An ALMA view of SO and SO${}_2$ around oxygen-rich AGB stars

Abstract

We present and analyse SO and SO${}_2$, recently observed with high angular resolution and sensitivity in a spectral line survey with ALMA, for two oxygen-rich AGB stars: the low mass-loss rate R Dor and high mass-loss rate IK Tau. We analyse 8 lines of SO detected towards both stars, 78 lines of SO${}_2$detected towards R Dor and 52 lines of SO${}_2$ detected towards IK Tau. We detect several lines of ${}^{34}$SO, ${}^{33}$SO and ${}^{34}$SO${}_2$ towards both stars, and tentatively S${}^{18}$O towards R Dor, and hence derive isotopic ratios for these species. The spatially resolved observations show us that the two sulphur oxides are co-located towards R Dor and trace out the same wind structures in the circumstellar envelope (CSE). Much of the emission is well reproduced with a Gaussian abundance distribution spatially centred on the star. Emission from the higher energy levels of SO and SO${}_2$ towards R Dor provide evidence in support of a rotating inner region of gas identified in earlier work. The new observations allow us to refine the abundance distribution of SO in IK Tau derived from prior observations with single antennas, and confirm the distribution is shell-like with the peak in the fractional abundance not centred on the star. The confirmation of different types of SO abundance distributions will help fine-tune chemical models and allows for an additional method to discriminate between low and high mass-loss rates for oxygen-rich AGB stars.

arXiv commentAccepted for publication in MNRAS

References in corpus (21)

• The chemical composition of the Sun
• The Cologne Database for Molecular Spectroscopy, CDMS, in the Virtual Atomic and Molecular Data Centre, VAMDC
• A close halo of large transparent grains around extreme red giant stars
• The millimeter IRAM-30m line survey toward IK Tau
• Mode switching in the nearby Mira-like variable R Doradus
• Circumstellar molecular composition of the oxygen-rich AGB star IK~Tau: II. In-depth non-LTE chemical abundance analysis
• Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tau as seen by Herschel/HIFI
• ALMA spectral line and imaging survey of a low and a high mass-loss rate AGB star between 335 and 362 GHz
• Sulphur molecules in the circumstellar envelopes of M-type AGB stars
• A HIFI view on circumstellar H2O in M-type AGB stars: radiative transfer, velocity profiles, and H2O line cooling
• Determining the effects of clumping and porosity on the chemistry in a non-uniform AGB outflow
• Sulphur-bearing molecules in AGB stars I: The occurrence of hydrogen sulfide
• Sulphur-bearing molecules in AGB stars II: Abundances and distributions of CS and SiS
• Circumstellar molecular composition of the oxygen-rich AGB star IK Tau: I. Observations and LTE chemical abundance analysis
• ALMA detection of a tentative nearly edge-on rotating disk around the nearby AGB star R~Doradus
• The Role of Internal Photons on the Chemistry of the Circumstellar Envelopes of AGB Stars
• An ALMA view of CS and SiS around oxygen-rich AGB stars
• First detection of photospheric depletion in the LMC
• Water isotopologues in the circumstellar envelopes of M-type AGB stars
• Molecular line study of the S-type AGB star W Aquilae. ALMA observations of CS, SiS, SiO and HCN
• The Evolution Of Carbon, Sulphur, and Titanium Isotopes from High-Redshift to the Local Universe

Cited by in corpus (14)

• ATOMIUM: ALMA tracing the origins of molecules in dust forming oxygen rich M-type stars: Motivation, sample, calibration, and initial results
• The impact of stellar companion UV photons on the chemistry of the circumstellar environments of AGB stars
• The abundance of S- and Si-bearing molecules in O-rich circumstellar envelopes of AGB stars
• Rotational spectra of vibrationally excited AlO and TiO in oxygen rich stars
• ATOMIUM: Molecular inventory of 17 oxygen-rich evolved stars observed with ALMA
• Morpho-kinematics of the circumstellar envelope of the AGB star R Dor: a global view
• The unusual 3D distribution of NaCl around the AGB star IK Tau
• Molecules, shocks, and disk in the axi-symmetric wind of the MS-type AGB star RS Cancri
• Sensitivity study of chemistry in AGB outflows using chemical kinetics
• Evidence for episodic and patchy mass ejection in the circumstellar envelope of AGB star R Leonis
• High-angular-resolution ALMA imaging of the inhomogeneous dynamical atmosphere of the asymptotic giant branch star W Hya
• Molecules and Chemistry in Red Supergiants
• Probing sulfur chemistry in oxygen-rich AGB stars with ALMA
• Discovery of sulfur oxides in the ejecta of a B[e] supergiant