J/A+A/658/A135 RS Cnc IRAM NOEMA interferometric data (Winters+, 2022)
Molecules, shocks, and disk in the axi-symmetric wind of the MS-type AGB star
RS Cancri.
Winters J.M., Hoai D.T., Wong K.T., Kim W.-J., Nhung P.T., Tuan-Anh P.,
Lesaffre P., Darriulat P., Le Bertre T.
<Astron. Astrophys. 658, A135 (2022)>
=2022A&A...658A.135W 2022A&A...658A.135W (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Stars, late-type ; Interferometry ; Mass loss ;
Radio lines
Keywords: stars: AGB and post-AGB, circumstellar matter - stars: mass-loss -
stars: winds, outflows - stars: individual: RS Cnc -
radio lines: stars
Abstract:
The latest evolutionary phases of low- and intermediate mass stars are
characterized by complex physical processes like turbulence,
convection, stellar pulsations, magnetic fields, condensation of solid
particles, and the formation of massive outflows that inject freshly
produced heavy elements and dust particles into the interstellar
medium.
By investigating individual objects in detail we wish to analyze and
disentangle the effects of the interrelated physical processes on the
structure of the wind forming region around these objects. We use the
Northern Extended Millimeter Array (NOEMA) to obtain spatially and
spectrally resolved observations of the semi-regular Asymptotic Giant
Branch star RS Cancri to shed light on the morpho-kinematic structure
of its inner, wind forming environment by applying detailed 3-D
reconstruction modeling and LTE radiative transfer calculations.
We detect 32 lines of 13 molecules and isotopologs (CO, SiO, SO,
SO2, H2O, HCN, PN), including several transitions from
vibrationally excited states. HCN, H13CN, millimeter vibrationally
excited H2O, SO, 34SO, SO2, and PN are detected for the first
time in RS Cnc. Evidence for rotation is seen in HCN, SO, SO2, and
SiO(v=1). From CO and SiO channel maps, we find an inner, equatorial
density enhancement, and a bipolar outflow structure with a mass loss
rate of 1x10-7M☉/yr for the equatorial region and of
2x10-7M☉/yr for the polar outflows. The 12CO/13CO ratio is
measured to be ∼20 on average, 24±2 in the polar outflows and 19±3
in the equatorial region. We do not find direct evidence of a
companion that might explain this kind of kinematic structure, and
explore the possibility that a magnetic field might be the cause of
it. The innermost molecular gas is influenced by stellar pulsation and
possibly by convective cells that leave their imprint on broad wings
of certain molecular lines, such as SiO and SO.
RS Cnc is one of the few nearby, low mass-loss-rate, oxygen-rich AGB
stars with a wind displaying both an equatorial disk and bipolar
outflows. Its orientation with respect to the line of sight is
particularly favorable for a reliable study of its morpho-kinematics.
The mechanism causing early spherical symmetry breaking remains
however uncertain, calling for additional high spatial and spectral
resolution observations of the emission of different molecules in
different transitions, along with a deeper investigation of the
coupling among the different physical processes at play.
Description:
We have obtained spectral maps of different molecules in RS Cnc, a
prototypical source with composite CO profiles. Interferometric data
were acquired with the IRAM NOEMA array and combined with on-the-fly
maps obtained at the IRAM 30m for the CO lines. The resulting data
cubes cover a field of 22x22arcsec2 with spectral resolutions
between 0.1km/s and 3km/s and with synthesized beams of the order of
0.4"x0.4". The FITS files presented here contain frequency-integrated
spectral data cubes. Each map typically contains 1024x1024 pixels of a
size of about 0.08x0.08arcsec2.
Objects:
-----------------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------------
09 10 38.80 +30 57 47.3 RS Cnc = HD 78712
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 118 37 List of fits maps
fits/* . 37 Individual fits maps
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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- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 33 I4 Kibyte size Size of FITS file
35- 68 A34 --- FileName Name of FITS file, in subdirectory fits
70-118 A49 --- Title Title of the FITS file
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Acknowledgements:
Jan Martin Winters, winters(at)iram.fr
(End) Patricia Vannier [CDS] 08-Dec-2021