ATOMIUM: Molecular inventory of 17 oxygen-rich evolved stars observed with ALMA^★

¹ Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
e-mail: sofia.wallstrom@kuleuven.be
² School of Physics & Astronomy, Monash University, Wellington Road, Clayton 3800, Victoria, Australia
³ ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Clayton 3800, Australia
⁴ Universität zu Köln, I. Physikalisches Institut, 50937 Köln, Germany
⁵ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
⁶ School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
⁷ School of Chemistry, University of Leeds, Leeds LS2 9JT, UK
⁸ JBCA, Department Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
⁹ Université de Bordeaux, Laboratoire d’Astrophysique de Bordeaux, 33615 Pessac, France
¹⁰ Department of Mathematics, Kiel University, Heinrich-Hecht-Platz 6, 24118 Kiel, Germany
¹¹ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
¹² Departamento de Fisica, Universidad de Santiago de Chile, Av. Victor Jara 3659, Santiago, Chile
¹³ Center for Interdisciplinary Research in Astrophysics and Space Exploration (CIRAS), USACH, Chile
¹⁴ Department of Chemistry and Molecular Biology, University of Gothenburg, Kemigården 4, 412 96 Gothenburg, Sweden
¹⁵ School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA
¹⁶ National Astronomical Research Institute of Thailand, Chiangmai 50180, Thailand
¹⁷ Max-Planck-Institut für Radioastronomie, 53121 Bonn, Germany
¹⁸ National Solar Observatory, Makawao, HI 96790, USA
¹⁹ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 5 place Jules Janssen, 92195 Meudon, France
²⁰ Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
²¹ Université Côte d’Azur, Laboratoire Lagrange, Observatoire de la Côte d’Azur, 06304 Nice Cedex 4, France
²² School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
²³ Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, University Road, Belfast BT7 1NN, UK
²⁴ NASA Goddard Space Flight Center, 8801 Greenbelt Road, Greenbelt, MD 20071, USA
²⁵ Jet Propulsion Laboratory, MS 183-900, California Institute of Technology, Pasadena, CA 91109, USA
²⁶ Department of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands
²⁷ SRON Netherlands Institute for Space Research Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
²⁸ Theoretical Astrophysics, Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
²⁹ Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, 38406 Saint-Martin-d’Hères, France
³⁰ University College London, Department of Physics and Astronomy, London WC1E 6BT, UK

Received: 2 August 2023
Accepted: 27 October 2023

Abstract

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.