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A cloud collision model for water maser excitation
1Astronomy Department, University of California at Berkeley, USA.
The Astrophysical Journal
|June 1, 1986
Summary
High-velocity collisions can power water (H2O) maser emission in space. This model explains transient maser "bullets" by a hot-dust, cold-gas mechanism, though not long-lived masers.
Area of Science:
- Astrophysics
- Astrochemistry
- Maser Physics
Background:
- Water (H2O) masers are observed in various astrophysical environments.
- Understanding the excitation mechanisms for maser emission is crucial for interpreting observations.
Purpose of the Study:
- To investigate the role of high-velocity collisions in exciting H2O maser emission.
- To explain the observed properties of transient, high-velocity maser features.
Main Methods:
- Modeling collisional shock fronts in dense interstellar clouds.
- Applying the Goldreich and Kwan "hot-dust cold-gas" maser pumping scheme.
- Analyzing radiative precursor diffusion and its effect on gas and dust temperatures.
Main Results:
- High-velocity collisions provide the energy for H2O maser emission.
- A radiative precursor heats dust while keeping gas cool, enabling transient maser action.
- The model successfully explains rapid variations, narrow line widths, and short lifetimes of maser features.
Conclusions:
- Collisional shock models offer a viable explanation for transient H2O maser emission.
- This mechanism accounts for observed properties of high-velocity maser "bullets" in sources like Orion.
- The model highlights the importance of dust-gas interactions in maser excitation.