Issue |
A&A
Volume 392, Number 1, September II 2002
|
|
---|---|---|
Page(s) | 277 - 286 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20020907 | |
Published online | 22 August 2002 |
6.7 GHz methanol masers at sites of star formation
A blind survey of the Galactic plane between
20°
40° and
0
52
Toruń Centre for Astronomy, Nicolaus Copernicus University, Gagarina 11, 87-100 Toruń, Poland
Corresponding author: M. Szymczak, msz@astro.uni.torun.pl
Received:
30
April
2002
Accepted:
6
June
2002
We report the results of an unbiased survey for 6.7 GHz methanol
maser emission of a ~21 deg2 strip of the Galactic plane carried
out with the 32 m Toruń radio telescope.
An area at 20° 40°,
0
52 was surveyed in an equilateral triangular grid with
a sensitivity limit of about 1.6 Jy. We detected a total of 100 sources,
26 of which are new detections. All the new sources are of moderate intensity
and their peak flux densities have median value of 6.5 Jy, i.e. about
half that of previously known sources in the sample.
About 80% of maser sources have IR counterpart candidates within a
radius but not all the IRAS counterparts of methanol masers have colours typical
of ultracompact HII regions. An excess of masers unassociated with IR sources
occurs at
because of incompleteness of IR catalogues
due to strong confusion near the tangential region of the spiral arm.
Our unbiased survey doubled the number of detections as compared to IRAS-based
observations. Within the positional uncertainty of
about one third
of the methanol sources have radio continuum counterparts at 5 GHz of a flux
density greater than 2.5–10 mJy. The distribution of methanol sources
appears to be consistent with a clustered mode of formation of massive stars.
Key words: masers / surveys / stars: formation / ISM: molecules / radio lines: ISM / HII regions
© ESO, 2002
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