The Medicina survey of methanol masers at 6.7 GHz

Slysh, V. I.; Вальтц, И. Е.; Kalenskii, S. V.; Voronkov, M. A.; Palagi, F.; Tofani, G.; Catarzi, M.

doi:10.1051/aas:1999127

Cited by 96 publications

(140 citation statements)

References 29 publications

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“…Brand et al (1994) also detected H 2 O masers from this source at similar radial velocity and flux density. Slysh et al (1999) did not find any 6.7 GHz class-II methanol maser emission from this region at a 3σ sensitivity of 3 Jy suggesting that the YSOs here may be very young. Codella & Felli (1995) did not detect any H89α hydrogen recombination line emission from IRAS 07422 suggesting that this source is very young and has not yet formed a diffuse Hii region.…”

Section: Introductionmentioning

confidence: 57%

Multiple outflows from the luminous YSO IRAS 07422-2001

Varricatt

2012

A&A

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The luminous young stellar object (YSO) IRAS 07422-2001 is studied in the infrared (IR). We discover star forming activity in embedded clusters located in a cloud detected at mid-IR wavelengths in emission. Multiple outflows are discovered from these clusters in the H 2 ro-vibrational line at 2.122 μm. We detect at least six outflows from the cluster associated with the IRAS source and another outflow from a source located in a cluster detected ∼2.7 arcmin NE of the IRAS source. Additional star formation is taking place in two other cluster candidates within the cloud. Three of the YSOs in the cluster associated with the IRAS source are detected at 11.2 μm at an angular resolution of ∼0.8 . We have a tentative detection of a circumstellar disk in this cluster, seen as an extinction lane in the J and H-band images. The spectral energy distributions (SEDs) of the dominant YSOs in the cluster associated with the IRAS source and in the NE cluster are studied using radiative transfer models and the properties of the YSOs are estimated. The YSO associated with the IRAS source is probably in a very early Class I stage of formation. The source identified as the dominant YSO in the NE cluster appears to be older than the dominant YSO in the cluster associated with the IRAS source, but its observed flux seems to be contaminated by extra emission, which suggests the presence of a young source contributing to the SED at far-IR wavelengths. The star formation observed in the field of IRAS 07422-2001 supports the idea of hierarchical formation of massive star clusters and the growth of massive young stellar objects near the centres of multiple sub-clusters in a star forming clump through competitive accretion.

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Section: Introductionmentioning

confidence: 57%

Multiple outflows from the luminous YSO IRAS 07422-2001

Varricatt

2012

A&A

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“…Four more masers were observed in the direction of IRAS sources that heve characteristics similsr to UC H ii regions, by Szymczak et al (2000) and Slysh et al (1999). Because of the relatively poor positional accuracy of IRAS, the positions of these masers are rather uncertain.…”

Section: Other Signposts Of Massive-star Formationmentioning

confidence: 99%

A gallery of bubbles

Deharveng

Schüller

Anderson

et al. 2010

A&A

364

584

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Context. This study deals with infrared bubbles, the H ii regions they enclose, and triggered massive-star formation on their borders.Aims. We attempt to determine the nature of the bubbles observed by Spitzer in the Galactic plane, mainly to establish if possible their association with massive stars. We take advantage of the very simple morphology of these objects to search for star formation triggered by H ii regions, and to estimate the importance of this mode of star formation.Methods. We consider a sample of 102 bubbles detected by Spitzer-GLIMPSE, and catalogued by Churchwell et al. (2006; hereafter CH06). We use mid-infrared and radio-continuum public data (respectively the Spitzer-GLIMPSE and -MIPSGAL surveys and the MAGPIS and VGPS surveys) to discuss their nature. We use the ATLASGAL survey at 870 μm to search for dense neutral material collected on their borders. The 870 μm data traces the distribution of cold dust, thus of the dense neutral material where stars may form. Results. We find that 86% of the bubbles contain ionized gas detected by means of its radio-continuum emission at 20-cm. Thus, most of the bubbles observed at 8.0 μm enclose H ii regions ionized by O-B2 stars. This finding differs from the earlier CH06 results (∼25% of the bubbles enclosing H ii regions). Ninety-eight percent of the bubbles exhibit 24 μm emission in their central regions. The ionized regions at the center of the 8.0 μm bubbles seem to be devoid of PAHs but contain hot dust. PAH emission at 8.0 μm is observed in the direction of the photodissociation regions surrounding the ionized gas. Among the 65 regions for which the angular resolution of the observations is high enough to resolve the spatial distribution of cold dust at 870 μm, we find that 40% are surrounded by cold dust, and that another 28% contain interacting condensations. The former are good candidates for the collect and collapse process, as they display an accumulation of dense material at their borders. The latter are good candidates for the compression of pre-existing condensations by the ionized gas. Thirteen bubbles exhibit associated ultracompact H ii regions in the direction of dust condensations adjacent to their ionization fronts. Another five show methanol masers in similar condensations. Conclusions. Our results suggest that more than a quarter of the bubbles may have triggered the formation of massive objects.Therefore, star formation triggered by H ii regions may be an important process, especially for massive-star formation.

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“…Slysh et al (1999) find that in those sources where 6.7 and 44 GHz masers coexist, the ratio of their flux density can be used to discriminate class I from class II masers. On the other hand, no correlation was found when comparing 6.7 with 12.2 GHz counterparts, except for the clear fact that 6.7 GHz masers are always found to be stronger in flux and in brightness temperature when assuming a constant source size (Malyshev & Sobolev 2003).…”

Section: Introductionmentioning

confidence: 95%

“…For instance, Slysh et al (1999) found that methanol masers show a clear velocity difference relative to the velocity of the parent cloud (a comparison made with the velocity of CS). This could suggest an origin for methanol masers in discs seen edge-on.…”

Section: Introductionmentioning

confidence: 99%

A general catalogue of 6.7 GHz methanol masers

Pestalozzi

Chrysostomou

Collett

et al. 2006

A&A

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Context. Methanol masers at 6.7 GHz are recognised markers of high-mass star formation regions. The study of their distribution in the Galaxy gives important insights into the star formation activity of the Milky Way. We present a statistical analysis on the General Catalogue of 6.7 GHz methanol masers in the Galaxy with the aim of extracting global properties of the masers. Aims. We provide constraints on the luminosity function of 6.7 GHz methanol masers and on their total number in the Galaxy. Methods. We model the spatial distribution of the masers in the Milky Way by using their distribution in galactocentric distance which is unambiguous once a rotation curve for the Galaxy is assumed. This is the starting point for determining the luminosity function of the masers.Results. The luminosity function of 6.7 GHz methanol masers is modelled as a power-law with sharp cutoffs and having an index lying between −1.5 and −2. We also predict the number of detections of methanol masers assuming different sensitivity limits in the observations.

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The Medicina survey of methanol masers at 6.7 GHz

Cited by 96 publications

References 29 publications

Multiple outflows from the luminous YSO IRAS 07422-2001

Multiple outflows from the luminous YSO IRAS 07422-2001

A gallery of bubbles

A general catalogue of 6.7 GHz methanol masers

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