J/ApJ/935/165 AFGL 2591 and AFGL 2136 v=1-0 and v=2-1 transition (Barr+, 2022)
Infrared H2O Absorption in Massive Protostars at High Spectral Resolution:
Full Spectral Survey Results of AFGL 2591 and AFGL 2136.
Barr A.G., Boogert A., Li J., DeWitt C.N., Montiel E., Richter M.J.,
Indriolo N., Pendleton Y., Chiar J., Tielens A.G.G. M
<Astrophys. J., 935, 165 (2022)>
=2022ApJ...935..165B 2022ApJ...935..165B
ADC_Keywords: Star Forming Region; YSOs ; Spectra, infrared
Keywords: Star formation ; Water vapor ; Circumstellar disks ;
Protoplanetary disks ; Stellar accretion disks ; Chemical
abundances ; Astrochemistry
Abstract:
We have performed a high-resolution 4-13µm spectral survey of the
hot molecular gas associated with the massive protostars AFGL-2591 and
AFGL-2136. Here we present the results of the analysis of the ν2
band of H2O, detected with the Echelon Cross Echelle Spectrograph on
board the Stratospheric Observatory for Infrared Astronomy between
wavelengths of 5 and 8µm. All lines are seen in absorption.
Rotation diagrams indicate that the gas is optically thick and lines
are observed to saturate at 40% and 15% relative to the continuum for
AFGL 2136 and AFGL 2591, respectively. We applied two curve of growth
analyses to derive the physical conditions, one assuming a foreground
origin and one a circumstellar disk origin. We find temperatures of
400-600K. A foreground origin would require the presence of externally
heated clumps that are smaller than the continuum source. The disk
analysis is based on stellar atmosphere theory, which takes into
consideration the temperature gradient in the disk. We discuss the
challenges with each model, taking into consideration the properties
of other species detected in the spectral survey, and conclude that
further modeling efforts are required to establish whether the
absorption has a disk or foreground origin. The main challenge to the
foreground model is that molecules are expected to be observed in
emission. The main challenges to the disk model are the midplane
heating mechanism and the presence of narrow absorption lines shifted
from the systemic velocity.
Description:
AFGL 2591 and AFGL 2136 were observed with the Echelon Cross Echelle
Spectrograph (EXES) spectrometer on board the SOFIA flying observatory
as part of SOFIA programs 05_0041 and 06_0117. In this full spectral
survey of AFGL 2591 and AFGL 2136, EXES covered the range of 5.3-8um.
Objects:
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RA (2000) DE Designation(s)
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20 29 24.82 +40 11 19.5 AFGL2591 = 2MASS J20292486+4011194
18 22 26.52 -13 30 14.0 AFGL2136 = AGAL G017.637+00.154
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 84 153 *Line Parameters for the v=1-0 transition of
AFGL 2136
table5.dat 84 55 *Line Parameters for the v=2-1 transition of
AFGL 2136
table7.dat 84 177 *Line Parameters for the v=1-0 transition of
AFGL 2591
table8.dat 84 63 *Line Parameters for the v=2-1 transition of
AFGL 2591
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Note on table*.dat: Line data were taken from the HITRAN database
(Gordon+, 2017JQSRT.203....3G 2017JQSRT.203....3G).
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See also:
J/ApJ/606/L73 : CO emission of 5 Herbig Ae stars (Blake+, 2004)
J/A+A/492/257 : Collisional excitation of water in warm media (Faure+, 2008)
J/ApJ/696/471 : MIR spectroscopy of NGC 7538 IRS 1 (Knez+, 2009)
J/A+A/558/A24 : The VLTI/MIDI survey of Massive YSOs (Boley+, 2013)
J/A+A/620/A31 : ALMA maps of G17.64+0.16 (Maud+, 2018)
J/A+A/627/L6 : ALMA Long Baseline maps of G17.64+0.16 (Maud+, 2019)
J/ApJ/900/104 : IR high-res. sp. hot cores of AFGL2591 & AFGL2136 (Barr+, 2020)
J/A+A/655/A84 : AFGL 2591-VLA 3 IRAM/NOEMA datacubes (Suri+, 2021)
Byte-by-byte Description of file: table[4578].dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Trans Transition
21- 26 F6.4 um Wave Wavelength
28- 31 I4 K El Lower level energy
33- 34 I2 --- gl Lower level statistical weight
36- 37 I2 --- gu Upper level statistical weight
39- 42 F4.1 s-1 Aul Einstein coefficient
44- 48 F5.1 km/s VLSR Peak line Local Standard of Rest velocity
50- 52 F3.1 km/s e_VLSR Uncertainty in VLSR
54- 57 F4.1 km/s FWHM Full-Width at Half Maximum of line
59- 61 F3.1 km/s e_FWHM Uncertainty in FWHM
63- 67 F5.2 10+8Hz EW Equivalent width of line
69- 72 F4.2 10+8Hz e_EW Uncertainty in W
74- 78 F5.2 [-] logeta0 log lower level opacity (1)
80- 84 F5.2 [-] logtau0 log peak optical depth
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Note (1): Of the transition calculated for ε = 0.5
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 07-Jun-2024