- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3461
- Title:
- 6.7-GHz methanol masers-dust associations
- Short Name:
- J/MNRAS/446/3461
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of 870{mu}m continuum observations, using the Large APEX Bolometer Camera, towards 77 class-II, 6.7-GHz methanol masers identified by the Methanol MultiBeam (MMB) survey to map the thermal emission from cool dust towards these objects. These data complement a study of 630 methanol masers associated with compact dense clumps identified from the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) survey. Compact dust emission is detected towards 70 sources, which implies a dust-association rate of 99 per cent for the full MMB catalogue. Evaluation of the derived dust and maser properties leads us to conclude that the combined sample represents a single population tracing the same phenomenon. We find median clump masses of a few 10^3^M_{sun}_ and that all but a handful of sources satisfy the mass-size criterion required for massive star formation. This study provides the strongest evidence of the almost ubiquitous association of methanol masers with massive, star-forming clumps. The fraction of methanol-maser associated clumps is a factor of ~2 lower in the outer Galaxy than the inner Galaxy, possibly a result of the lower metallicity environment of the former. We find no difference in the clump-mass and maser-luminosity distributions of the inner and outer Galaxy. The maser-pumping and clump formation mechanisms are therefore likely to be relatively invariant to Galactic location. Finally, we use the ratio of maser luminosity and clump mass to investigate the hypothesis that the maser luminosity is a good indicator of the evolutionary stage of the embedded source, however, we find no evidence to support this.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/753/50
- Title:
- 6.7GHz methanol masers. I. NH_3_ lines
- Short Name:
- J/ApJ/753/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Methanol masers at 6.7GHz are known to be tracers of high-mass star formation in our Galaxy. In this paper, we study the large-scale physical conditions in the star-forming clumps/cores associated with 6.7GHz methanol masers using observations of the (1,1), (2,2), and (3,3) inversion transitions of ammonia with the Effelsberg telescope. The gas kinetic temperature is found to be higher than in infrared dark clouds, highlighting the relatively evolved nature of the maser sources. Other than a weak correlation between maser luminosity and the ammonia line width, we do not find any differences between low- and high-luminosity methanol masers.
- ID:
- ivo://CDS.VizieR/J/ApJ/763/2
- Title:
- 95GHz methanol masers in molecular outflows
- Short Name:
- J/ApJ/763/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed a sample of 288 molecular outflow sources including 123 high-mass and 165 low-mass sources in order to search for class I methanol masers at the 95GHz transition and to investigate the relationship between outflow characteristics and class I methanol maser emission with the Purple Mountain Observatory 13.7m radio telescope. Our survey detected 62 sources with 95GHz methanol masers above a 3{sigma} detection limit, which includes 47 high-mass sources and 15 low-mass sources. Therefore, the detection rate is 38% for high-mass outflow sources and 9% for low-mass outflow sources, suggesting that class I methanol masers are relatively easily excited in high-mass sources. There are 37 newly detected 95GHz methanol masers (including 27 high-mass and 10 low-mass sources), 19 of which are newly identified (i.e., first identification) class I methanol masers (including 13 high-mass and 6 low-mass sources). A statistical analysis of the distributions of maser detections with the outflow parameters reveals that the maser detection efficiency increases with the outflow properties (e.g., mass, momentum, kinetic energy, mechanical luminosity of outflows, etc.). Systematic investigations of the relationships between the intrinsic luminosity of methanol masers and the outflow properties (including mass, momentum, kinetic energy, bolometric luminosity, and mass-loss rate of the central stellar sources) indicate a positive correlation. This further supports the theory that class I methanol masers are collisionally pumped and associated with shocks when outflows interact with the surrounding ambient medium.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/219
- Title:
- 6.7 GHz methanol masers observations
- Short Name:
- J/MNRAS/474/219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results of 6.7GHz methanol maser monitoring of 139 star-forming sites with the Torun 32-m radio telescope from 2009 June to 2013 February. The targets were observed at least once a month, with higher cadences of two to four measurements per week for circumpolar objects. Nearly 80 per cent of the sources display variability greater than 10 per cent on a time-scale between a week and a few years, but about three quarters of the sample have only one to three spectral features that vary significantly. Irregular intensity fluctuation is the dominant type of variability and only nine objects show evidence for cyclic variations with periods of 120 to 416d. Synchronized and anticorrelated variations of maser features are detected in four sources with a disc-like morphology. Rapid and high-amplitude bursts of individual features are seen on three to five occasions in five sources. Long (>50d to 20 months) lasting bursts are observed mostly for individual or groups of features in 19 sources and only one source experienced a remarkable global flare. A few flaring features display a strong anticorrelation between intensity and line-width that is expected for unsaturated amplification. There is a weak anticorrelation between the maser feature luminosity and variability measure, i.e. maser features with low luminosity tend to be more variable than those with high luminosity. The analysis of the spectral energy distribution and continuum radio emission reveals that the variability of the maser features increases when the bolometric luminosity and Lyman flux of the exciting object decreases. Our results support the concept of a major role for infrared pumping photons in triggering outburst activity of maser emission.
- ID:
- ivo://CDS.VizieR/J/ApJS/245/12
- Title:
- 6.7GHz methanol masers & RRLs in MSX regions
- Short Name:
- J/ApJS/245/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a systematic survey of a 6.7GHz Class II methanol maser toward a sample of 448 sources selected from the Red Midcourse Space Experiment Source catalog. These sample sources are composed of high-mass star-forming region (HMSFR) candidates and have been studied as tracers of HMSFRs, such as water masers or radio continuum emission of ultracompact HII region. The survey was conducted using the Shanghai Tianma Radio Telescope. Through the observations, we simultaneously studied the 4.7 and 6.0GHz excited-state interstellar hydroxyl (OH) maser lines and 10 hydrogen radio recombination lines (RRLs) in the C band. In total, we detected 6.7GHz methanol masers and RRLs from 102 and 116 sources, respectively. In addition, 4, 3, and 10 sources exhibit OH masers at 4765.56, 6030.75, and 6035.09MHz transitions, respectively. Through the survey, we identified four new 6.7GHz methanol maser sources and three new excited-state OH maser sources (one at 4750MHz and two at 6035MHz). The statistical analysis demonstrated that there is a positive correlation of luminosity between 6.7GHz methanol masers and RRLs. A good correlation of integrated luminosity between radio continuum emission and the 6.7GHz methanol masers is presented with respect to the RRL emission sources. The average of the integrated luminosities of the RRLs in the sources with 6.7GHz masers is greater than those without the 6.7GHz masers; similarly, the average of integrated luminosities of the 6.7GHz methanol masers in the sources with RRLs is greater than those without the RRLs. Moreover, we found that the averages of the emission measure and electron temperature of HII regions associated with 6.7GHz methanol masers are larger than those without the 6.7GHz methanol masers. This suggests that the masers are most likely produced in high gas density and luminous regions with brighter RRLs and higher radio continuum emission.
- ID:
- ivo://CDS.VizieR/J/A+A/403/1095
- Title:
- 6.7GHz methanol masers survey of low-mass YSO
- Short Name:
- J/A+A/403/1095
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a search for 6.7-GHz methanol masers toward low-mass young stellar objects (YSOs) and (pre)protostellar condensations with the Australia Telescope Compact Array (ATCA). Our sample consisted of 13 class 0 protostars and 44 class I YSOs as well as 66 (pre)protostellar condensations. A single detection was obtained toward NGC 2024: FIR4 in the Orion B region. This is the first detection of a 6.7-GHz methanol maser in Orion. The nature of FIR4 has been a subject of debate with some evidence suggesting that it is a very cold high-mass (pre)protostellar condensation and others arguing that it is a low-mass YSO. The discovery of a methanol maser associated with this source is inconsistent with both of these hypotheses and we suggest that FIR4 probably harbours an intermediate- or high-mass YSO.
- ID:
- ivo://CDS.VizieR/VIII/96
- Title:
- 6-GHz methanol multibeam maser catalogue
- Short Name:
- VIII/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a Galactic plane survey of methanol masers at 6668 MHz using a seven-beam receiver on the Parkes telescope, refered to as MX observations. Paper I provides sensitive unbiased coverage of a large region around the Galactic Centre. Details are given for 183 methanol maser sites in the longitude range 345{deg} through the Galactic Centre to 6{deg}. Within 6{deg} of the Galactic Centre, we found 88 maser sites, of which more than half (48) are new discoveries. The masers are confined to a narrow Galactic latitude range, indicative of many sources at the Galactic Centre distance and beyond, and confined to a thin disc population; there is no high-latitude population that might be ascribed to the Galactic bulge. Paper II spans the longitude range 6{deg} to 20{deg}. We report the detection of 119 maser sources, of which 42 are new discoveries. Paper III covers the longitude range 330{deg}-345{deg}, yielding 198 masers, of which more than 40 per cent are new discoveries. Paper IV span the longitude range 186{deg}-330{deg}. We report 207 maser detections, 89 new to the survey. This completes the southern sky part of the methanol multibeam survey and includes a large proportion of new sources, 43 per cent. We also include results from blind observations of the Orion-Monoceros star-forming region, formally outside the latitude range of the methanol multibeam survey; only the four previously known methanol emitting sites were detected, of which we present new positions and spectra for masers at Orion A (south) and Orion B, obtained with the Multi-Element Radio Linked Interferometer Network (MERLIN) array.
- ID:
- ivo://CDS.VizieR/J/A+A/413/233
- Title:
- 12.2 GHz methanol survey
- Short Name:
- J/A+A/413/233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of 12.2GHz methanol maser survey done with the Torun 32 meter radio telescope. We examined 261 star forming sites, known as containing 6.7GHz maser emission sources. The survey resulted in 49 sources with maser line detection, with 21 previously unknown emissions. All detected 12.2GHz masers have been observed at 6.7GHz transition. Only one 12.2GHz source has no 6.7GHz counterpart. We compared basic spectral line properties at both transitions. In a few cases we observed absorption features and emitting counterparts in the other monitored frequency, at the same velocity.
- ID:
- ivo://CDS.VizieR/J/A+A/418/103
- Title:
- 86GHz SiO maser survey in the Inner Galaxy
- Short Name:
- J/A+A/418/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a compilation and study of DENIS, 2MASS, ISOGAL, MSX and IRAS 1-25 microns photometry for a sample of 441 late-type stars in the inner Galaxy, which we previously searched for 86GHz SiO maser emission (Messineo et al., 2002, Cat. <J/A+A/393/115>). The comparison of the DENIS and 2MASS J and Ks magnitudes shows that most of the SiO targets are indeed variable stars. The MSX colours and the IRAS [12]-[25] colour of our SiO targets are consistent with those of Mira type stars with dust silicate feature at 9.7 microns feature in emission, indicating only a moderate mass-loss rate.
- ID:
- ivo://CDS.VizieR/J/A+A/393/115
- Title:
- 86GHz SiO maser survey of late-type stars
- Short Name:
- J/A+A/393/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 86GHz (v=1, J=2-1) SiO maser line observations with the IRAM 30-m telescope of a sample of 444 late-type stars in the Inner Galaxy (-4{deg}<l<+30{deg}). These stars were selected on basis of their infrared magnitudes and colours from the ISOGAL and MSX catalogues. SiO maser emission was detected in 271 sources, and their line-of-sight velocities indicate that the stars are located in the Inner Galaxy. These new detections double the number of line-of-sight velocities available from previous SiO and OH maser observations in the area covered by our survey and are, together with other samples of e.g. OH/IR stars, useful for kinematic studies of the central parts of the Galaxy.
