J/A+A/615/A8 APEX spectrum of R Dor (159.0-368.5GHz) (De Beck+, 2018)
Circumstellar environment of the M-type AGB star R Doradus.
APEX spectral scan at 159.0-368.5 GHz.
De Beck E., Olofsson H.
<Astron. Astrophys. 615, A8 (2018)>
=2018A&A...615A...8D 2018A&A...615A...8D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Spectroscopy
Keywords: stars: AGB and post-AGB - stars: individual: R Dor -
stars: mass loss - astrochemistry
Abstract:
Our current insights into the circumstellar chemistry of asymptotic
giant branch (AGB) stars are largely based on studies of carbon-rich
stars and stars with high mass-loss rates.
In order to expand the current molecular inventory of evolved stars we
present a spectral scan of the nearby, oxygen-rich star R Dor, a star
with a low mass-loss rate (∼2x10-7M☉/yr).
We carried out a spectral scan in the frequency ranges 159.0-321.5GHz
and 338.5-368.5GHz (wavelength range 0.8-1.9mm) using the SEPIA/Band-5
and SHeFI instruments on the APEX telescope and we compare it to
previous surveys, including one of the oxygen-rich AGB star IK Tau,
which has a high mass-loss rate (∼5x10-6M☉/yr).
The spectrum of R Dor is dominated by emission lines of SO2 and the
different isotopologues of SiO. We also detect CO, H2O, HCN, CN, PO,
PN, SO, and tentatively TiO2, AlO, and NaCl. Sixteen out of
approximately 320 spectral features remain unidentified. Among these
is a strong but previously unknown maser at 354.2GHz, which we suggest
could pertain to H2SiO, silanone. With the exception of one, none of
these unidentified lines are found in a similarly sensitive survey of
IK Tau performed with the IRAM 30 m telescope. We present radiative
transfer models for five isotopologues of SiO (28SiO, 29SiO,
30SiO, Si17O, Si18O), providing constraints on their fractional
abundance and radial extent. We derive isotopic ratios for C, O, Si,
and S and estimate that, based on our results for 17O/18O, R Dor
likely had an initial mass in the range 1.3-1.6M☉, in agreement
with earlier findings based on models of H2O line emission. From the
presence of spectral features recurring in many of the measured
thermal and maser emission lines we tentatively identify up to five
kinematical components in the outflow of R Dor, indicating deviations
from a smooth, spherical wind.
Description:
The FITS file RDorAPEXTA_DeBeck2018.fits contains the fully reduced
spectrum of R Dor in the range 159.0-368.5GHz obtained with APEX. The
intensity is given in corrected antenna temperature, TA*, as
described in Sect. 2 of the paper.
Objects:
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RA (2000) DE Designation(s)
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04 36 45.59 -62 04 37.8 R Dor = HR 1492
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 195 1 Information on fist spectrum
sp/* . 1 Fits spectrum
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 26 I7 --- Nx Number of pixels along X-axis
28- 50 A23 --- Obs.date Observation date (YYYY-MM-DDThh:mm:ss.sss)
52- 63 E12.5 Hz bFreq Lower value of frequency interval
65- 75 E11.5 Hz BFreq Upper value of frequency interval
77- 82 I6 Hz dFreq spectral resolution
84- 87 I4 Kibyte size Size of FITS file
89-116 A28 --- FileName Name of FITS file, in subdirectory sp
118-195 A78 --- Title Title of the FITS file
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Acknowledgements:
Elvire De Beck, elvire.debeck(at)chalmers.se
(End) Patricia Vannier [CDS] 24-Jan-2018