J/MNRAS/437/532 VY CMa molecular line spectra (Matsuura+, 2014)
Herschel SPIRE and PACS observations of the red supergiant VY CMa:
analysis of the molecular line spectra.
Matsuura M., Yates J.A., Barlow M.J., Swinyard B.M., Royer P.,
Cernicharo J., Decin L., Wesson R., Polehampton E.T., Blommaert J.A.D.L.,
Groenewegen M.A.T., Van De Steene G.C., van Hoof P.A.M.
<Mon. Not. R. Astron. Soc., 437, 532-546 (2014)>
=2014MNRAS.437..532M 2014MNRAS.437..532M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, supergiant ; Spectroscopy
Keywords: radiative transfer - stars: individual: VY CMa - stars: mass-loss -
ISM: molecules - infrared: stars - submillimetre: stars
Abstract:
We present an analysis of the far-infrared and submillimetre molecular
emission-line spectrum of the luminous M-supergiant VY CMa, observed
with the Spectral and Photometric Imaging Receiver (SPIRE) and
Photodetector Array Camera and Spectrometer for Herschel spectrometers
aboard the Herschel Space Observatory. Over 260 emission lines were
detected in the 190-650µm SPIRE Fourier Transform Spectrometer
spectra, with one-third of the observed lines being attributable to
H2O. Other detected species include CO, 13CO, H2O, SiO, HCN, SO,
SO2, CS, H2S and NH3. Our model fits to the observed 12CO and
13CO line intensities yield a 12C/13C ratio of 5.6±1.8,
consistent with measurements of this ratio for other M-supergiants,
but significantly lower than previously estimated for VY CMa from
observations of lower-J lines. The spectral line energy distribution
for 20 SiO rotational lines shows two temperature components: a hot
component at ∼1000K, which we attribute to the stellar atmosphere and
inner wind, plus a cooler ∼200K component, which we attribute to an
origin in the outer circumstellar envelope. We fit the line fluxes of
12CO, 13CO, H2O and SiO, using the smmol non-local thermodynamic
equilibrium (LTE) line transfer code, with a mass-loss rate of
1.85x10-4M☉/yr between 9R* and 350R*. We also fit the observed
line fluxes of 12CO, 13CO, H2O and SiO with smmol non-LTE line
radiative transfer code, along with a mass-loss rate of
1.85x10-4M☉/yr. To fit the high rotational lines of CO and
H2O, the model required a rather flat temperature distribution
inside the dust condensation radius, attributed to the high H2O
opacity. Beyond the dust condensation radius the gas temperature is
fitted best by an r-0.5 radial dependence, consistent with the coolant
lines becoming optically thin. Our H2O emission-line fits are
consistent with an ortho:para ratio of 3 in the outflow.
Description:
The Herschel Space Observatory (hereafter Herschel) was launched in
2009 May with three instruments on board: SPIRE, PACS and HIFI . We
report here observations made with the SPIRE Fourier Transform
Spectrometer (FTS) and with the PACS grating spectrometer, which
together cover the wavelength range from 55 to 650um. The SPIRE FTS
covers the 190-650um wavelength range, simultaneously, while the PACS
spectrometer covers the 55-210um spectral range, similar to that
covered by the Long Wavelength Spectrometer (LWS) on board the
Infrared Space Observatory (ISO), although with higher spectral
resolution and greater sensitivity.
Objects:
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RA (2000) DE Designation(s)
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07 22 58.33 -25 46 03.2 VY CMa = V* VY CMa
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea2.dat 119 170 VY CMa line fluxes and identifications (IDs) in
the SPIRE FTS SLW spectra
tablea3.dat 121 288 VY CMa: Line fluxes and identifications in the
SPIRE FTS SSW spectra
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See also:
J/ApJS/190/348 : 1mm spectral survey of IRC+10216 + VY CMa (Tenenbaum+, 2010)
J/A+A/551/A113 : Spectrum of VY CMa in 220.65-224.25GHz range (Kaminski+, 2013)
Byte-by-byte Description of file: tablea2.dat tablea3.dat
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Bytes Format Units Label Explanations
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1- 6 F6.3 cm-1 nuobs1 ? Observed wavenumber (OD123)
8- 13 F6.1 10-18W/m2 F1 ? VY CMa line flux (OD123)
15- 19 F5.1 10-18W/m2 e_F1 ? rms uncertainty on F1 (1)
21- 26 F6.3 cm-1 nuobs2 ? Observed wavenumber (OD317)
27 A1 --- u_nuobs2 [?] Uncertainty flag on nuobs2
29- 33 F5.3 cm-1 e_nuobs2 ? rms uncertainty on nuobs2 (1)
35- 40 F6.1 10-18W/m2 F2 ? VY CMa line flux (OD317)
42- 46 F5.1 10-18W/m2 e_F2 ? rms uncertainty on F2
48 A1 --- n_nu0 [+] for blend (2)
49- 54 F6.3 cm-1 nu0 ? Vacuum wavenumber
55 A1 --- u_nu0 [?] Uncertainty flag on nu0
57- 63 F7.2 GHz Fnu0 ? Vacuum frequency
65- 70 F6.2 um lambda0 ? Vacuum wavelength
71 A1 --- u_lambda0 [?] Uncertainty flag on lambda0
73- 82 A10 --- Species Species
84-121 A38 ---- Trans Transition (3)
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Note (1): The listed uncertainties for the line fluxes are those from the line
fitting.
Note (2): An ID row beginning with a '+' indicates that the line is blended
with that on the row above.
Note (3): The quantum numbers are J except where stated.
H2O transitions are given in the format JKa'Kc'-JKaKc.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 10-Mar-2015