| About 40 per cent of colour-selected IRAS sources are without 161 2-MHz masers, despite IR colours that are indicative of thick circumstellar shells, and often despite spectral classifications showing that they are O-rich. We report here on a search for water and mainline OH masers from the 26 OH/IR star colour mimics identified by Lewis with a 2n-3n LRS type. We find water masers in six, and mainline masers in a further five. These 11 sources are indubitably O-rich, and many have a velocity range characteristic of, and appropriate to, masers associated with circumstellar shells. However, 17 per cent of 2n-3n sources appear to have no circumstellar masers we estimate that 11 per cent may never exhibit a maser. |
Target sources:
IRAS
Comments:
Spectral type was set to:
""S"", where only one peak was found.
""D"", where two peaks were found.
The columns for the blue- and red-shifted velocities were filled with the two highest peaks listed. The leftmost and the rightmost peaks were used to calculate the radial velocity vrad and the expansion velocity vexp of the shell.
Velocity resolution: 0.44 km/s
Upper limit for non-detections: 0.030 Jy (3σ)
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