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New interstellar masers in nonmetastable ammonia
S C Madden1, W M Irvine, H E Matthews
1Department of Physics and Astronomy, University of Massachusetts, USA.
The Astrophysical Journal
|January 15, 1986
Summary
Astronomers detected ammonia masers in space for the first time, observing emission from highly excited nonmetastable levels. These findings in active star formation regions offer new insights into astrochemistry.
Area of Science:
- Astronomy
- Astrophysics
- Astrochemistry
Background:
- Nonmetastable ammonia (NH3) inversion transitions involve highly excited states.
- Previous detections of these lines were weak and attributed to thermal emission.
Purpose of the Study:
- To report the first definitive astronomical detections of ammonia masers.
- To characterize the emission properties of nonmetastable ammonia inversion transitions.
Main Methods:
- Observational astronomy using radio telescopes.
- Analysis of ammonia inversion transition spectral lines.
Main Results:
- Detected maser-like emission from NH3 (J, K) = (9, 6) transitions towards W51, NGC 7538, W49, and DR 21(OH).
- Observed NH3 (6, 3) line in emission (W51) and absorption (NGC 7538).
- Emission features showed high intensity and narrow line widths (0.5-1.5 km s-1), distinct from thermal emission.
Conclusions:
- These are the first confirmed detections of ammonia masers in space.
- The (9, 6) emission in W49 exhibited temporal variability over 4 months.
- Highly excited ammonia lines are associated with active star formation regions containing compact H II regions and other masers.