Abstract. Two independent, largely overlapping 1612 MHz data sets were searched for OH/IR stars in the Galactic center. One set, taken with the Very Large Array in the period 1988 to 1991, consists of 17 epochs monitoring data of Van Langevelde et al. (1993). The other set was observed in 1994, using the Australia Telescope Compact Array. This article describes the data reduction procedures as well as a different way of searching image cubes for narrow line sources, and lists 1 a total of 155 double peak OH maser detections within 18 or 40 projected parsecs of Sagittarius A*, the compact radio continuum source in the Galactic nucleus. Presented are 65 formerly unseen double peaked 1612 MHz emitters, of which 52 are OH/IR stars. Also given are 3 single peak sources, which we believe to be masers of OH/IR stars. Apart from being less bright in their 1612 MHz OH maser line, the previously unknown OH/IR stars do not seem to be different from the previously known population of OH/IR stars in the Galactic center. We find that the OH/IR star OH maser luminosity distribution peaks at L OH ≈ 10 43.4 photons per second. Further physical and kinematical analysis of the new sample will be presented in additional papers.
Context. Molecular oxygen, O 2 , has been expected historically to be an abundant component of the chemical species in molecular clouds and, as such, an important coolant of the dense interstellar medium. However, a number of attempts from both ground and from space have failed to detect O 2 emission. Aims. The work described here uses heterodyne spectroscopy from space to search for molecular oxygen in the interstellar medium. Methods. The Odin satellite carries a 1.1 m sub-millimeter dish and a dedicated 119 GHz receiver for the ground state line of O 2 . Starting in 2002, the star forming molecular cloud core ρ Oph A was observed with Odin for 34 days during several observing runs. Results. We detect a spectral line at v LSR = +3.5 km s −1 with ∆v FWHM = 1.5 km s −1 , parameters which are also common to other species associated with ρ Oph A. This feature is identified as the O 2 (N J = 1 1 −1 0 ) transition at 118 750.343 MHz. Conclusions. The abundance of molecular oxygen, relative to H 2 , is 5 × 10 −8 averaged over the Odin beam. This abundance is consistently lower than previously reported upper limits.
Abstract. The Odin satellite, which can observe the 1 10 -1 01 rotational line at 557 GHz of ortho water with a high spectral resolution (80 m s −1 ) and a spatial resolution of 2
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