Detection of 35 new 51-60 A+ -methanol masers towards IRAS sources

Aims. We report the discovery of periodic flares of 6.7 GHz methanol maser in the young massive stellar object G22.357+0.066. Methods. The target was monitored in the methanol maser line over 20 months with the Torun 32 m telescope. The emission was also mapped at two epochs using the EVN. Results. The 6.7 GHz methanol maser shows periodic variations with a period of 179 days. The periodic behavior is stable for the last three densely sampled cycles and has even been stable over ∼12 years, as the archival data suggest. The maser structure mapped with the EVN remains unchanged at two epochs just at the putative flare maxima separated by two years. The time delays of up to ∼16 days seen between maser features are combined with the map of spots to construct the 3-dimensional structure of the maser region. The emission originating in a single ∼100 AU layer can be modulated by periodic changes in the infrared pumping radiation or in the free-free background emission from an HII region.

show abstract

“…The position of 6.7 GHz maser (Schutte et al 1993) measured with VLBI (Bartkiewicz et al 2009) coincides within 0. 05 with the water maser ).…”

Section: Introductionsupporting

confidence: 58%

Periodic variability of 6.7 GHz methanol masers in G22.357 + 0.066

Szymczak

Wolak

Bartkiewicz

et al. 2011

A&A

View full text Add to dashboard Cite

show abstract

“…For more than a decade now, searches for new methanol maser sources have been undertaken by a number of authors, e.g. MacLeod et al (1992); Schutte et al (1993); Caswell et al (1995); Ellingsen (1996); Szymczak et al ( , 2002; Pestalozzi et al (2002b). All together, this brought the number of known methanol masers to 519 (Pestalozzi et al 2005).…”

Section: Introductionmentioning

confidence: 99%

A general catalogue of 6.7 GHz methanol masers

Pestalozzi

Chrysostomou

Collett

et al. 2006

A&A

View full text Add to dashboard Cite

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.

show abstract

“…By modeling HCO + , H 13 CO + , CS, and C 34 S spectra obtained at an angular resolution of $16 00 , Ramesh, Bronfman, & Deguchi (1997) demonstrate that the observed line profiles can be explained by a collapsing hot core of about 800 M , which is hidden behind a cold ($4 K) and dense (3 Â 10 4 cm À3 ) envelope of about 200 M . The IRAS 18507 region is also associated with variable H 2 O maser (Scalise, Rodríguez, & Mendoza-Torres 1989;Palla et al 1991;Miralles et al 1994) and CH 3 OH maser emission (Schutte et al 1993;Szymczak, Hrynek, & Kus 2000). Molinari et al (1996Molinari et al ( , 1998 observed IRAS 18507 (labeled ''Mol 74'' in their papers) and estimated a deconvolved size of the UC H ii region of 0B7 (0.013 pc at D ¼ 3:9 kpc).…”

Section: Introductionmentioning

confidence: 99%

Discovery of a Massive Protostar near IRAS 18507+0121

Shepherd¹,

Nürnberger²,

Bronfman³

2004

ApJ

View full text Add to dashboard Cite

We have observed the massive star-forming region IRAS 18507+0121 at millimeter wavelengths in 3 mm continuum emission, H 13 CO + ( J ¼ 1 0) and SiO (v ¼ 0, J ¼ 2 1) line emission, and at near-infrared (NIR) wavelengths between 1.2 and 2.1 m. Two compact molecular cores are detected: one north and one south, separated by $40 00 . The northern molecular core contains a newly discovered, deeply embedded, B2 protostar surrounded by several hundred solar masses of warm gas and dust, G34.4+0.23 MM. Based on the presence of warm dust emission and the lack of detection at NIR wavelengths, we suggest that G34.4+0.23 MM may represent the relatively rare discovery of a massive protostar (e.g., analogous to a low-mass ''Class 0'' protostar). The southern molecular core is associated with an NIR cluster of young stars and an ultracompact H ii region, G34.4+0.23, with a central B0.5 star. The fraction of NIR stars with excess infrared emission indicative of circumstellar material is greater than 50%, which suggests an upper limit on the age of the IRAS 18507+0121 starforming region of 3 Myr.

show abstract

Detection of 35 new 51-60 A+ -methanol masers towards IRAS sources

Cited by 76 publications

References 0 publications

Periodic variability of 6.7 GHz methanol masers in G22.357 + 0.066

Periodic variability of 6.7 GHz methanol masers in G22.357 + 0.066

A general catalogue of 6.7 GHz methanol masers

Discovery of a Massive Protostar near IRAS 18507+0121

Contact Info

Product

Resources

About