Esseldeurs, M., Mathis, S., & Decin, L. (2026). The fate of Earth during the Sun’s giant phases: New constraints from ab initio tidal modelling and AGB mass loss. Astronomy & Astrophysics, 710, L26.
@article{Esseldeurs2026c,
author = {{Esseldeurs}, M. and {Mathis}, S. and {Decin}, L.},
title = {{The fate of Earth during the Sun's giant phases: New constraints from ab initio tidal modelling and AGB mass loss}},
journal = {Astronomy & Astrophysics},
keywords = {methods: numerical, Earth, planet-star interactions, binaries: close, stars: evolution, planetary systems},
year = {2026},
month = jun,
volume = {710},
eid = {L26},
pages = {L26},
doi = {10.1051/0004-6361/202660576},
adsurl = {https://ui.adsabs.harvard.edu/abs/2026A&A...710L..26E},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Context: The long-term evolution of planetary systems around solar-type stars is governed by the interplay between stellar expansion, tidal interactions, and mass loss during the red giant branch (RGB) and asymptotic giant branch (AGB) phases. However, tidal dissipation efficiencies and AGB mass-loss rates both remain poorly constrained, leading to significant uncertainty in predicting the fate of planetary systems, in particular, that of the Earth orbiting the ageing Sun.
Aims: We reassess the survival of the Earth and the inner Solar System planets during the post-main-sequence evolution of the Sun, focusing on the impact of updated tidal dissipation prescriptions and varying AGB mass-loss rates.
Methods: We modelled the orbital evolution of the Earth using stellar evolution tracks for a solar-mass star that incorporate the most recent tidal dissipation prescriptions derived from ab initio calculations. We compared these results with outcomes obtained using previously published and commonly adopted tidal prescriptions, and we explored a range of AGB mass-loss rates.
Results: We find that the predicted fate of the Earth is highly sensitive to the tidal model and the assumed mass-loss rate. Based on updated tidal dissipation prescriptions, Earth survives the RGB and AGB phases of the Sun. In contrast, the use of earlier prescriptions of tidal dissipation prescriptions leads to engulfment during the AGB phase. Furthermore, low AGB mass-loss rates result in engulfment, and vice versa. Using the observed mass-loss rates of the AGB star L2 Pup as a proxy for the Sun’s future AGB mass-loss rate results in the survival of the Earth during the AGB phase when combined with our tidal dissipation evaluation.
Conclusions: Currently, the survival of the Earth and the inner Solar System is not robustly determined and critically depends on the treatment of tidal dissipation and stellar mass loss. Given the current observational uncertainties in AGB mass-loss rates, the ultimate fate of the Earth remains uncertain, highlighting the need for improved constraints on the late-stages of stellar evolution. However, considering observational proxies for the Sun during the AGB phase, it is likely that the Earth will survive the Sun’s red giant phase.
Esseldeurs, M., Ahuir, J., Amard, L., Mathis, S., & Decin, L. (2026). Competition between gravity waves excited by convection and tides in stars that host a companion. Astronomy & Astrophysics, 709, A49.
@article{Esseldeurs2026b,
author = {{Esseldeurs}, M. and {Ahuir}, J. and {Amard}, L. and {Mathis}, S. and {Decin}, L.},
title = {{Competition between gravity waves excited by convection and tides in stars that host a companion}},
journal = {Astronomy & Astrophysics},
keywords = {waves, methods: numerical, planet-star interactions, binaries: close, stars: evolution, planetary systems, Solar and Stellar Astrophysics, Earth and Planetary Astrophysics},
year = {2026},
month = may,
volume = {709},
eid = {A49},
pages = {A49},
doi = {10.1051/0004-6361/202558219},
archiveprefix = {arXiv},
eprint = {2603.26577},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2026A&A...709A..49E},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Context: Asteroseismology has become a powerful diagnostic tool in stellar astrophysics, offering unprecedented insights into the internal structures and dynamics of stars. Through the analysis of stellar oscillation modes, it enables the precise characterisation of stellar interiors across a wide range of stellar masses and evolutionary phases, from the main sequence to the white dwarf phase. At the same time, the number of close stellar and planetary companions discovered throughout all stellar evolutionary phases has increased significantly, raising key questions about the interplay between stellar evolution and binarity.
Aims: In this study we investigated the competition between gravity waves excited by internal convection and those excited by tides in stars that host a companion. By modelling the energy and angular momentum luminosities transported by internal gravity waves stochastically excited by convection and by tides, we sought to quantify their relative contributions and identify the main parameters that govern their efficiency.
Methods: We computed the energy and angular momentum luminosities transported by both types of waves for a range of stellar masses and evolutionary stages, with a particular focus on understanding how the presence of a companion influences the angular momentum transport and the induced rotational evolution of the radiative layers of the host star.
Results: The competition between the two excitation mechanisms is sensitive to the mass and orbital properties of the companion, as well as the internal structure of the host star. We find that for a Jupiter-mass companion, the stochastic excitation dominates over tidal excitation during all evolutionary phases. Only for close-in stellar companions around late-type stars does the tidal excitation become more efficient.
Conclusions: The presence of a companion is unlikely to significantly alter the internal angular momentum transport in the radiative layers of the host star, simplifying the modelling of angular momentum transport driven by internal gravity waves in stars that host a companion.
Esseldeurs, M., Decin, L., De Ridder, J., Mori, Y., Karakas, A. I., Malfait, J., Danilovich Taı́ssa, Mathis, S., Richards, A. M. S., Sahai, R., Yates, J., Van de Sande, M., Baes, M., Baudry, A., Bolte, J., Ceulemans, T., De Ceuster, F., El Mellah, I., Etoka, S., … Wong, K. T. (2026). Evidence for the Keplerian orbit of a close companion around a giant star. Nature Astronomy, 10, 124–143.
@article{Esseldeurs2026,
author = {{Esseldeurs}, Mats and {Decin}, Leen and {De Ridder}, Joris and {Mori}, Yoshiya and {Karakas}, Amanda I. and {Malfait}, Jolien and {Danilovich}, Ta{\'\i}ssa and {Mathis}, St{\'e}phane and {Richards}, Anita M.~S. and {Sahai}, Raghvendra and {Yates}, Jeremy and {Van de Sande}, Marie and {Baes}, Maarten and {Baudry}, Alain and {Bolte}, Jan and {Ceulemans}, Thomas and {De Ceuster}, Frederik and {El Mellah}, Ileyk and {Etoka}, Sandra and {Gottlieb}, Carl and {Herpin}, Fabrice and {Kervella}, Pierre and {Landri}, Camille and {Marinho}, Louise and {McDonald}, Iain and {Menten}, Karl and {Millar}, Tom and {Osborn}, Zara and {Pimpanuwat}, Bannawit and {Plane}, John and {Price}, Daniel J. and {Siess}, Lionel and {Vermeulen}, Owen and {Wong}, Ka Tat},
title = {{Evidence for the Keplerian orbit of a close companion around a giant star}},
journal = {Nature Astronomy},
keywords = {Solar and Stellar Astrophysics},
year = {2026},
month = jan,
volume = {10},
pages = {124-143},
doi = {10.1038/s41550-025-02697-2},
archiveprefix = {arXiv},
eprint = {2511.11247},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2026NatAs..10..124E},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Close companions influence stellar evolution through tidal interactions, mass transfer, and mass loss effects. While such companions are detected around young stellar objects, main-sequence stars, red giants, and compact objects, direct observational evidence of close-in companions around asymptotic giant branch (AGB) stars has remained elusive. Here, we present (sub)millimeter time-domain imaging spectroscopy revealing the Keplerian motion of a close-in companion around the AGB star π1 Gruis. The companion, slightly more massive than the AGB star, is likely a main-sequence star. Unlike more evolved stars with companions at comparable distances, π 1 Gru’s companion follows a circular orbit, suggesting an eccentricity-generating mechanism late- or post-AGB. Our analysis suggests that model-predicted circularization rates may be underestimated. Our results highlight the potential of multi-epoch (sub)millimeter interferometry in detecting the Keplerian motion of close companions to giant stars and open avenues for our understanding of tidal interaction physics and binary evolution.
Esseldeurs, M., Mathis, S., & Decin, L. (2024). Tidal Dissipation in Evolved Low and Intermediate Mass Stars. Astronomy & Astrophysics, 690, A266.
@article{Esseldeurs2024,
author = {{Esseldeurs}, M. and {Mathis}, S. and {Decin}, L.},
title = {{Tidal Dissipation in Evolved Low and Intermediate Mass Stars}},
journal = {Astronomy & Astrophysics},
keywords = {methods: numerical, planet-star interactions, binaries: close, stars: evolution, planetary systems, Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics},
year = {2024},
month = oct,
volume = {690},
eid = {A266},
pages = {A266},
doi = {10.1051/0004-6361/202449648},
archiveprefix = {arXiv},
eprint = {2407.10573},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2024A&A...690A.266E},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Context. As the observed occurrence for planets or stellar companions orbiting low- and intermediate-mass evolved stars is increasing, so is the importance of understanding and evaluating the strength of their interactions. This is important for the further evolution of both our own Earth-Sun system and most of the observed exoplanetary systems. One of the most fundamental mechanisms behind this interaction is the tidal dissipation in these stars, as it is one of the engines of the orbital and rotational evolution of star-planet and star-star systems.
Aims. This article builds upon previous works that studied the evolution of the tidal dissipation along the pre-main sequence and the main sequence of low- and intermediate-mass stars and found a strong link between the structural and rotational evolution of stars and tidal dissipation. This article provides, for the first time, a complete picture of tidal dissipation along the entire evolution of low- and intermediate-mass stars, including the advanced phases of evolution.
Methods. Using stellar evolutionary models, the internal structure of the star was computed from the pre-main sequence all the way up to the white dwarf phase for stars with initial masses between 1 and 4 Msun. Using this internal structure, the tidal dissipation was computed along the entire stellar evolution. Tidal dissipation was separated into two components: the dissipation of the equilibrium (non-wave-like) tide and the dissipation of the dynamical (wave-like) tide. For evolved stars, the dynamical tide is constituted by progressive internal gravity waves. The evolution of the tidal dissipation was investigated for both the equilibrium and dynamical tides, and the results were compared.
Results. The significance of both the equilibrium and dynamical tide dissipation becomes apparent within distinct domains of the parameter space. The dissipation of the equilibrium tide is dominant when the star is large or the companion is far from the star. Conversely, the dissipation of the dynamical tide is important when the star is small or the companion is close to the star. The size and location of these domains depend on the masses of both the star and the companion, as well as on the evolutionary phase.
Conclusions. Both the equilibrium and the dynamical tides are important in evolved stars, and therefore both need to be taken into account when studying the tidal dissipation in evolved stars and the evolution of the planetary and/or stellar companions orbiting them.
Esseldeurs, M., Mathis, S., & Decin, L. (2024). Towards a complete picture of the evolution of planetary systems around evolved stars. In A. Lemaitre & A.-S. Libert (Eds.), IAU Symposium (Vol. 382, pp. 98–100).
@inproceedings{Esseldeurs2023b,
author = {{Esseldeurs}, Mats and {Mathis}, St{\'e}phane and {Decin}, Leen},
title = {{Towards a complete picture of the evolution of planetary systems around evolved stars}},
keywords = {AGB stars, stellar winds and mass-loss, tides, star-planet interactions},
booktitle = {IAU Symposium},
year = {2024},
editor = {{Lemaitre}, Anne and {Libert}, Anne-Sophie},
series = {IAU Symposium},
volume = {382},
month = jan,
pages = {98-100},
doi = {10.1017/S1743921323004817},
adsurl = {https://ui.adsabs.harvard.edu/abs/2024IAUS..382...98E},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Solar-like stars evolve through the Asymptotic Giant Branch (AGB) phase. This phase is characterized by increased radii, high luminosities, and significant mass loss. In order to understand the survival of companions during this phase, and explain the presence of planets orbiting white dwarfs, it is essential to examine the orbital evolution of these systems. Several physical mechanisms come into play for AGB stars, such as stellar mass-loss and tidal interactions between the star and its companion. On the one hand, evaluating mass-loss rates and accretion to the companion requires complex radiation-hydro-chemical simulations. On the other hand, the full history of tidal dissipation in low-mass stars during their late stages of evolution, which strongly depends on internal structure and boundary conditions, still requires dedicated studies. Finally a simultaneous treatment of winds and tides is required to predict a planet’s orbital evolution.
Esseldeurs, M., Siess, L., De Ceuster, F., Homan, W., Malfait, J., Maes, S., Konings, T., Ceulemans, T., & Decin, L. (2023). 3D simulations of AGB stellar winds. II. Ray-tracer implementation and impact of radiation on the outflow morphology. Astronomy & Astrophysics, 674, A122.
@article{Esseldeurs2023a,
author = {{Esseldeurs}, M. and {Siess}, L. and {De Ceuster}, F. and {Homan}, W. and {Malfait}, J. and {Maes}, S. and {Konings}, T. and {Ceulemans}, T. and {Decin}, L.},
title = {{3D simulations of AGB stellar winds. II. Ray-tracer implementation and impact of radiation on the outflow morphology}},
journal = {Astronomy & Astrophysics},
keywords = {stars: winds, outflows, methods: numerical, hydrodynamics, stars: AGB and post-AGB, radiative transfer, Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies},
year = {2023},
month = jun,
volume = {674},
eid = {A122},
pages = {A122},
doi = {10.1051/0004-6361/202346282},
archiveprefix = {arXiv},
eprint = {2304.09786},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2023A&A...674A.122E},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Context. Stars with an initial mass below ∼ 8 M⊙ will evolve through the Asymptotic Giant Branch (AGB) phase, during which they develop a strong stellar wind, due to radiation pressure on newly formed dust grains. Recent observations have revealed significant morphological complexities in AGB outflows, which are most probably caused by the interaction with a companion.
Aims. We aim for a more accurate description of AGB wind morphologies by accounting for both the radiation force in dust-driven winds and the impact of a companion on the AGB wind morphology.
Methods. We present the implementation of a ray-tracer for radiative transfer in the smoothed particle hydrodynamics (SPH) code Phantom. Our method allows for the creation of a 3D map of the optical depth around the AGB star. The effects of 4 different descriptions of radiative transfer, with different degrees of complexity, are compared: the free-wind approximation, the geometrical approximation, the Lucy approximation, and the attenuation approximation. Finally, we compare the Lucy and attenuation approximation to predictions with the 3D radiative transfer code Magritte.
Results. The effects of the different radiative transfer treatments are analysed considering both a low and high mass-loss rate regime and this both in the case of a single AGB star, as well as for an AGB binary system. For both low and high mass-loss rates, the velocity profile of the outflow is modified when going from the free-wind to the geometrical approximation, also resulting in a different wind morphology for AGB binary systems. In the case of a low mass-loss rate, the effect of the Lucy and attenuation approximation is negligible due to the low densities but morphological differences appear in the high mass-loss rate regime. By comparing the radiative equilibrium temperature and radiation force to the predictions from Magritte, we show that for most of the model the Lucy approximation works best, although close to the companion artificial heating occurs; and that it fails to simulate the shadow cast by the companion. The attenuation approximation leads to a stronger absorption of the radiation field yielding lower equilibrium temperature, weaker radiation force but produces the shadow cast by the companion. From the predictions of the 3D radiative transfer code Magritte, we also conclude that a radially directed radiation force is a reasonable assumption.
Conclusions. The radiation force plays a critical role in dust-driven AGB winds, impacting the velocity profile and morphological structures. For low mass-loss rates, the geometrical approximation suffices, but for high mass-loss rates a more rigorous method is required. Among the studied approaches, the Lucy approximation provides the most accurate results, although it does not account for all effects.
Thesis
Esseldeurs, M. (2026). The orbital evolution of AGB binary systems. KU Leuven. Faculteit Wetenschappen. PhD thesis.
@thesis{Esseldeurs2022d,
language = {eng},
publisher = {KU Leuven. Faculteit Wetenschappen. PhD thesis},
title = {The orbital evolution of AGB binary systems},
year = {2026},
author = {Esseldeurs, Mats},
address = {Leuven}
}
Binary and multiple stellar systems hosting evolved stars provide unique laboratories for studying the coupled evolution of stellar structure, mass loss, tidal interactions, and orbital dynamics. During the Asymptotic Giant Branch (AGB) phase, stars undergo intense pulsation-enhanced, dust-driven winds that expel a substantial fraction of their envelope. This mass loss not only governs the late evolution of the star itself, but also reshapes the orbital configuration of surrounding companions and sculpts the circumstellar environment into spirals, disks, and bipolar outflows. At the same time, tidal interactions act to dissipate energy and transfer angular momentum, often counteracting wind-driven orbital expansion. Predicting the fate of such systems therefore requires a unified treatment of waves, winds, and tides across a wide range of spatial and temporal scales. Prior to this work, the interplay between these processes has been modelled using prescriptions that lacked physical ab-initio modelling and used simplified prescriptions that often neglect key physical ingredients. In this thesis, I investigate the competition and interplay between mass-loss processes and tidal dissipation in evolved binary systems through a multi-method approach that combines analytical theory, stellar evolution modelling, and three-dimensional hydrodynamical simulations.
In order to couple the full physics of the pulsation enhanced dust-driven winds with the orbital dynamics, I first developed a new ray-tracing scheme to compute the radiative acceleration on dust grains in the outflow. This method accounts for the complex geometry of the circumstellar environment and the anisotropic radiation field, enabling self-consistent calculations of wind acceleration in binary systems.
Furthermore, I performed stellar evolution calculations to characterize the internal structure and convective properties of evolved stars. Using these models, I carried out a full parameter study of tidal dissipation in both the convective and radiative regions of stars, throughout their entire evolution, to determine the efficiency of the different tidal mechanisms, namely the equilibrium tide and tidally-excited progressive internal gravity waves, as a function of stellar mass, age, and the orbital configuration of the system.
I integrated these components into an orbital evolution framework that tracks the evolution of both the semi-major axis and eccentricity of binaries hosting evolved stars. This framework incorporates the effects of tidal dissipation and mass loss, allowing for predictions of the long-term orbital evolution. I applied this framework to a range of observed systems, to the newly confirmed close binary system of π1 Gru, as well as to the future evolution of our Earth-Sun system.
The combined framework developed in this thesis therefore provides a coherent picture of how mass loss, tides, and convection jointly determine the orbital evolution and observable signatures of evolved binaries. The results place new constraints on tidal prescriptions used in binary population synthesis, refine predictions for common-envelope progenitors, and aid the interpretation of resolved circumstellar structures. More broadly, this work advances our understanding of how binary interaction channels shape the late stages of stellar evolution and the diversity of their astrophysical outcomes, including those of planetary systems.
Esseldeurs, M. (2022). SPH Approach to Modelling Dust Attenuation of the Wind Acceleration in AGB Binaries. KU Leuven. Faculteit Wetenschappen. Master thesis.
@thesis{Esseldeurs2022,
language = {eng},
publisher = {KU Leuven. Faculteit Wetenschappen. Master thesis},
title = {SPH Approach to Modelling Dust Attenuation of the Wind Acceleration in AGB Binaries},
year = {2022},
author = {Esseldeurs, Mats},
address = {Leuven}
}
Circumstellar envelopes of asymptotic giant branch (AGB) stars have for a long time been modelled assuming a spherical symmetry. However, recent observations of the inner winds of these stars have shown that they exhibit a variety of complex structures, such as spirals, equatorial density enhancements, disks, bipolar outflows, etc. These structures are believed to originate from the presence of a companion, either stellar and/or planetary. Due to the inherently three-dimensional (3D) nature of this phenomenon, its investigation requires advanced 3D-simulations. It has already been shown that using hydrodynamic simulations, some of these wind morphologies can be obtained. However, the computational cost of truly selfconsistent calculations, including the crucial chemical and radiation processes, is currently still computationally prohibitive. Therefore, incremental modelling improvements using ever more refined approximations can significantly advance the quality and physical consistency of the simulations. One such problem revolves around the transfer of momentum from the stellar photons to the dust particles in the AGB wind. Until recently, this coupling has always either been ignored, or treated in the optically thin limit, which only requires knowledge on the local quantities. However, properly accounting for the dust opacity and its attenuation of the stellar radiation field can drastically affect the effective radiation pressure on the dust. In turn, this can significantly alter the dynamics and morphology of these stellar winds.
In the context of a large collaboration that revolves around upgrading the treatment of dusty winds within the smoothed-particle-hydrodynamics code PHANTOM, I have worked on levelling up the way in which dust acceleration is calculated. To calculate the attenuation of the stellar radiation field, knowledge on the distribution and optical properties of the matter in-between each particle and the star is required. To this end the ray-tracing algorithm of the radiative transfer code MAGRITTE was extracted, made compatible with the SPH philosophy, and coupled to PHANTOM. We investigated different options to speed up the ray-tracer with only a minimal loss in accuracy. We show that the best results are found when rays are traced outwards from the star in a uniform distribution, set by HEALPix. Because not all particles are struck by a ray, we also investigated different interpolation approaches. We find that interpolation scaling with the inverse square of the perpendicular distance to the four closest rays gives the most desirable result. Finally, we demonstrate the validity of our new approach in a simulation.
Co-author publications
Figueira, P., Fontanet, E., Faria, J. P., Esseldeurs, M., Friden, E., Leleu, A., Luque, R., Ottoni, G., Ségransan, D., Stalport, M., Tavella, S., & Udry, S. (2026). CORALIE radial-velocity search for companions around evolved stars (CASCADES) V. Three planetary companions and achievable precision. ArXiv e-Prints, arXiv:2606.09072.
@article{Figueira2026,
author = {{Figueira}, P. and {Fontanet}, E. and {Faria}, J.~P. and {Esseldeurs}, M. and {Friden}, E. and {Leleu}, A. and {Luque}, R. and {Ottoni}, G. and {S{\'e}gransan}, D. and {Stalport}, M. and {Tavella}, S. and {Udry}, S.},
title = {{CORALIE radial-velocity search for companions around evolved stars (CASCADES) V. Three planetary companions and achievable precision}},
journal = {arXiv e-prints},
keywords = {Earth and Planetary Astrophysics, Solar and Stellar Astrophysics},
year = {2026},
month = jun,
eid = {arXiv:2606.09072},
pages = {arXiv:2606.09072},
doi = {10.48550/arXiv.2606.09072},
archiveprefix = {arXiv},
eprint = {2606.09072},
primaryclass = {astro-ph.EP},
adsurl = {https://ui.adsabs.harvard.edu/abs/2026arXiv260609072F},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Aims: We expand the planetary census around massive stellar hosts through a long-term campaign of high-precision radial velocity (RV) measurements on evolved stars.
Methods: We analyse data acquired with the CORALIE spectrograph covering 15-18 years on HD125136, HD127195, and HD220218. Stellar parameters are derived through different methods for a comprehensive characterization of each star. We then evaluate the presence of planetary signals in the RV time series using the Bayesian inference tool kima. Finally, we design an observing strategy aimed at mitigating the impact of pulsations on evolved stars and test its effectiveness on the low-luminosity red giant HD127195.
Results: We detect signals that are accurately modelled by Keplerian curves in the RV data of the three stars: one on HD 125136, two on HD 127195, and one on HD 220218. While the signals on the first two stars seem to be of planetary origin, the signal on the third one shows several signs of stellar activity. We therefore identify a planetary companion around HD125136 with a minimum mass of 2.26 MJup on an 850 d orbit, and on HD127195 we identify a system composed of planets with 0.66 MJup and 0.78 MJup with orbital periods of 535 d and 834 d, respectively.
Conclusions: We detect three massive planets around two low-luminosity red giant stars in a region of the parameter space that is poorly populated in both stellar mass and planetary orbital periods. The dedicated observing campaign on HD127195 showcases how stellar pulsations can be efficiently averaged out to below 5 m/s in low-luminosity giant stars.
Danilovich, T., Samaratunge, N., Mori, Y. L., Richards, A. M. S., Baudry, A., Etoka, S., Montargès, M., Kervella, P., McDonald, I., Gottlieb, C. A., Wallace, A., Price, D. J., Decin, L., Bolte, J., Ceulemans, T., De Ceuster, F., de Koter, A., Dionese, D., El Mellah, I., … Zijlstra, A. (2025). ATOMIUM: Continuum emission and evidence of dust enhancement from binary motion. Astronomy & Astrophysics, 704, A341.
@article{Danilovich2025,
author = {{Danilovich}, T. and {Samaratunge}, N. and {Mori}, Y.~L. and {Richards}, A.~M.~S. and {Baudry}, A. and {Etoka}, S. and {Montarg{\`e}s}, M. and {Kervella}, P. and {McDonald}, I. and {Gottlieb}, C.~A. and {Wallace}, A. and {Price}, D.~J. and {Decin}, L. and {Bolte}, J. and {Ceulemans}, T. and {De Ceuster}, F. and {de Koter}, A. and {Dionese}, D. and {El Mellah}, I. and {Esseldeurs}, M. and {Gray}, M. and {Herpin}, F. and {Khouri}, T. and {Lagadec}, E. and {Landri}, C. and {Marinho}, L. and {Menten}, K.~M. and {Millar}, T.~J. and {M{\"u}ller}, H.~S.~P. and {Pimpanuwat}, B. and {Plane}, J.~M.~C. and {Sahai}, R. and {Siess}, L. and {Van de Sande}, M. and {Vermeulen}, O. and {Wong}, K.~T. and {Yates}, J. and {Zijlstra}, A.},
title = {{ATOMIUM: Continuum emission and evidence of dust enhancement from binary motion}},
journal = {Astronomy & Astrophysics},
keywords = {stars: AGB and post-AGB, circumstellar matter, submillimeter: stars, Solar and Stellar Astrophysics, Astrophysics of Galaxies},
year = {2025},
month = dec,
volume = {704},
eid = {A341},
pages = {A341},
doi = {10.1051/0004-6361/202554878},
archiveprefix = {arXiv},
eprint = {2504.00517},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2025A&A...704A.341D},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
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. Here we present ALMA observations of the continuum emission at 1.24 mm around a sample of 17 stars from the ATOMIUM survey. 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 stellar radius and period only for the Mira variables with periods above 300 days and a positive trend between the period and the monochromatic luminosity only for the red supergiants and the most extreme AGB stars with periods above 500 days. We find that the continuum emission at 1.24 mm can be classified into four groups. "Featureless" continuum emission is confined to the (unresolved) regions close to the star for five stars in our sample, relatively uniform extended flux is seen for four stars, tentative bipolar features are seen for three stars, and the remaining five stars have unique or unusual morphological features in their continuum maps. These features can be explained by binary companions to 10 out of the 14 AGB stars in our sample. 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 mass lost through the dust driven wind. This explains the different dust morphologies seen around our stars and partly accounts for a large scatter in literature mass-loss rates, especially among semiregular stars with small pulsation periods.
Decin, L., Vermeulen, O., Esseldeurs, M., Driessen, F. A., Landri, C., Dionese, D., Siess, L., & Skowron, D. M. (2025). Eppur si eclissa: Eccentric low-mass companions and time-in-dust selection to explain long secondary periods. Astronomy & Astrophysics, 703, L23.
@article{Decin2025,
author = {{Decin}, L. and {Vermeulen}, O. and {Esseldeurs}, M. and {Driessen}, F.~A. and {Landri}, C. and {Dionese}, D. and {Siess}, L. and {Skowron}, D.~M.},
title = {{Eppur si eclissa: Eccentric low-mass companions and time-in-dust selection to explain long secondary periods}},
journal = {Astronomy & Astrophysics},
keywords = {stars: AGB and post-AGB, binaries: eclipsing, binaries: general, circumstellar matter, stars: mass-loss, stars: variables: general, Solar and Stellar Astrophysics},
year = {2025},
month = nov,
volume = {703},
eid = {L23},
pages = {L23},
doi = {10.1051/0004-6361/202557634},
archiveprefix = {arXiv},
eprint = {2510.24281},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2025A&A...703L..23D},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Context. Long Secondary Periods (LSPs) are observed in ∼1/3 of pulsating red giants yet remain unexplained. Four key observational constraints anchor the discussion: (i) a ∼30% occurrence rate in semi-regular variable AGB stars (SRVs) with a much lower rate (or absence) in regularly pulsating Mira-type AGB stars (Miras), (ii) ∼50% of LSP stars show a secondary mid-IR minimum; (iii) Keplerian fits to radial-velocity (RV) curves favour the argument of periastron ω > 180°; and (iv) the RV-light curve phase lag clusters around −π/2.
Aims. We test whether a close-in, eccentric low-mass companion that only spends part of its orbit within the giant’s dust-formation (wind-launching) zone can match all four empirical facts.
Methods. Guided by observed RV amplitudes and periods of ∼500 - 1500 days, we adopt a companion’s mass M2 ∈ [0.08, 0.25] M⊙, orbital separation a ∈ [1.5, 3] au, eccentricty e ≤ 0.6, and take the dust condensation radius Rcond ∼ 2.5–3 au for SRVs (larger for Miras via scaling with luminosity). We compute the time-in-dust fraction fdust (time with r≥Rcond) and apply line-of-sight criteria: an LSP requires orbital inclination i ≥ iLSP and fdust ≥ fmin; a secondary mid-IR minimum interpreted as secondary eclipse further needs i ≥ iecl > iLSP and superior conjunction. We test the first three empirical facts analytically, then model the RV-light phase offset with 3D hydrodynamical simulations.
Results. Our proposed scenario explains the observed excess of ω >180°. For SRV-like parameters we obtain an LSP detectability of ∼31.6 ± 0.1%, while Mira-type conditions yield ∼3.0 ± 0.1%; for both scenarios the conditional secondary mid-IR eclipse fraction is ∼44%. Our hydrodynamical models place the optical-depth peak just downstream of the companion near apastron, then shift it to ∼90-225° phase offsets later in the orbit - consistent with the RV-light offsets.
Conclusions. A time-in-dust geometric selection for low-mass companions in close eccentric orbits explains the four key empirical facts constraining the LSP mechanism.
Willcox, R., Marchant, P., Vigna-Gómez, A., Sana, H., Bodensteiner, J., Deshmukh, K., Esseldeurs, M., Fabry, M., Hénault-Brunet, V., Janssens, S., Mahy, L., Patrick, L., Pauli, D., Renzo, M., Sander, A. A. C., Shenar, T., van Son, L. A. C., & Stoop, M. (2025). Binarity at LOw Metallicity (BLOeM): Bayesian inference of natal kicks from inert black hole binaries. Astronomy & Astrophysics, 700, A59.
@article{Willcox2025,
author = {{Willcox}, R. and {Marchant}, P. and {Vigna-G{\'o}mez}, A. and {Sana}, H. and {Bodensteiner}, J. and {Deshmukh}, K. and {Esseldeurs}, M. and {Fabry}, M. and {H{\'e}nault-Brunet}, V. and {Janssens}, S. and {Mahy}, L. and {Patrick}, L. and {Pauli}, D. and {Renzo}, M. and {Sander}, A.~A.~C. and {Shenar}, T. and {van Son}, L.~A.~C. and {Stoop}, M.},
title = {{Binarity at LOw Metallicity (BLOeM): Bayesian inference of natal kicks from inert black hole binaries}},
journal = {Astronomy & Astrophysics},
keywords = {methods: data analysis, binaries: general, stars: black holes, stars: massive, Solar and Stellar Astrophysics, Astrophysics of Galaxies, High Energy Astrophysical Phenomena},
year = {2025},
month = aug,
volume = {700},
eid = {A59},
pages = {A59},
doi = {10.1051/0004-6361/202555274},
archiveprefix = {arXiv},
eprint = {2504.16669},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2025A&A...700A..59W},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Context. The emerging population of inert black hole binaries (BHBs) provides a unique opportunity to constrain black hole (BH) formation physics. These systems are composed of a stellar-mass BH in a wide orbit around a non-degenerate star with no observed Xray emission. Inert BHBs allow for narrow constraints to be inferred on the natal kick and mass loss during BH-forming core-collapse events.
Aims. In anticipation of the upcoming BLOeM survey, we aim to provide tight constraints on BH natal kicks by exploiting the full parameter space obtained from combined spectroscopic and astrometric data to characterize the orbits of inert BHBs. Multi-epoch spectroscopy from the BLOeM project will provide measurements of periods, eccentricities, and radial velocities for inert BHBs in the SMC, which complements Gaia astrometric observations of proper motions.
Methods. We present a Bayesian parameter estimation framework to infer natal kicks and mass loss during core-collapse from inert BHBs, accounting for all available observables, including the systemic velocity and its orientation relative to the orbital plane. The framework further allows for circumstances when some of the observables are unavailable, such as for the distant BLOeM sources which preclude resolved orbits.
Results. With our new framework, we are able to distinguish between BH formation channels, even in the absence of a resolved orbit. In cases when the pre-explosion orbit can be assumed to be circular, we precisely recover the parameters of the core-collapse, highlighting the importance of understanding the eccentricity landscape of pre-explosion binaries, both theoretically and observationally. Treating the near-circular, inert BHB, VFTS 243, as a representative of the anticipated BLOeM systems, we constrain the natal kick to less than 27 km/s and the mass loss to less than 2.9 Msun within a 90% credible interval.
Vermeulen, O., Esseldeurs, M., Malfait, J., Ceulemans, T., Siess, L., Matsumoto, K., De Ceuster, F., Danilovich, T., Landri, C., & Decin, L. (2025). Impact of a binary companion in AGB outflows on CO spectral lines. Astronomy & Astrophysics, 700, A85.
@article{Vermeulen2025,
author = {{Vermeulen}, O. and {Esseldeurs}, M. and {Malfait}, J. and {Ceulemans}, T. and {Siess}, L. and {Matsumoto}, K. and {De Ceuster}, F. and {Danilovich}, T. and {Landri}, C. and {Decin}, L.},
title = {{Impact of a binary companion in AGB outflows on CO spectral lines}},
journal = {Astronomy & Astrophysics},
keywords = {hydrodynamics, radiative transfer, methods: numerical, stars: AGB and post-AGB, stars: winds, outflows, Solar and Stellar Astrophysics},
year = {2025},
month = aug,
volume = {700},
eid = {A85},
pages = {A85},
doi = {10.1051/0004-6361/202554905},
archiveprefix = {arXiv},
eprint = {2507.03583},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2025A&A...700A..85V},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Context. In the late stage of their evolution, low- to intermediate-mass stars pass through the asymptotic giant branch (AGB) phase. AGB stars are characterised by strong mass loss through dust driven winds. High angular resolution interferometric observations reveal that these winds harbour strong deviations from spherical symmetry, such as spirals and arcs, believed to be caused by hidden (sub-)stellar companions. Such observations are scarce, and much more often observed features from these systems are molecular spectral lines, where the presence of a companion is less clear.
Aims. Our aim is to study the impact of a binary companion on low-J CO spectral lines of AGB star outflows. By varying the orbital separation and wind velocity, we aim to find line shapes characteristic of more complex binary-induced morphologies. This would allow us to quantify whether a companion can be identified from spectral lines, or if it remains hidden in the line profiles.
Methods. We generated a new grid of nine 3D models of a mass-losing AGB star using the smoothed particle hydrodynamics (SPH) code PHANTOM, with three values for both the outflow velocity and orbital separation. We created a novel method for calculating the CO photodissociation in asymmetric outflows in order to determine the size of the emitting envelope. Utilising the 3D non-local thermodynamic equilibrium (NLTE) radiative transfer code MAGRITTE, we created synthetic spectral lines for the low rotational transitions of CO at different inclinations and position angles.
Results. Our hydrodynamical simulations show a variety of morphologies, always with a pronounced spiral structure arising in the orbital plane, but with varying shapes in the meridional plane, and different degrees of global flattening. CO photodissociation closely follows the global morphology, thereby creating a non-spherical emitting region. We find that the low-J CO line profiles can deviate strongly from the parabolic or flat-topped profiles expected from non-resolved spherically symmetric outflows. A variety of line shapes emerge, with two peaks near the terminal velocity, and a central bump near the central velocity being the most pronounced. The line shapes strongly depend on the underlying morphology and inclination. In specific cases the spectral lines can appear parabolic, hiding the presence of a binary companion.
Conclusions. We find that a binary companion can have a pronounced impact on the resulting CO spectral lines, and thus the molecular line profiles can serve as a binary diagnostic. However, the influence of the companion on the line can also go easily unnoticed as the characteristic features can be concealed by the beam profile and the noise of the observations. Therefore, it is easy to misclassify systems as single stars. Neglecting the impact of a binary companion when modelling the CO spectral lines can thus cause systematic errors on the derived mass-loss rates.
Montargès, M., Malfait, J., Esseldeurs, M., de Koter, A., Baron, F., Kervella, P., Danilovich, T., Richards, A. M. S., Sahai, R., McDonald, I., Khouri, T., Shetye, S., Zijlstra, A., Van de Sande, M., El Mellah, I., Herpin, F., Siess, L., Etoka, S., Gobrecht, D., … Yates, J. (2025). An accreting dwarf star orbiting the S-type giant star pi1 Gru. Astronomy & Astrophysics, 699, A22.
@article{Montarges2025,
author = {{Montarg{\`e}s}, M. and {Malfait}, J. and {Esseldeurs}, M. and {de Koter}, A. and {Baron}, F. and {Kervella}, P. and {Danilovich}, T. and {Richards}, A.~M.~S. and {Sahai}, R. and {McDonald}, I. and {Khouri}, T. and {Shetye}, S. and {Zijlstra}, A. and {Van de Sande}, M. and {El Mellah}, I. and {Herpin}, F. and {Siess}, L. and {Etoka}, S. and {Gobrecht}, D. and {Marinho}, L. and {Wallstr{\"o}m}, S.~H.~J. and {Wong}, K.~T. and {Yates}, J.},
title = {{An accreting dwarf star orbiting the S-type giant star pi1 Gru}},
journal = {Astronomy & Astrophysics},
keywords = {stars: AGB and post-AGB, binaries: close, circumstellar matter, stars: imaging, stars: mass-loss, stars: individual: pi1 Gru, Solar and Stellar Astrophysics},
year = {2025},
month = jul,
volume = {699},
eid = {A22},
pages = {A22},
doi = {10.1051/0004-6361/202452587},
archiveprefix = {arXiv},
eprint = {2504.16845},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2025A&A...699A..22M},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Aims. We aim to characterize the properties of the inner companion of the S-type AGB star pi1 Gru, and to identify plausible future evolution scenarios for this triple system.
Methods. We observed pi1 Gru with ALMA and VLT/SPHERE. In addition, we collected archival photometry data and used the Hipparcos-Gaia proper motion anomaly. We derive the best orbital parameters from Bayesian inference.
Results. The inner companion, pi1 Gru C was located at 37.4 +/- 2.0 mas from the primary in June-July 2019 (projected separation of 6.05 +/- 0.55 au at 161.7 +/- 11.7 pc). The best orbital solution gives a companion mass of 0.86 (+0.22/-0.20) Msun (using the derived mass of the primary), and a semi-major axis of 7.05 (+0.54/-0.57) au. This leads to an orbital period of 11.0 (+1.7/-1.5) yr. The best solution is an elliptical orbit with eccentricity e = 0.35 (+0.18/-0.17), but a circular orbit cannot be totally excluded. The close companion can either be a K1V (F9.5V/K7V) star or a white dwarf. The ultraviolet and millimeter continuum photometry are consistent with the presence of an accretion disk around the close companion. The ultraviolet emission could then either originate in hot spots in an overall cooler disk, or also from a hot disk in case the companion is a white dwarf.
Conclusions. Though the close companion and the AGB star are interacting, and an accretion disk is observed around the companion, the mass-accretion rate is too low to cause a Ia supernova but could produce novae every 900 yr. Short wavelength spatially resolved observations are needed to further constrain the nature of the C companion. Searches for close-in companions similar to this system will help to better understand the physics of mass- and angular-momentum transfer, and orbital evolution in the late evolutionary stages.
Malfait, J., Siess, L., Esseldeurs, M., De Ceuster, F., Wallström, S. H. J., de Koter, A., & Decin, L. (2024). Impact of H I cooling and study of accretion disks in asymptotic giant branch wind-companion smoothed particle hydrodynamic simulations. Astronomy & Astrophysics, 691, A84.
@article{Malfait2024a,
author = {{Malfait}, J. and {Siess}, L. and {Esseldeurs}, M. and {De Ceuster}, F. and {Wallstr{\"o}m}, S.~H.~J. and {de Koter}, A. and {Decin}, L.},
title = {{Impact of H I cooling and study of accretion disks in asymptotic giant branch wind-companion smoothed particle hydrodynamic simulations}},
journal = {Astronomy & Astrophysics},
keywords = {methods: numerical, stars: AGB and post-AGB, binaries: general, stars: winds, outflows, Astrophysics - Solar and Stellar Astrophysics},
year = {2024},
month = nov,
volume = {691},
eid = {A84},
pages = {A84},
doi = {10.1051/0004-6361/202450338},
archiveprefix = {arXiv},
eprint = {2408.13158},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2024A&A...691A..84M},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Context. High-resolution observations reveal that the outflows of evolved low- and intermediate-mass stars harbour complex morphological structures that are linked to the presence of one or multiple companions. Hydrodynamical simulations provide a way to study the impact of a companion on the shaping of the asymptotic giant branch (AGB) star out-flow.
Aims. Using smoothed particle hydrodynamic (SPH) simulations of an AGB star undergoing mass loss, which also has a binary companion, we study the impact of including H I atomic line cooling on the flow morphology. We also study how this affects the properties of the accretion disks that form around the companion.
Methods. We used the PHANTOM code to perform high-resolution 3D SPH simulations of the interaction of a solar-mass companion with the outflow of an AGB star, using different wind velocities and eccentricities. We compared the model properties, computed with and without the inclusion of H I cooling.
Results. The inclusion of H I cooling produces a sizeable decrease in the temperature, up to one order of magnitude, in the region closely surrounding the companion star. As a consequence, the morphological irregularities and relatively energetic (bipolar) outflows that were obtained without H I cooling no longer appear. In the case of an eccentric orbit and a low wind velocity, these morphologies are still highly asymmetric, but the same structures recur at every orbital period, making the morphology more regular. Flared accretion disks, with a (sub-)Keplerian velocity profile, are found to form around the companion in all our models with H I cooling, provided the accretion radius is small enough. The disks have radial sizes ranging from about 0.4 to 0.9 au and masses around 10‑7‑10‑8 M⊙. For the considered wind velocities, mass accretion onto the companion is up to a factor of 2 higher than predicted by the standard Bondi Hoyle Littleton rate, ranging between 4 to 21% of the AGB wind mass loss rate. The lower the wind velocity at the location of the companion, the larger and the more massive the disk and the higher the mass accretion efficiency. In eccentric systems, the disk size, disk mass, and mass accretion efficiency vary, depending on the orbital phase.
Conclusions. H I cooling is an essential ingredient to properly model the medium around the companion where density-enhanced wind structures form and it favours the formation of an accretion disk.
Malfait, J., Siess, L., Vermeulen, O., Esseldeurs, M., Wallström, S. H. J., Richards, A. M. S., De Ceuster, F., Maes, S., Bolte, J., & Decin, L. (2024). SPH modelling of AGB wind morphology in hierarchical triple systems and a comparison to observation of R Aql. Astronomy & Astrophysics, 691, A57.
@article{Malfait2024b,
author = {{Malfait}, J. and {Siess}, L. and {Vermeulen}, O. and {Esseldeurs}, M. and {Wallstr{\"o}m}, S.~H.~J. and {Richards}, A.~M.~S. and {De Ceuster}, F. and {Maes}, S. and {Bolte}, J. and {Decin}, L.},
title = {{SPH modelling of AGB wind morphology in hierarchical triple systems and a comparison to observation of R Aql}},
journal = {Astronomy & Astrophysics},
keywords = {hydrodynamics, methods: numerical, stars: AGB and post-AGB, binaries: close, stars: winds, outflows, ISM: jets and outflows, Astrophysics - Solar and Stellar Astrophysics},
year = {2024},
month = nov,
volume = {691},
eid = {A57},
pages = {A57},
doi = {10.1051/0004-6361/202450844},
archiveprefix = {arXiv},
eprint = {2408.16565},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2024A&A...691A..57M},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Context. Complex asymmetric 3D structures are observed in the outflows of evolved low- and intermediate-mass stars, and are believed to be shaped through the interaction of companions that remain hidden within the dense wind. One example is the AGB star R Aql, for which ALMA (Atacama Large Millimeter Array) observations have revealed complex wind structures that might originate from a higher-order stellar system.
Aims. We investigate how triple systems can shape the outflow of asymptotic giant branch (AGB) stars and characterise the different wind structures that form. For simplicity, we solely focus on co-planar systems in a hierarchical, stable orbit, consisting of an AGB star with one relatively close companion, and another one at a large orbital separation.
Methods. We modelled a grid of hierarchical triple systems including a wind-launching AGB star, with the smoothed-particle- hydrodynamic PHANTOM code. We varied the outer companion mass, the AGB wind velocity, and the orbital eccentricities to study the impact of these parameters on the wind morphology. To study the impact of adding a triple companion, we additionally modelled and analysed a small grid of binary sub-systems, for comparison. To investigate if R Aql could be shaped by a triple system, we postprocessed one of our triple models with a radiative transfer routine, and compared this to data of the ALMA ATOMIUM programme.
Results. The characteristic wind structures resulting from a hierarchical triple system are the following. A large two-edged spiral wake results behind the outer companion star. This structure lies on top of the spiral structure formed by the close binary, which is itself affected by the orbital motion around the system’s centre of mass, such that it resembles a snail-shell pattern. This dense inner spiral pattern interacts with, and strongly impacts, the spiral wake of the outer companion, resulting in a wave pattern on the outer edge of this spiral wake. The higher the mass of the outer companion, the larger the density enhancement and the more radially compressed the outer spiral. Lowering the wind velocity has a similar effect, and additionally results in an elongation of the global wind morphology. Introducing eccentricity in the inner and outer orbit of the hierarchical system results in complex phase-dependent wind-companion interactions, and consequently in asymmetries in the inner part of the wind and the global morphology, respectively. From the comparison of our models to the observations of R Aql, we conclude that this circumstellar environment might be shaped by a similar system to the ones modelled in this work, but an elaborate study of the observational data is needed to better determine the orbital parameters and characteristics of the central system.
Conclusions. The modelled outflow of an AGB star in a co-planar hierarchical systems is characterised by a large-scale spiral wake with a wavey outer edge, attached to the outer companion, on top of a compact inner spiral pattern that resembles a snail-shell pattern.
Wallström, S. H. J., Danilovich, T., Müller, H. S. P., Gottlieb, C. A., Maes, S., Van de Sande, M., Decin, L., Richards, A. M. S., Baudry, A., Bolte, J., Ceulemans, T., De Ceuster, F., de Koter, A., El Mellah, I., Esseldeurs, M., Etoka, S., Gobrecht, D., Gottlieb, E., Gray, M., … Zijlstra, A. (2024). ATOMIUM: Molecular inventory of 17 oxygen-rich evolved stars observed with ALMA. Astronomy & Astrophysics, 681, A50.
@article{Wallstrom2024,
author = {{Wallstr{\"o}m}, S.~H.~J. and {Danilovich}, T. and {M{\"u}ller}, H.~S.~P. and {Gottlieb}, C.~A. and {Maes}, S. and {Van de Sande}, M. and {Decin}, L. and {Richards}, A.~M.~S. and {Baudry}, A. and {Bolte}, J. and {Ceulemans}, T. and {De Ceuster}, F. and {de Koter}, A. and {El Mellah}, I. and {Esseldeurs}, M. and {Etoka}, S. and {Gobrecht}, D. and {Gottlieb}, E. and {Gray}, M. and {Herpin}, F. and {Jeste}, M. and {Kee}, D. and {Kervella}, P. and {Khouri}, T. and {Lagadec}, E. and {Malfait}, J. and {Marinho}, L. and {McDonald}, I. and {Menten}, K.~M. and {Millar}, T.~J. and {Montarg{\`e}s}, M. and {Nuth}, J.~A. and {Plane}, J.~M.~C. and {Sahai}, R. and {Waters}, L.~B.~F.~M. and {Wong}, K.~T. and {Yates}, J. and {Zijlstra}, A.},
title = {{ATOMIUM: Molecular inventory of 17 oxygen-rich evolved stars observed with ALMA}},
journal = {Astronomy & Astrophysics},
keywords = {stars: AGB and post-AGB, supergiants, circumstellar matter, line: identification, instrumentation: interferometers, astrochemistry, Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies},
year = {2024},
month = jan,
volume = {681},
eid = {A50},
pages = {A50},
doi = {10.1051/0004-6361/202347632},
archiveprefix = {arXiv},
eprint = {2312.03467},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2024A&A...681A..50W},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
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.</pre>
</div>
</li>
Maes, S., Siess, L., Homan, W., Malfait, J., De Ceuster, F., Ceulemans, T., Donné, D., Esseldeurs, M., & Decin, L. (2022). Route towards complete 3D hydro-chemical simulations of companion-perturbed AGB outflows. The Origin of Outflows in Evolved Stars, 366, 227–233.
@inproceedings{Maes2022,
author = {{Maes}, Silke and {Siess}, Lionel and {Homan}, Ward and {Malfait}, Jolien and {De Ceuster}, Frederik and {Ceulemans}, Thomas and {Donn{\'e}}, Dion and {Esseldeurs}, Mats and {Decin}, Leen},
title = {{Route towards complete 3D hydro-chemical simulations of companion-perturbed AGB outflows}},
keywords = {Stars: AGB, Stars: winds, outflows, Methods: numerical, Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies},
booktitle = {The Origin of Outflows in Evolved Stars},
year = {2022},
volume = {366},
month = jan,
pages = {227-233},
doi = {10.1017/S1743921322000217},
archiveprefix = {arXiv},
eprint = {2206.12278},
primaryclass = {astro-ph.SR},
adsurl = {https://ui.adsabs.harvard.edu/abs/2022IAUS..366..227M},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
Low- and intermediate mass stars experience a significant mass loss during the last phases of their evolution, which obscures them in a vast, dusty envelope. Although it has long been thought this envelope is generally spherically symmetric in shape, recent high-resolution observations find that most of these stars exhibit complex and asymmetrical morphologies, most likely resulting from binary interaction. In order to improve our understanding about these systems, theoretical studies are needed in the form of numerical simulations. Currently, a handful of simulations exist, albeit they mainly focus on the hydrodynamics of the outflow. Hence, we here present the pathway to more detailed and accurate modelling of companion-perturbed outflows with, by discussing the missing but crucial physical and chemical processes. With these state-of-the-art simulations we aim to make a direct comparison with observations to unveil the true identity on the embedded systems.