ATOMIUM: Molecular inventory of 17 oxygen-rich evolved stars observed with ALMA
Journal article, 2024

Context. The dusty winds of cool evolved stars are a major contributor of the newly synthesised material enriching the Galaxy and future generations of stars. However, the details of the physics and chemistry behind dust formation and wind launching have yet to be pinpointed. Recent spatially resolved observations show the importance of gaining a more comprehensive view of the circumstellar chemistry, but a comparative study of the intricate interplay between chemistry and physics is still difficult because observational details such as frequencies and angular resolutions are rarely comparable. Aims. Aiming to overcome these deficiencies, ATOMIUM is an ALMA Large Programme to study the physics and chemistry of the circumstellar envelopes of a diverse set of oxygen-rich evolved stars under homogeneous observing conditions at three angular resolutions between ∼0.02′1.4′. Here we summarize the molecular inventory of these sources, and the correlations between stellar parameters and molecular content. Methods. Seventeen oxygen-rich or S-Type asymptotic giant branch (AGB) and red supergiant (RSG) stars have been observed in several tunings with ALMA Band 6, targeting a range of molecules to probe the circumstellar envelope and especially the chemistry of dust formation close to the star. We systematically assigned the molecular carriers of the spectral lines and measured their spectroscopic parameters and the angular extent of the emission of each line from integrated intensity maps. Results. Across the ATOMIUM sample, we detect 291 transitions of 24 different molecules and their isotopologues. This includes several first detections in oxygen-rich AGB/RSG stars: PO v = 1, SO2 v1 = 1 and v2 = 2, and several high energy H2O transitions. We also find several first detections in S-Type AGB stars: vibrationally excited HCN v2 = 2,3 and SiS v = 4,5,6, as well as first detections of the molecules SiC, AlCl, and AlF in W Aql. Overall, we find strong correlations between the following molecular pairs: CS and SiS, CS and AlF, NaCl and KCl, AlO and SO, SO2 and SO, and SO2 and H2O; meaning both molecules tend to have more detected emission lines in the same sources. The measured isotopic ratios of Si and S are found to be consistent with previous measurements, except for an anomalously high 29Si/30Si ratio of 4 ± 1 in the RSG VX Sgr. Conclusions. This paper presents the overall molecular inventory and an initial analysis of the large ATOMIUM dataset, laying the groundwork for future work deriving molecular abundances and abundance profiles using radiative transfer modeling which will provide more rigorous tests for chemical models.

Instrumentation: interferometers


Stars: AGB and post-AGB

Line: identification


Circumstellar matter


Sofia Wallström

KU Leuven

Taissa Danilovich

KU Leuven

ARC Centre of Excellence for All-sky Astrophysics

Monash University

H. S.P. Müller

University of Cologne

C. A. Gottlieb

Harvard-Smithsonian Center for Astrophysics

S. Maes

KU Leuven

M. Van De Sande

University of Leeds

L. Decin

University of Leeds

KU Leuven

A. M.S. Richards

University of Manchester

A. Baudry

Laboratoire d'Astrophysique de Bordeaux

J. Bolte

University of Kiel

T. Ceulemans

KU Leuven

F. De Ceuster

KU Leuven

A. de Koter

Anton Pannekoek Institute for Astronomy

KU Leuven

I. El Mellah

University of Santiago, Chile

Center for Interdisciplinary Research in Astrophysics and Space Exploration (CIRAS)

M. Esseldeurs

KU Leuven

S. Etoka

University of Manchester

D. Gobrecht

University of Gothenburg

E. Gottlieb

Harvard School of Engineering and Applied Sciences

M. Gray

University of Manchester

National Astronomical Research Institute of Thailand

F. Herpin

Laboratoire d'Astrophysique de Bordeaux

M. Jeste

Max Planck Society

D. Kee

National Solar Observatory

P. Kervella

Paris Observatory

Theo Khouri

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

E. Lagadec

Laboratoire Joseph-Louis Lagrange

J. Malfait

KU Leuven

L. Marinho

Laboratoire d'Astrophysique de Bordeaux

I. McDonald

Open University

University of Manchester

K. M. Menten

Max Planck Society

T. J. Millar

Queen's University Belfast

M. Montargès

Paris Observatory

J. A. Nuth

NASA Goddard Space Flight Center

J. M.C. Plane

University of Leeds

R. Sahai

California Institute of Technology (Caltech)

L. B.F.M. Waters

Netherlands Institute for Space Research (SRON)

Radboud University

K. T. Wong

Uppsala University

Institut de Radioastronomie Millimétrique (IRAM)

J. Yates

University College London (UCL)

A. Zijlstra

University of Manchester

Astronomy and Astrophysics

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

Vol. 681 A50

Subject Categories

Astronomy, Astrophysics and Cosmology



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