Molecular line study of the S-type AGB star W Aquilae: ALMA observations of CS, SiS, SiO and HCN
Artikel i vetenskaplig tidskrift, 2018

Context. With the outstanding spatial resolution and sensitivity of the Atacama Large Millimeter/sub-millimeter Array (ALMA), molecular gas other than the abundant CO can be observed and resolved in circumstellar envelopes (CSEs) around evolved stars, such as the binary S-type asymptotic giant branch (AGB) star W Aquilae.
Aims. We aim to constrain the chemical composition of the CSE and determine the radial abundance distribution, the photospheric peak abundance, and isotopic ratios of a selection of chemically important molecular species in the innermost CSE of W Aql. The derived parameters are put into the context of the chemical evolution of AGB stars and are compared with theoretical models.
Methods. We employ one-dimensional radiative transfer modeling - with the accelerated lambda iteration (ALI) radiative transfer code-of the radial abundance distribution of a total of five molecular species (CS, SiS, (SiS)-Si-30, (SiO)-Si-29 and (HCN)-C-13) and determine the best fitting model parameters based on high-resolution ALMA observations as well as archival single-dish observations. The additional advantage of the spatially resolved ALMA observations is that we can directly constrain the radial profile of the observed line transitions from the observations.
Results. We derive abundances and e-folding radii for CS, SiS, (SiS)-Si-30, (SiO)-Si-29 and (HCN)-C-13 and compare them to previous studies, which are based only on unresolved single-dish spectra. Our results are in line with previous results and are more accurate due to resolution of the emission regions.

stars: winds, outflows

circumstellar matter

submillimeter: stars

stars: abundances

stars: AGB and post-AGB

stars: mass-loss

Författare

M. Brunner

Universität Wien

Taissa Danilovich

KU Leuven

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

S. Ramstedt

Uppsala universitet

Ivan Marti-Vidal

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium, Onsala rymdobservatorium, Observationssupport

Elvire De Beck

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Galaktisk astrofysik

Wouter Vlemmings

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Galaktisk astrofysik

Michael Lindqvist

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium, Onsala rymdobservatorium, Observationssupport

F. Kerschbaum

Universität Wien

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 617 A23

Ämneskategorier

Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik

Annan fysik

Fundament

Grundläggande vetenskaper

Infrastruktur

Onsala rymdobservatorium

DOI

10.1051/0004-6361/201832724

Mer information

Senast uppdaterat

2018-10-05