OH masers trace diverse physical processes, from the expanding envelopes around evolved stars to star-forming regions or supernovae remnants. Providing a survey of the ground-state OH maser transitions in the northern hemisphere inner Milky Way facilitates the study of a broad range of scientific topics. We want to identify the ground-state OH masers at 18 cm wavelength in the area covered by "The HI/OH/Recombination line survey of the Milky Way (THOR)". We will present a catalogue of all OH maser features and their possible associated environments. The THOR survey covers longitude and latitude ranges of 14.3{deg}<l<66.8{deg} and b<+/-1.25{deg}. All OH ground state lines ^2^{PI}_3/2_(J=3/2) at 1612 (F=1-2), 1665 (F=1-1), 1667 (F=2-2) and 1720MHz (F=2-1) have been observed, employing the Very Large Array (VLA) in its C configuration. The spatial resolution of the data varies between 12.5" and 19", the spectral resolution is 1.5km/s, and the rms sensitivity of the data is 10mJy/beam per channel. We identify 1585 individual maser spots (corresponding to single spectral features) distributed over 807 maser sites (regions of size ~10^3^-10^4^AU). Based on different criteria from spectral profiles to literature comparison, we try to associate the maser sites with astrophysical source types. Approximately 51% of the sites exhibit the double-horned 1612MHz spectra typically emitted from the expanding shells of evolved stars. The separations of the two main velocity features of the expanding shells typically vary between 22 and 38km/s. In addition to this, at least 20% of the maser sites are associated with star-forming regions. While the largest fraction of 1720MHz maser spots (21 out of 53) is associated with supernova remnants, a significant fraction of the 1720MHz maser spots (17) are also associated with star-forming regions. We present comparisons to the thermal ^13^CO(1-0) emission as well as to other surveys of class II CH_3_OH and H_2_O maser emission. The catalogue attempts to present associations to astrophysical sources where available, and the full catalogue is available in electronic form. This OH maser catalogue presents a unique resource of stellar and interstellar masers in the northern hemisphere. It provides the basis for a diverse range of follow-up studies from envelopes around evolved stars to star-forming regions and Supernova remnants.
We present OH maser observations at 1612, 1665, 1667, and 1720MHz for 86 likely post-asymptotic giant branch (post-AGB) stars selected from a survey of 1612MHz maser sources in the Galactic plane. The observations were taken with the Parkes Telescope and the Australia Telescope Compact Array between 2002 September and 2003 August. We redetected all 86 sources at 1612MHz, while 27 sources were detected at 1665MHz and 45 at 1667MHz. One source was redetected at 1720MHz. We present a classification scheme for the maser profiles and show that 25% of sources in our sample are likely to have asymmetric or bipolar outflows.
Recent studies of methanol and ground-state OH masers at very high spectral resolution have shed new light on small-scale maser processes. The nearby source W3(OH), which contains numerous bright masers in several different transitions, provides an excellent laboratory for high spectral resolution techniques. We present a model of W3(OH) based on European VLBI Network (EVN) observations of the rotationally excited 6030 and 6035MHz OH masers taken at 0.024km/s spectral resolution.
Masers are important tracers of the early evolution of young high mass stars, but the relationship between different types of maser and the evolutionary state of the exciting source remains unclear. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************
The data are the results of a search for 1612MHz OH circumstellar masers in a colour limited sample of cool ORAS sources. Most of the observations were made at the Nancay radio telescope between January 1986 and February 1988; some were observed or reobserved later, between 1990 and 1992.
We present the final results from the Arecibo Observatory OH megamaser survey. We discuss in detail the properties of the remaining 18 OH megamasers detected in the survey, including three redetections. We place upper limits on the OH emission from 85 nondetections and examine the properties of 25 ambiguous cases for which the presence or absence of OH emission could not be determined. The complete survey has discovered 50 new OH megamasers (OHMs) in (ultra)luminous infrared galaxies ([U]LIRGs), which doubles the sample of known OHMs and increases the sample at z>0.1 sevenfold.
OH megamasers are the most luminous masers in the universe. The total of 109 OH megamaser (OHM) galaxies known so far have been collected, and cross-identifications of those OHM galaxies with Two Micron All Sky Survey (2MASS) sources are made in this paper. Using 2MASS (Cat. II/246) and IRAS (Cat. II/125, II/156) data, the infrared properties of OHM-detected and non-detected sources are compared.
The excited states of OH masers detected in the environment of high-mass young stellar objects (HMYSOs) are important for improving our understanding of the physical conditions of these objects and also provide information about their magnetic fields. We aim to search for excited-state OH 6035MHz maser emission in HMYSOs which might have escaped detection in previous surveys or were never searched for. Methods. A sample of HMYSOs derived from untargeted surveys of the 6668MHz methanol maser line was observed at 6035MHz OH transition with the Torun 32m radio telescope. The 6035MHz detections were observed in the OH 6031MHz line. Two-thirds of the detections were observed at least three times over a two-year period. Out of 445 targets, 37 were detected at 6035MHz, including seven new discoveries. The 6031MHz line was detected towards ten 6035MHz sources, one of which was not previously reported. All the newly detected sources are faint with the peak flux density lower than 4Jy and show significant or high variability on timescales of 4 to 20 months. Zeeman pair candidates identified in three new sources imply a magnetic field intensity of 2-11mG. Comparison of our spectra with those obtained ~10yr ago indicates different degrees of variability but there is a general increase in the variability index on an ~25yr timescale, usually accompanied by significant changes in the profile shape.
The Arecibo 1612MHz survey of a complete sample of color-selected IRAS sources with 25{mu}m fluxes S(25)>2 Jy detected 393 OH/IR stars. A complementary 1667 and 1665MHz OH survey of these objects is presented here. Main-line masers have been detected in 238 surveyed objects: 18 exhibit only 1665MHz emission, 220 exhibit 1667MHz masers, and 119 exhibit both. The main lines were not detected in 159 objects.
