1665), 5 OH (1667), and 5 OH (1720MHz) masers. The origin of such a large number of methanol masers is not clear. Many methanol masers appear to be associated with infrared dark clouds, though it appears unlikely that the entire population of these masers traces the early phase of star formation in the Galactic center.
- 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.
- 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.