Velocities and rotational excitation of interstellar H2 toward Pi Scorpii
| Autor: | E. F. van Dishoeck, J.F. Lees, E.M. Wilcots, E.B. Jenkins |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 1989 |
| Předmět: |
Physics
Absorption spectroscopy absorption spectra rotational spectra interstellar gas Rotational transition Flux Velocity dispersion Astronomy and Astrophysics Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics line spectra ultraviolet spectra Astronomical spectroscopy Spectral line molecular excitation stellar spectra Optical pumping Stars Space and Planetary Science hydrogen Atomic physics Astrophysics::Galaxy Astrophysics |
| Zdroj: | None |
| Popis: | A spectrum of Pi Sco showing numerous atomic lines and 70 absorption features from the Lyman and Werner transitions of interstellar H2 in rotational level J from zero to five is presented. Their shapes of the composite column density profiles are very nearly Gaussian with a one-dimensional rms velocity dispersion of 3 km/s. The behavior of shifts in the inferred N(H2) as a function of velocity are consistent with the overall profiles being composed of nearly symmetrical, tightly paced assemblies of about seven unresolved components. The relative overall column densities in the higher J levels of H2 are consistent with a model where these states are populated by optical pumping through the Lyman and Werner transitions, powered by UV radiation from nearby stars. The slight narrowing of the high-J profiles may be due to small clumps of H2 at radial velocities some 5-8 km/s from the core of the profile are exposed to a pumping flux about 10 times lower than that for the material near the profile's center. |
| Databáze: | OpenAIRE |
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