56 research outputs found
The Source of Maser Emission W33C (G12.8-0.2)
Results of observations of the maser sources toward the W33C region
(G12.8-0.2) carried out on the 22-m radio telescope of the Pushchino Radio
Astronomy Observatory in the 1.35-cm H2O line and on the Large radio telescope
in Nancay (France) in the main (1665 and 1667 MHz) and satellite (1612 and 1720
MHz) OH lines are reported. Multiple, strongly variable short-lived H2O
emission features were detected in a broad interval of radial velocities, from
-7 to 55 km/s. OH maser emission in the 1667-MHz line was discovered in a
velocity range of 35-41 km/s. Stokes parameters of maser emission in the main
OH lines 1665 and 1667 MHz were measured. Zeeman splitting was detected in the
1665-MHz line at 33.4 and 39.4 km/s and in the 1667 MHz line only at 39.4 km/s.
The magnetic field intensity was estimated. A appreciable variability of Zeeman
splitting components was observed at 39 and 39.8 km/s in both main lines. The
extended spectrum and fast variability of the H2O maser emission together with
the variability of the Zeeman splitting components in the main OH lines can be
due to the composite clumpy structure of the molecular cloud and to the
presence in it of large-scale rotation and bipolar outflow as well as of
turbulent motions of material.Comment: 7 pages, 2 tables, 8 figures, accepted by Astronomicheskii Zhurnal
(Astronomy Reports
The brightest OH maser in the sky: a flare of emission in W75 N
A flare of maser radio emission in the OH-line 1665 MHz has been discovered
in the star forming region W75 N in 2003, with the flux density of about 1000
Jy. At the time it was the strongest OH maser detected during the whole history
of observations since the discovery of cosmic masers in 1965. The flare
emission is linearly polarized with a degree of polarization near 100%. A
weaker flare with a flux of 145 Jy was observed in this source in 2000 - 2001,
which was probably a precursor of the powerful flare. Intensity of two other
spectral features has decreased after beginning of the flare. Such variation of
the intensity of maser condensation emission (increasing of one and decreasing
of the other) can be explained by passing of the magneto hydrodynamic shock
across regions of enhanced gas concentration.Comment: 9 pages with 2 figures, accepted for publication in Astronomy Letter
Observations of Massive Star Forming Regions with Water Masers: Mid-Infrared Imaging
We present here a mid-infrared imaging survey of 26 sites of water maser
emission. Observations were obtained at the InfraRed Telescope Facility 3-m
telescope with the University of Florida mid-infrared imager/spectrometer
OSCIR, and the JPL mid-infrared camera MIRLIN. The main purpose of the survey
was to explore the relationship between water masers and the massive star
formation process. It is generally believed that water masers predominantly
trace outflows and embedded massive stellar objects, but may also exist in
circumstellar disks around young stars. We investigate each of these
possibilities in light of our mid-infrared imaging. We find that mid-infrared
emission seems to be more closely associated with water and OH maser emission
than cm radio continuum emission from UC HII regions. We also find from the
sample of sources in our survey that, like groups of methanol masers, both
water and OH masers have a proclivity for grouping into linear or elongated
distributions. We conclude that the vast majority of linearly distributed
masers are not tracing circumstellar disks, but outflows and shocks instead.Comment: 49 pages; 23 figures; To appear in February 2005 ApJS; To download a
version with better quality figures, go to
http://www.ctio.noao.edu/~debuizer
- …