- ID:
- ivo://CDS.VizieR/J/MNRAS/416/178
- Title:
- 1.2-mm dust clumps with luminous water masers
- Short Name:
- J/MNRAS/416/178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a sensitive water maser search with the Australia Telescope Compact Array towards 267 1.2-mm dust clumps presented in the literature. We combine our new observations with previous water maser observations to extend our sample to 294 1.2-mm dust clumps, towards which we detect 165 distinct water maser sites towards 128 1.2-mm dust clumps. Within the fields of our observations, we additionally find four water masers with no apparent associated 1.2-mm dust continuum emission. Our overall detection rate of 44 per cent appears to vary as a function of Galactic longitude. We find that there is an excellent correspondence between the locations of the detected water masers with the peak of the target 1.2-mm dust clump sources. As expected from previous similar studies, the water masers are chiefly detected towards the bigger, brighter and more massive 1.2-mm dust clumps.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/118/191
- Title:
- Multitransition CS-study towards H2O masers
- Short Name:
- J/A+AS/118/191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed CS and C^34^S emission towards 33 H_2_O maser positions in the southern sky ({delta}<-28deg) using the SEST telescope. Most of the sources were selected also for their association with strong IRAS sources. CS(2-1) was detected in all sources, with the possible exception of two. Most sources were also mapped in the transitions CS(5-4) and C^34^S(2-1) and half of the sample also in CS(2-1). CS and C^34^S transitions J=2-1, J=3-2 J=5-4 were measured towards the centres of the clouds as determined from the mapping. CS and C^34^S transitions J=7-6 were measured in about a half dozen clouds. CO(1-0) was measured in most clouds in order to determine the kinetic temperatures. The CS column densities were calculated using the LTE approximation. All measurements were also analyzed using a spherical LVG model. We present the observational data and the results of this analysis.
- ID:
- ivo://CDS.VizieR/J/ApJ/856/152
- Title:
- New star clusters in the central plane region
- Short Name:
- J/ApJ/856/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of new star clusters in the central plane region (|l|<30{deg} and |b|<6{deg}) of the Milky Way. In order to overcome the extinction problem and the spatial limit of previous surveys, we use the Wide-field Infrared Survey Explorer (WISE) data to find clusters. We also use other infrared survey data in the archive for additional analysis. We find 923 new clusters, of which 202 clusters are embedded clusters. These clusters are concentrated toward the Galactic plane and show a symmetric distribution with respect to the Galactic latitude. The embedded clusters show a stronger concentration to the Galactic plane than the nonembedded clusters. The new clusters are found more in the first Galactic quadrant, while previously known clusters are found more in the fourth Galactic quadrant. The spatial distribution of the combined sample of known clusters and new clusters is approximately symmetric with respect to the Galactic longitude. We estimate reddenings, distances, and relative ages of the 15 class A clusters using theoretical isochrones. Ten of them are relatively old (age >800Myr) and five are young (age ~4Myr).
- ID:
- ivo://CDS.VizieR/J/A+A/606/A52
- Title:
- NGC7538-IRS1 THz water maser
- Short Name:
- J/A+A/606/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of massive stars (M>10M_{sun}_, L>10^3^L_{sun}_) is still not well understood. Accumulating a large amount of mass infalling within a single entity in spite of radiation pressure is possible if, among several other conditions, enough thermal energy is released. Despite numerous water line observations, over a broad range of energies, with the Herschel Space Observatory, in most of the sources observations were not able to trace the emission from the hot core around the newly forming protostellar object. We want to probe the physical conditions and water abundance in the inner layers of the host protostellar object NGC7538-IRS1 using a highly excited H_2_O line. Water maser models predict that several THz water masers should be detectable in these objects. We therefore aim to detect for the first time the o-H_2_O 8_2,7_-7_3,4_ line in a star forming region, which model calculations predict to show maser action. We present SOFIA observations of the o-H_2_O 8_2,7_-7_3,4_ line at 1296.41106GHz and a 6_16_-5_23_ 22GHz e-MERLIN map of the region (first-ever 22GHz images made after the e-MERLIN upgrade). In order to be able to constrain the nature of the emission - thermal or maser - we use near-simultaneous observations of the 22GHz water maser performed with the Elsberg radiotelescope and e-MERLIN. A thermal water model using the RATRAN radiative transfer code is presented based on HIFI pointed observations. Molecular water abundances are derived for the hot core. The of the o-H_2_O 8_2,7_-7_3,4_ line is detected toward NGC7538-IRS1 with one feature at the source velocity (-57.7km/s) and another one at -48.4km/s. We propose that the emission at the source velocity is consistent with thermal excitation and is excited in the innermost part of the IRS1a massive protostellar object's closest circumstellar environment. The other emission is very likely the first detection of a water THz maser line, pumped by shocks due to IRS1b outflow, in a star-forming region. Assuming thermal excitation of the THz line, the water abundance in NGC7538-IRS1's hot core is estimated to be 5.2x10^-5^ with respect to H_2_.
- ID:
- ivo://CDS.VizieR/J/ApJ/581/325
- Title:
- NGC 2071 water masers
- Short Name:
- J/ApJ/581/325
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have mapped the water maser emission associated with the infrared centers IRS 1 and IRS 3 of the NGC 2071 IR star-forming region at four epochs over ~4 months with the Very Long Baseline Array. We detected 269 maser features with ~1km/s line widths and measured 30 proper motions. In each infrared center, the water maser emission appears to trace parts of a protostellar disk and collimated outflow.
- ID:
- ivo://CDS.VizieR/J/ApJ/669/446
- Title:
- Observations of SiO masers
- Short Name:
- J/ApJ/669/446
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of SiO millimeter line observations of a sample of known SiO maser sources covering a wide dust temperature range. A cold part of the sample was selected from the SiO maser sources found in our recent SiO maser survey of cold dusty objects. The aim of the present research is to investigate the causes of the correlation between infrared colors and SiO maser intensity ratios among different transition lines. In particular, the correlation between infrared colors and SiO maser intensity ratio among the J=1-0 v=1, 2, and 3 lines are our main concern in this paper. We observed in total 75 SiO maser sources with the Nobeyama 45m telescope quasi-simultaneously in the SiO J=1-0 v=0, 1, 2, 3, 4 and J=2-1 v=1, 2 lines. We also observed the sample in the ^29^SiO J=1-0 v=0 and J=2-1 v=0 lines, ^30^SiO J=1-0 v=0 line, and the H_2_O 61,6-52,3 line.
- ID:
- ivo://CDS.VizieR/J/A+A/394/975
- Title:
- OH 5-cm line survey in late-type stars
- Short Name:
- J/A+A/394/975
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken a comprehensive search for 5-cm excited OH maser emission from evolved stars representative of various stages of late stellar evolution. Observed sources were selected from known 18-cm OH sources. This survey was conducted with the 100-m Effelsberg telescope, at 6.0GHz in Sep 2000, to achieve high signal to noise ratio observations and a sensitivity limit of about 0.05 to 0.1Jy. A total of 65 stellar sources were searched for both main line and satellite line emission. We confirm the previous detection of 5 cm OH in Vy 2-2, do not confirm emission from NML-Cyg and do not report any other new detection within the above sensitivity limit. The number of observed sources is 67.
- ID:
- ivo://CDS.VizieR/J/A+AS/111/237
- Title:
- OH detections from circumstellar shells
- Short Name:
- J/A+AS/111/237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identified 240 accessible circumstellar shells with water and/or SiO masers, and used the Arecibo and Nancay radio telescopes to search for mainline OH emission from them. Our targets are often Mira variables without previously known mainline masers. This search results in 89 detections, of which 77 are new.
- ID:
- ivo://CDS.VizieR/J/A+AS/137/43
- Title:
- OH/H2O masers database
- Short Name:
- J/A+AS/137/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 3 contains VLA spectra and positions for OH and H2O maser spots in 74 star-forming regions mapped by Forster and Caswell (1989A&A...213..339F). Galactic coordinates are given, followed by offset positions of the 22GHz continuum peak (HII) if detected, and the flux, velocity and positions of OH and H_2_O maser spots mapped in that field.
- ID:
- ivo://CDS.VizieR/J/A+A/327/755
- Title:
- OH maser emission from IRAS sources
- Short Name:
- J/A+A/327/755
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A high-sensitivity search for water maser emission at 22.2 GHz has been performed on a sample of 91 IRAS point sources at high-latitudes. The aim of the survey is to verify if these clouds are capable of star formation as indicated by the presence of water masers. The sample is based on the recent work of Magnani et al. (1995ApJS...96..159M) who have identified 192 infrared objects from the IRAS Faint Source Survey possibly associated with translucent clouds at galactic latitudes |b|>=30{deg}. These IRAS sources have far-infrared colours typical of young stellar objects and pre-main-sequence stars and thus provide a starting list for further studies about their actual nature. H_2_O maser emission is a good diagnostic of the presence of dense gas and of recent star formation. We did not find water maser emission at a level of 0.2-0.5Jy (3{sigma}) in any of the 91 objects. The negative result indicates that these high-latitude sources do not represent potential sites of star formation, consistent with the fact that most high-latitude molecular clouds do not appear gravitationally bound.
