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.
<Astrophys. J., 696, 471-483 (2009)>
=2009ApJ...696..471K 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 C2H2,
13C12CH2, CH3, CH4, NH3, 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 (∼1016cm-2) for all the observed molecules
compared to values previously reported and present new results for
CH3 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:
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RA (2000) DE Designation(s)
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23 13 45.4 +61 28 10 NAME NGC 7538 IRS 1 = [M73] B
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 50 293 Observed lines
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Molecule Molecule (1)
10- 19 A10 --- Line Line identification
21- 28 F8.3 cm-1 sigma Wavenumber (1/λ)
30- 36 F7.2 K EJ Energy
38- 50 A13 --- Band Energy band
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Note (1): Only lines that were individually detected at the 3-σ level
are included in this list.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 04-May-2011