Interstellar H2 toward HD 37903

Abstract

We present an analysis of interstellar H2 toward HD 37903, which is a hot, B 1.5 V star located in the NGC 2023 reflection nebula. Meyer et al. (2001) have used a rich spectrum of vibrationally excited H2 observed by the HST to calculate a model of the interstellar cloud toward HD 37903. We extend Mayer's analysis by including the v"=0 vibrational level observed by the FUSE satellite. The T01 temperature should not be interpreted as a rotational temperature, but rather as a temperature of thermal equilibrium between the ortho and para H2. The ortho to para H2 ratio is lower for collisionally populated levels than for the levels populated by fluorescence. The PDR model of the cloud located in front of HD 37903 points to a gas temperature Tkin=110-377 K, hydrogen density nH=1874-544 cm^-3 and the star-cloud distance of 0.45 pc.

References in corpus (1)

• Observational Properties of Rotationally Excited Molecular Hydrogen In Translucent Lines of Sight

Cited by in corpus (9)

• Molecular excitation in the Interstellar Medium: recent advances in collisional, radiative and chemical processes
• Anomalous Diffuse Interstellar Bands in the Spectrum of Herschel 36. I. Observations of Rotationally Excited CH and CH+ Absorption and Strong, Extended Redward Wings on Several DIBs
• The Behavior of Selected Diffuse Interstellar Bands with Molecular Fraction in Diffuse Atomic and Molecular Clouds
• HD 62542: Probing the Bare, Dense Core of a Translucent Interstellar Cloud
• Dark Dust and single-cloud sightlines in the ISM
• Interstellar H2 toward HD 147888
• Broadened profiles of Diffuse Interstellar Bands
• Thermal Pressure in Diffuse H2 Gas Measured by Herschel [C II] Emission and FUSE UV H2 Absorption
• Vibrationally Excited Molecular Hydrogen Near Herschel 36