Molecular hydrogen in the vicinity of NGC 7538 IRS 1 and IRS 2 - Temperature and ortho-to-para ratio

Journal Article · Fri Mar 01 04:00:00 UTC 1991 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/169808· OSTI ID:5866940

Hoban, S; Reuter, D C; Mumma, M J; Storrs, A D ^[1]

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1. NASA, Goddard Space Flight Center, Greenbelt, MD (USA)

Near-infrared spectroscopic observations of the active star-forming region near NGC 7538 IRS 1 and IRS 2 were made. The relative intensities of the v = 1-0 Q(1), Q(3), and Q(5) lines of molecular hydrogen are used to calculate a rotational excitation temperature. Comparison of the measured intensity of the Q(2) transition relative to the intensity of Q(1) and Q(3) permitted the retrieval of the ratio of ortho-to-para hydrogen. It is found that an ortho-to-para ratio of between 1.6 and 2.35 is needed to explain the Q-branch line intensity ratios, depending on the excitation model used. This range in ortho-to-para ratios implies a range of molecular hydrogen formation temperature of approximately 105 K to 140 K. 25 refs.

• OSTI ID: 5866940
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 370; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMISTRY
COSMIC RADIO SOURCES
COSMOCHEMISTRY
ELECTROMAGNETIC RADIATION
EMISSION SPECTRA
H2 REGIONS
INFRARED RADIATION
INTERSTELLAR SPACE
PROTOSTARS
RADIATIONS
SPACE
SPECTRA
SPECTROSCOPY
STAR EVOLUTION
STARS