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| Paper: |
Absorption Lines from Neutral Envelopes of Planetary Nebulae |
| Volume: |
199, Asymmetrical Planetary Nebulae II: From Origins to Microstructures |
| Page: |
325 |
| Authors: |
Sirbaugh French, Rica; Dinerstein, Harriet L.; Sneden, Christopher |
| Abstract: |
We have obtained new, high-spectral resolution (~5 km/s) observations of 44 planetary nebulae in the region of the Na I lines at 5889.95, 5895.92 ÅÅ. These lines have been shown by Dinerstein & Sneden (1988) and Dinerstein, Sneden, & Uglum (1995) to trace the presence of neutral envelopes in planetary nebulae. Our new observations, obtained with the McDonald Observatory 2.7m telescope, have resulted in new detections of neutral material, as well as better definition of the circumstellar absorption line profiles. In some cases, we also observe re-emission from the resonantly scattered Na I photons. The radial velocities of the observed features provide information on the kinematics of the neutral layers. The spectra cover the range 3600 - 10,500 Å and can be used to search for other, generally weaker absorption features from the neutral and molecular layers, such as Ca II, Ca I, K I, and some molecules. |
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