English

Vibrationally Excited Molecular Hydrogen Near Herschel 36

Astrophysics of Galaxies 2015-06-19 v1

Abstract

We present the first high resolution UV spectra toward Herschel 36, a Trapezium-like system of high-mass stars contained within the Lagoon Nebula (M8, NGC 6523). The spectra reveal extreme ro-vibrational excitation of molecular hydrogen in material at a single velocity or very small range of velocities, with this component presumably lying near the star system and undergoing fluorescent excitation. The overall H2_2 excitation is similar to, but apparently larger than, that seen towards HD 37903 which previously showed the largest vibrationally excited H2_2 column densities seen in UV absorption spectra. While the velocities of the highly excited H2_2 lines are consistent within each observation, it appears that they underwent a \sim60 km s1^{-1} redshift during the 3.6 years between observations. In neither case does the velocity of the highly excited material match the velocity of the bulk of the line-of-sight material which appears to mostly be in the foreground of M8. Recent work shows unusually excited CH and CH+^{+} lines and several unusually broad Diffuse Interstellar Bands towards Herschel 36. Along with the H2_2 excitation, all of these findings appear to be related to the extreme environment within \sim0.1 pc of the massive young stellar system.

Keywords

Cite

@article{arxiv.1404.1648,
  title  = {Vibrationally Excited Molecular Hydrogen Near Herschel 36},
  author = {Brian L. Rachford and Theodore P. Snow and Teresa L. Ross},
  journal= {arXiv preprint arXiv:1404.1648},
  year   = {2015}
}

Comments

11 pages, 11 figures, accepted for publication in ApJ