Research output per year
Research output per year
Research output: Contribution to journal › Article › peer-review
We have used the Australia Telescope Compact Array (ATCA) to make a sensitive (5σ ≃ 100 mJy) search for maser emission from the 4765-MHz 2Π1/2 F = 1 → 0 transition of OH. 55 star formation regions were searched and maser emission with a peak flux density in excess of 100 mJy was detected toward 14 sites, with 10 of these being new discoveries. In addition we observed the 4750-MHz 2Π1/2 F = 1 → 1 transition towards a sample of star formation regions known to contain 1720-MHz OH masers, detecting marginal maser emission from G348.550-0.979. If confirmed this would be only the second maser discovered from this transition. The occurrence of 4765-MHz OH maser emission accompanying 1720-MHz OH masers in a small number of well-studied star formation regions has led to a general perception in the literature that the two transitions favour similar physical conditions. Our search has found that the presence of the excited-state 6035-MHz OH transition is a much better predictor of 4765-MHz OH maser emission from the same region than 1720-MHz OH maser emission is. Combining our results with those of previous high-resolution observations of other OH transitions we have examined the published theoretical models of OH masers and find that none of them predicts any conditions in which the 1665-, 6035- and 4765-MHz transitions are inverted simultaneously.
Original language | English |
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Pages (from-to) | 307-317 |
Number of pages | 11 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 333 |
Issue number | 2 |
DOIs | |
Publication status | Published - 21 Jun 2002 |
Research output: Contribution to journal › Comment/debate › peer-review