A study of the diffuse interstellar gas near the Pleiades

Abstract

view Abstract Citations (24) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A study of the diffuse interstellar gas near the Pleiades Federman, S. R. Abstract Interstellar gas toward the Pleiades was studied by observing lines of CH, CH+, and K I along three lines of sight, taking the equivalent width, velocity at line center in the local standard of rest, and the Doppler parameter. Evidence for a shock of 10-15 km/s could be seen in the 3-4 km/s blueshift of the CH line relative to the CH+ line toward 20 Tau, the largest shock yet observed in a survey of CH and CH+ in diffuse interstellar clouds. Toward nu Tau, the narrow K I feature indicated a weak shock. Using the ratio r of atomic species with low ionization potentials to molecular hydrogen, the distance of the gas to the stars is found to be about 0.3 pc. This distance is inconsistent with the observed distribution of molecular hydrogen among its rotational levels, but the discrepancy is eliminated by considering collisions of atomic hydrogen with molecular hydrogen to be responsible for the distribution. Publication: The Astrophysical Journal Pub Date: February 1982 DOI: 10.1086/159662 Bibcode: 1982ApJ...253..601F Keywords: Astronomical Spectroscopy; Gaseous Diffusion; Interstellar Gas; Line Spectra; Molecular Ions; Pleiades Cluster; Star Clusters; Astronomical Models; Gas Density; Interstellar Extinction; Molecular Rotation; Molecular Spectra; Monatomic Gases; Potassium; Radicals; Stellar Evolution; Astrophysics full text sources ADS |