SIMBAD references

2008MNRAS.390...49M - Mon. Not. R. Astron. Soc., 390, 49-58 (2008/October-2)

A search for OH 6 GHz maser emission towards supernova remnants.


Abstract (from CDS):

OH masers at 1720 MHz have proven to be excellent indicators of interactions between supernova remnants and molecular clouds. OH-excitation calculations suggest that the 6049-MHz OH-maser line is excited for higher column densities than for the 1720-MHz line. Previous observations and modelling of 1612-, 1665- and 1667-MHz OH absorption and 1720-MHz OH masers indicated that the column densities in some supernova remnants, ∼1017/cm2, may be high enough for 6049-MHz OH masers to exist. It is therefore a potentially valuable indicator of remnant-cloud interaction.

We present excitation calculations predicting the formation of 6049-MHz OH masers and results of a survey, using the Parkes Methanol Multibeam receiver for 6049-, 6035- and 6030-MHz OH masers toward 35 supernova remnants, a star-forming region and four fields in the Large and Small Magellanic Clouds.

Two new sites of 6035- and 6030-MHz OH-maser emission associated with star-forming regions have been discovered, but no 6049-MHz masers were detected to a brightness temperature limit of ∼0.3-0.6 K, even though modelling of the OH excitation suggests that maser emission should have been detected. Our upper limits indicate the OH column density for a typical remnant ≲1016.4/cm2, which conflicts with observed and modelled column densities. One possible explanation is that 6049-MHz OH masers may be more sensitive to velocity coherence than 1720-MHz OH masers under some conditions.

Abstract Copyright: © 2008 The Authors. Journal compilation © 2008 RAS

Journal keyword(s): masers - stars: formation - supernova remnants - radio lines: ISM

Simbad objects: 45

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