ATOMIUM: Continuum emission and evidence of dust enhancement from binary motion
Journal article, 2025
Context. Low- and intermediate-mass stars on the asymptotic giant branch (AGB) account for a significant portion of the dust and chemical enrichment in their host galaxy. Understanding the dust formation process of these stars and their more massive counterparts, the red supergiants, is essential for quantifying galactic chemical evolution. Aims. To improve our understanding of the dust nucleation and growth process, we aim to better constrain stellar properties at millimetre wavelengths. To characterise how this process varies with the mass-loss rate and pulsation period, we studied a sample of oxygen-rich and S-type evolved stars. Methods. Here we present ALMA observations of the continuum emission around a sample of 17 stars from the ATOMIUM survey. We analysed the stellar parameters at 1.24 mm and the dust distributions at high angular resolutions. Results. From our analysis of the stellar contributions to the continuum flux, we find that the semi-regular variables all have smaller physical radii and fainter monochromatic luminosities than the Mira variables. Comparing these properties with pulsation periods, we find a positive trend between the stellar radius and period only for the Mira variables with periods of more than 300 days, and we find and a positive trend between the period and the monochromatic luminosity only for the red supergiants and the most extreme AGB stars with periods of more than 500 days. We find that the continuum emission at 1.24 mm can be classified into four groups; (i) ‘featureless’ continuum emission is confined to the (unresolved) regions close to the star for five stars in our sample, (ii) relatively uniform extended flux is seen for four stars, (iii) tentative elongated features are seen for three stars, and (iv) the remaining five stars have unique or unusual morphological features in their continuum maps. These features can be explained by the fact that 10 of the 14 AGB stars in our sample have binary companions. Conclusions. Based on our results, we conclude that there are two modes of dust formation: well-established pulsation-enhanced dust formation and our newly proposed companion-enhanced dust formation. If the companion is located close to the AGB star, in the wind acceleration region, then additional dust formed in the wake of the companion can increase the amount of mass lost through the dust-driven wind. This explains the different dust morphologies seen around our stars and partly accounts for the large scatter in literature mass-loss rates, especially among semi-regular stars with small pulsation periods.
circumstellar matter
submillimeter: stars
stars: AGB and post-AGB
Author
Taissa Danilovich
KU Leuven
Monash University
N. Samaratunge
Monash University
Y. L. Mori
Monash University
A.M.S. Richards
University of Manchester
A. Baudry
Laboratoire d'Astrophysique de Bordeaux
S. Etoka
University of Manchester
M. Montargès
Paris Observatory
P. Kervella
Paris Observatory
University of Chile (UCH)
I. McDonald
University of Manchester
C. A. Gottlieb
Harvard-Smithsonian Center for Astrophysics
A. Wallace
Monash University
D. J. Price
Monash University
L. Decin
University of Leeds
KU Leuven
J. Bolte
University of Kiel
T. Ceulemans
KU Leuven
F. De Ceuster
KU Leuven
A. de Koter
Anton Pannekoek Institute for Astronomy
KU Leuven
D. Dionese
University of Warsaw
Université libre de Bruxelles (ULB)
I. El Mellah
University of Santiago, Chile
M. Esseldeurs
KU Leuven
M. Gray
University of Manchester
National Astronomical Research Institute of Thailand
F. Herpin
Laboratoire d'Astrophysique de Bordeaux
Theo Khouri
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
E. Lagadec
Laboratoire Joseph-Louis Lagrange
C. Landri
KU Leuven
L. Marinho
Spanish National Research Council (CSIC)
Laboratoire d'Astrophysique de Bordeaux
K. Menten
Max Planck Society
T.J. Millar
Queen's University Belfast
H. S.P. Müller
University of Cologne
B. Pimpanuwat
National Astronomical Research Institute of Thailand
J. M. C. Plane
University of Leeds
R. Sahai
California Institute of Technology (Caltech)
L. Siess
Université libre de Bruxelles (ULB)
M. Van De Sande
Leiden University
O. Vermeulen
KU Leuven
K. T. Wong
Uppsala University
J. A. Yates
University College London (UCL)
A. Zijlstra
University of Manchester
Macquarie University
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 704 A341Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202554878