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SOFIA/EXES observations of water absorption in the protostar AFGL 2591 at high spectral resolution

Indriolo, Nick; Neufeld, D. A.; DeWitt, C. N.; Richter, M. J.; Boogert, A. C. A.; Harper, G. M.; Jaffe, D. T.; Kulas, K. R.; McKelvey, M. E. and Ryde, Nils LU , et al. (2015) In Astrophysical Journal Letters 802(2).
Abstract
We present high spectral resolution (similar to 3 km s(-1)) observations of the nu(2) ro-vibrational band of H2O in the 6.086-6.135 mu m 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 (H2O)-O-18. Among the detected transitions is the nu(2) 1(1,1)-0(0,0) line that probes the lowest-lying rotational level of para-H2O. The stronger transitions appear to be optically thick, but reach maximum absorption at a... (More)
We present high spectral resolution (similar to 3 km s(-1)) observations of the nu(2) ro-vibrational band of H2O in the 6.086-6.135 mu m 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 (H2O)-O-18. Among the detected transitions is the nu(2) 1(1,1)-0(0,0) line that 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 mu m 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) x 10(19) cm(-2) and T = 640 +/- 80 K. (Less)
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subject
keywords
stars: protostars
in
Astrophysical Journal Letters
volume
802
issue
2
publisher
University of Chicago Press
external identifiers
  • wos:000352138300001
  • scopus:84926637284
ISSN
2041-8213
DOI
10.1088/2041-8205/802/2/L14
language
English
LU publication?
yes
id
a3592111-ef61-40c1-9e10-9d66e9cc4cd1 (old id 5402861)
date added to LUP
2015-05-19 14:10:07
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2017-01-01 03:39:59
@article{a3592111-ef61-40c1-9e10-9d66e9cc4cd1,
  abstract     = {We present high spectral resolution (similar to 3 km s(-1)) observations of the nu(2) ro-vibrational band of H2O in the 6.086-6.135 mu m 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 (H2O)-O-18. Among the detected transitions is the nu(2) 1(1,1)-0(0,0) line that 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 mu m 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) x 10(19) cm(-2) and T = 640 +/- 80 K.},
  articleno    = {L14},
  author       = {Indriolo, Nick and Neufeld, D. A. and DeWitt, C. N. and Richter, M. J. and Boogert, A. C. A. and Harper, G. M. and Jaffe, D. T. and Kulas, K. R. and McKelvey, M. E. and Ryde, Nils and Vacca, W.},
  issn         = {2041-8213},
  keyword      = {stars: protostars},
  language     = {eng},
  number       = {2},
  publisher    = {University of Chicago Press},
  series       = {Astrophysical Journal Letters},
  title        = {SOFIA/EXES observations of water absorption in the protostar AFGL 2591 at high spectral resolution},
  url          = {http://dx.doi.org/10.1088/2041-8205/802/2/L14},
  volume       = {802},
  year         = {2015},
}