The Search for H- in Astrophysical Environments
Abstract
The negative ion H- is widely understood to be important in many astrophysical environments, including the atmospheres of late-type stars like the Sun. However, the ion has never been detected spectroscopically outside the laboratory. A search for the far-ultraviolet autodetaching transitions of H- in interstellar and circumstellar matter seems to be the best hope for directly detecting this ion. We undertook a highly sensitive search using data from the FUSE instrument. We concentrated on two types of sight lines: planetary nebulae, where model calculations suggest a sufficient abundance of H- to be determined, and translucent clouds, where H- might form on dust grains as an intermediate step in molecular hydrogen formation. Upper limits on H- abundances were set.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2008
- DOI:
- 10.1086/590242
- Bibcode:
- 2008ApJ...684..358R
- Keywords:
-
- ISM: abundances;
- ISM: atoms;
- ISM: lines and bands;
- planetary nebulae: general