Observation of fine structure in the cold phase of the local interstellar medium using K I absorption

Trapero, Joaquin; Beckman, John E.; Genova, Ricardo; McKeith, Conal D.
Bibliographical reference

Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 394, no. 2, Aug. 1, 1992, p. 552-564.

Advertised on:
8
1992
Number of authors
4
IAC number of authors
3
Citations
17
Refereed citations
15
Description
The K I 7699-A resonance absorption line was used to observe a group of 18 early-type stars within a 200-pc radius of the sun with a signal-to-noise ratio of 50-250. The interstellar absorptions provide a way to 'tag' a cloud via its radial velocity to within +/-1.5 km/s. Based on the hypothesis of pressure confinement, the temperatures of the clouds are estimated at 100 K or less. The mass fraction of the local interstellar medium (LISM) is found to be high in these clouds, at least 80 percent of the total, whereas the filling factor is low, well below 10 percent of the total LISM volume. One cloud with high densities and lower temperatures was detected which is thought to be on the edge of atomic-molecular equilibrium.