Class I and Class II methanol masers in high-mass star-forming regions

Fontani, F.; Cesaroni, R.; Furuya, Ray S.

doi:10.1051/0004-6361/200913679

Cited by 103 publications

(108 citation statements)

References 34 publications

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“…5). The 6.7 GHz Class II methanol maser has also been detected here by Fontani et al (2010). The radiatively excited Class II masers are associated with hot molecular cores, UCH ii regions and near-IR sources associated with massive young stellar objects, while the collisionally pumped Class I maser sources are generally offset and believed to form at the interfaces between outflows and ambient material or expansion of H ii regions.…”

Section: S7supporting

confidence: 59%

Dust and gas environment of the young embedded cluster IRAS 18511+0146

Vig

Testi

Walmsley

et al. 2017

A&A

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Context. Since massive and intermediate mass stars form in clusters, a comparative investigation of the environments of the young embedded cluster members can reveal significant information about the conditions under which stars form and evolve. Aims. IRAS 18511+0146 is a young embedded (proto)cluster located at 3.5 kpc surrounding what appears to be an intermediate mass protostar. In this paper, we investigate the nature of cluster members (two of which are believed to be the most massive and luminous) using imaging and spectroscopy in the near and mid-infrared. In particular, we examine the three brightest mid-infrared objects and two among these are believed to be most massive ones driving the luminosity of this region. Methods. Near-infrared spectroscopy of nine objects (bright in K bands) towards IRAS 18511+0146 has been carried out. Several cluster members have also been investigated in the mid-infrared using spectroscopic and imaging with VISIR on the VLT. Far-infrared images from the Herschel Hi-GAL survey have been used to construct the column density and temperature maps of the region. Results. The brightest point-like object associated with IRAS 18511+0146 is referred to as S7 in the present work (designated UGPS J185337.88+015030.5 in the UKIRT Galactic Plane survey). S7 is likely the most luminous object in the cluster as it is bright at all wavelengths ranging from the near-infrared to millimetre. Seven of the nine objects show rising spectral energy distributions (SED) in the near-infrared, with four objects showing Br-γ emission. Three members: S7, S10 (also UGPS J185338.37+015015.3) and S11 (also UGPS J185338.72+015013.5) are bright in mid-infrared with diffuse emission being detected in the vicinity of S11 in PAH bands. Silicate absorption is detected towards these three objects, with an absorption maximum between 9.6 and 9.7 µm, large optical depths (1.8 − 3.2), and profile widths of 1.6 − 2.1 µm. The silicate profiles of S7 and S10 are similar, in contrast to S11 (which has the largest width and optical depth). The cold dust emission peaks at S7, with temperature at 26 K and column density N(H 2 )∼ 7 × 10 22 cm −2 . The bolometric luminosity of IRAS 18511 region is L∼ 1.8 × 10 4 L ⊙ . S7 is the main contributor to the bolometric luminosity, with L (S7) 10 4 L ⊙ . Conclusions. S7 is a high mass protostellar object with ionised stellar winds, evident from the correlation between radio and bolometric luminosity as well as the asymmetric Br-γ profile. The differences in silicate profiles of S7 and S11 could be due to different radiation environment as we believe the former to be more massive and in an earlier phase than the latter.

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Section: S7supporting

confidence: 59%

Dust and gas environment of the young embedded cluster IRAS 18511+0146

Vig

Testi

Walmsley

et al. 2017

A&A

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“…The most important progress of the 6.7 GHz methanol maser discovery is the Methanol Multibeam (MMB) Survey of the entire Galactic plane (e.g. Green et al 2009Green et al , 2010Green et al , 2012Caswell et al 2011). Fontani et al (2010 searched for the 6.7 GHz methanol masers toward 296 massive star forming regions, and detected 55 masers, 12 of which are new.…”

Section: 7 Ghz Methanol Masersmentioning

confidence: 99%

The observed spiral structure of the Milky Way

Hou

Han

2014

A&A

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Context. The spiral structure of the Milky Way is not yet well determined. The keys to understanding this structure are to increase the number of reliable spiral tracers and to determine their distances as accurately as possible. HII regions, giant molecular clouds (GMCs), and 6.7 GHz methanol masers are closely related to high mass star formation, and hence they are excellent spiral tracers. The distances for many of them have been determined in the literature with trigonometric, photometric, and/or kinematic methods. Aims. We update the catalogs of Galactic HII regions, GMCs, and 6.7 GHz methanol masers, and then outline the spiral structure of the Milky Way. Methods. We collected data for more than 2500 known HII regions, 1300 GMCs, and 900 6.7 GHz methanol masers. If the photometric or trigonometric distance was not yet available, we determined the kinematic distance using a Galaxy rotation curve with the current IAU standard, R 0 = 8.5 kpc and Θ 0 = 220 km s −1 , and the most recent updated values of R 0 = 8.3 kpc and Θ 0 = 239 km s −1 , after velocities of tracers are modified with the adopted solar motions. With the weight factors based on the excitation parameters of HII regions or the masses of GMCs, we get the distributions of these spiral tracers.Results. The distribution of tracers shows at least four segments of arms in the first Galactic quadrant, and three segments in the fourth quadrant. The Perseus Arm and the Local Arm are also delineated by many bright HII regions. The arm segments traced by massive star forming regions and GMCs are able to match the HI arms in the outer Galaxy. We found that the models of three-arm and four-arm logarithmic spirals are able to connect most spiral tracers. A model of polynomial-logarithmic spirals is also proposed, which not only delineates the tracer distribution, but also matches the observed tangential directions.

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“…However, there were no systematic searches for the 95 GHz maser transition until Kalenskii et al (1994). We have combined the results of all previous 95 GHz methanol maser single-dish searches that are reported in Kalenskii et al (1994), Val'tts et al (1995, 2000, Ellingsen (2005), Kalenskii et al (2006), Fontani et al (2010), Chen et al (2011Chen et al ( , 2012Chen et al ( , 2013a, and Gan et al (2013) to produce a catalog of all maser sources in this transition.…”

Section: Searches For 95 Ghz Methanol Masers: 1994-2016mentioning

confidence: 99%

A New 95 GHz Methanol Maser Catalog. I. Data

Yang

Chen

et al. 2017

ApJS

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The Purple Mountain Observatory 13.7 m radio telescope has been used to search for 95 GHz (8 0 -7 1 A + ) class I methanol masers toward 1020 Bolocam Galactic Plane Survey (BGPS) sources, leading to 213 detections. We have compared the line width of the methanol and HCO + thermal emission in all of the methanol detections, and on that basis, we find that 205 of the 213 detections are very likely to be masers. This corresponds to an overall detection rate of 95 GHz methanol masers toward our BGPS sample of 20%. Of the 205 detected masers, 144 (70%) are new discoveries. Combining our results with those of previous 95 GHz methanol maser searches, a total of 481 95 GHz methanol masers are now known. We have compiled a catalog listing the locations and properties of all known 95 GHz methanol masers.

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Class I and Class II methanol masers in high-mass star-forming regions

Cited by 103 publications

References 34 publications

Dust and gas environment of the young embedded cluster IRAS 18511+0146

Dust and gas environment of the young embedded cluster IRAS 18511+0146

The observed spiral structure of the Milky Way

A New 95 GHz Methanol Maser Catalog. I. Data

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