SOFIA/EXES Observations of Water Absorption in the Protostar AFGL 2591 at High Spectral Resolution
| Autor: | D. T. Jaffe, Nils Ryde, Graham M. Harper, Curtis DeWitt, William D. Vacca, Mark E. McKelvey, Matthew J. Richter, David A. Neufeld, Adwin Boogert, Nick Indriolo, Kristin Kulas |
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| Rok vydání: | 2015 |
| Předmět: |
Physics
Photosphere Absorption spectroscopy Stratospheric Observatory for Infrared Astronomy FOS: Physical sciences Astronomy and Astrophysics Rotational temperature Astrophysics Astrophysics - Astrophysics of Galaxies Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Protostar Spectral resolution Absorption (electromagnetic radiation) Line (formation) |
| DOI: | 10.48550/arxiv.1502.06611 |
| Popis: | We present high spectral resolution (~3 km/s) observations of the nu_2 ro-vibrational band of H2O in the 6.086--6.135 micron range toward the massive protostar AFGL 2591 using the Echelon-Cross-Echelle Spectrograph (EXES) on the Stratospheric Observatory for Infrared Astronomy (SOFIA). Ten absorption features are detected in total, with seven caused by transitions in the nu_2 band of H2O, two by transitions in the first vibrationally excited nu_2 band of H2O, and one by a transition in the nu_2 band of H2{18}O. Among the detected transitions is the nu_2 1(1,1)--0(0,0) line which probes the lowest lying rotational level of para-H2O. The stronger transitions appear to be optically thick, but reach maximum absorption at a depth of about 25%, suggesting that the background source is only partially covered by the absorbing gas, or that the absorption arises within the 6 micron emitting photosphere. Assuming a covering fraction of 25%, the H2O column density and rotational temperature that best fit the observed absorption lines are N(H2O)=(1.3+-0.3)*10^{19} cm^{-2} and T=640+-80 K. Comment: 6 pages, 3 figures, 1 table, accepted for publication in ApJL |
| Databáze: | OpenAIRE |
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