The Arecibo Methanol Maser Galactic Plane Survey. I. Data

Pandian, J. D.; Goldsmith, Paul F.; Deshpande, A. A.

doi:10.1086/510512

Cited by 94 publications

(112 citation statements)

References 24 publications

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“…9 (Kurtz et al 2005). The OH, H 2 O, and 6.7 GHz methanol maser emission are oberved in a nearby direction (respectively, Argon et al 2000;Kurtz & Hofner 2005;Pandian et al 2007; see also Sect. 6.6).…”

Section: N65mentioning

confidence: 85%

A gallery of bubbles

Deharveng

Schüller

Anderson

et al. 2010

A&A

359

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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Section: N65mentioning

confidence: 85%

A gallery of bubbles

Deharveng

Schüller

Anderson

et al. 2010

A&A

359

584

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“…They are relatively common and strong, with more than 1000 sources now known across the Galactic plane (e.g. Pandian et al 2007;Caswell et al 2010; Green et al 2010; arXiv:1711.07589v1 [astro-ph.GA] 21 Nov 2017 Caswell et al 2011;Green et al 2012;Breen et al 2015). The next strongest and common class II methanol maser line is at 12.2-GHz (e.g.…”

Section: Introductionmentioning

confidence: 99%

The 6-GHz Multibeam Maser Survey – III. Comparison between the MMB and HOPS

Breen

Contreras

Ellingsen

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We have compared the occurrence of 6.7-GHz and 12.2-GHz methanol masers with 22-GHz water masers and 6035-MHz excited-state OH masers in the 100 square degree region of the southern Galactic plane common to the Methanol Multibeam (MMB) and H 2 O southern Galactic Plane surveys (HOPS). We find the most populous star formation species to be 6.7-GHz methanol, followed by water, then 12.2-GHz and, finally, excited-state OH masers. We present association statistics, flux density (and luminosity where appropriate) and velocity range distributions across the largest, fully surveyed portion of the Galactic plane for four of the most common types of masers found in the vicinity of star formation regions.Comparison of the occurrence of the four maser types with far-infrared dust temperatures shows that sources exhibiting excited-state OH maser emission are warmer than sources showing any of the other three maser types. We further find that sources exhibiting both 6.7-GHz and 12.2-GHz methanol masers are warmer than sources exhibiting just 6.7-GHz methanol maser emission. These findings are consistent with previously made suggestions that both OH and 12.2-GHz methanol masers generally trace a later stage of star formation compared to other common maser types.

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“…The 6.7 GHz methanol maser transition has been detected from very many massive star-forming regions (Pandian et al 2007;Caswell et al 2010Caswell et al , 2011Green et al 2010Green et al , 2012Szymczak et al 2012). Since the early report of Caswell et al (1995), the temporal properties of methanol masers have been intensively studied.…”

Section: Introductionmentioning

confidence: 99%

Discovery of four periodic methanol masers and updated light curve for a further one

Szymczak

Wolak

Bartkiewicz

2015

Monthly Notices of the Royal Astronomical Society

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We report the discovery of 6.7 GHz methanol maser periodic flares in four massive star forming regions and the updated light curve for the known periodic source G22.357+0.066. The observations were carried out with the Torun 32 m radio telescope between June 2009 and April 2014. Flux density variations with period of 120 to 245 d were detected for some or all spectral features. A variability pattern with a fast rise and relatively slow fall on time-scale of 30−60 d dominated. A reverse pattern was observed for some features of G22.357+0.066, while sinusoidal-like variations were detected in G25.411+0.105. A weak burst lasting ∼520 d with the velocity drift of 0.24 km s −1 yr −1 occurred in G22.357+0.066. For three sources for which high resolution maps are available, we found that the features with periodic behaviour are separated by more than 500 au from those without any periodicity. This suggests that the maser flares are not triggered by large-scale homogeneous variations in either the background seed photon flux or the luminosity of the exciting source and a mechanism which is able to produce local changes in the pumping conditions is required.

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The Arecibo Methanol Maser Galactic Plane Survey. I. Data

Cited by 94 publications

References 24 publications

A gallery of bubbles

A gallery of bubbles

The 6-GHz Multibeam Maser Survey – III. Comparison between the MMB and HOPS

Discovery of four periodic methanol masers and updated light curve for a further one

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