J/ApJ/696/471 MIR spectroscopy of NGC 7538 IRS 1 (Knez+, 2009) ================================================================================ High-resolution mid-infrared spectroscopy of NGC 7538 IRS 1: probing chemistry in a massive young stellar object. Knez C., Lacy J.H., Evans N.J., van Dishoeck E.F., Richter M.J. =2009ApJ...696..471K ================================================================================ ADC_Keywords: YSOs ; Line Profiles ; Infrared sources ; Spectroscopy ; H II regions Keywords: H II regions - infrared: ISM - ISM: individual (NGC 7538 IRS 1) - ISM: molecules Abstract: We present high-resolution (R=75000-100000) mid-infrared spectra of the high-mass embedded young star IRS 1 in the NGC 7538 star-forming region. Absorption lines from many rotational states of C_2_H_2_, ^13^C^12^CH_2_, CH_3_, CH_4_, NH_3_, HCN, HNCO, and CS are seen. The gas temperature, column density, covering factor, line width, and Doppler shift for each molecule are derived. All molecules were fit with two velocity components between -54 and -63km/s. We find high column densities (~10^16^cm^-2^) for all the observed molecules compared to values previously reported and present new results for CH_3_ and HNCO. Several physical and chemical models are considered. The favored model involves a nearly edge-on disk around a massive star. Radiation from dust in the inner disk passes through the disk atmosphere, where large molecular column densities can produce the observed absorption line spectrum. Description: The observations were made with TEXES, the Texas Echelon Cross Echelle Spectrograph, on the NASA Infrared Telescope Facility (IRTF) in 2001 June and November, 2002 September and December, and 2005 December. Objects: ------------------------------------------------------ RA (2000) DE Designation(s) ------------------------------------------------------ 23 13 45.4 +61 28 10 NAME NGC 7538 IRS 1 = [M73] B ------------------------------------------------------ File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 50 293 Observed lines -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- Molecule Molecule (1) 10- 19 A10 --- Line Line identification 21- 28 F8.3 cm-1 sigma Wavenumber (1/{lambda}) 30- 36 F7.2 K EJ Energy 38- 50 A13 --- Band Energy band -------------------------------------------------------------------------------- Note (1): Only lines that were individually detected at the 3-{sigma} level are included in this list. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 04-May-2011