Enhanced density and magnetic fields in interstellar OH masers

¹ Jansky Fellow, National Radio Astronomy Observatory, PO Box O, 1003 Lopezville Road, Socorro, NM 87801, USA e-mail: vfish@nrao.edu
² Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
³ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, Bonn 53121, Germany

Received: 6 April 2006
Accepted: 26 July 2006

Abstract

Aims.We have observed the 6030 and 6035 MHz transitions of OH in high-mass star-forming regions to obtain magnetic field estimates in both maser emission and absorption.

Methods.Observations were taken with the Effelsberg 100 m telescope.

Results.Our observations are consistent with previous results, although we do detect a new 6030 MHz maser feature near -70 km s^-1 in the vicinity of W3(OH). In absorption we obtain a possible estimate of  mG for the average line-of-sight component of the magnetic field in the absorbing OH gas in K3-50 and submilligauss upper limits for the line-of-sight field strength in DR 21 and W3.

Conclusions.These results indicate that the magnetic field strength in the vicinity of OH masers is higher than that of the surrounding, non-masing material, which in turn suggests that the density of masing OH regions is higher than that of their surroundings.