INFRARED ABSORPTION LINES TOWARD NGC 7538 IRS 1: ABUNDANCES OF H{sub 2}, H{sub 3}{sup +}, AND CO
- Universitäts-Sternwarte München, Scheinerstr. 1, D-81679 Munich (Germany)
- Gemini Observatory, 670 North A‘ohoku Place, Hilo, HI 96720 (United States)
- Subaru Telescope, 650 North A‘ohoku Place, Hilo, HI 96720 (United States)
We report high-resolution near-infrared absorption spectroscopy of H{sub 2}, H{sub 3}{sup +}, and CO toward the young high mass object NGC 7538 IRS 1. The v = 1–0 H{sub 2} S(0) line and lines in the CO v = 2–0 band were detected; the v = 1–0 H{sub 2} S(1) line and the v = 1–0 H{sub 3}{sup +} lines [R(1, 1){sup l}, R(1, 0), R(1, 1){sup u}] were not detected. The line of sight traverses two clouds, with temperatures 45 and 259 K and with roughly equal column densities of CO. Assuming that H{sub 2} is at the same temperature as CO and that the two species are uniformly mixed, [H{sub 2}]/[CO] = 3600 ± 1200. NGC 7538 is the most distant object from the Galactic center for which [H{sub 2}]/[CO] has been directly measured using infrared absorption spectroscopy.
- OSTI ID:
- 22522325
- Journal Information:
- Astrophysical Journal, Vol. 806, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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