arXiv subjects

M. Esseldeurs

Publications and source records attributed to M. Esseldeurs.

8 recordsLinked to original sources

arXiv2026

The fate of Earth during the Sun's giant phases: New constraints from ab initio tidal modelling and AGB mass loss

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. We reassess the survival of the Earth and the inner Solar System planets during the entire evolution of the Sun, focusing on the impact of updated tidal dissipation prescriptions and varying AGB mass-loss rates. We modelled the orbital evolution of the Earth using stellar evolution tracks for a solar-mass star. 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. 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 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. 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 giant phases.

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arXiv2026

CORALIE radial-velocity search for companions around evolved stars (CASCADES) V. Three planetary companions and achievable precision

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.

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arXiv2026

Competition between gravity waves excited by convection and tides in stars that host a companion

Asteroseismology has become a powerful tool in stellar astrophysics, offering unprecedented insights into the internal structures and dynamics of stars. It enables precise characterization of stellar interiors across a wide range of stellar masses and of evolutionary phases, from the main sequence to the white dwarf phase. At the same time, the number of detected close stellar and planetary companions throughout the entire stellar evolutionary phases has increased significantly, prompting key questions about the interplay between stellar evolution and binarity. We investigate the competition between gravity waves (IGW) 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 IGWs stochastically excited by convection and by tides, we seek to quantify their relative contributions and identify the key parameters that govern their efficiency. We compute 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 of the radiative layers of the host star. 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. 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 IGW-driven angular momentum transport in stars that host a companion.

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arXiv2025

ATOMIUM: Continuum emission and evidence of dust enhancement from binary motion

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 1.2 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 elongated 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.

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arXiv2025

An accreting dwarf star orbiting the S-type giant star pi1 Gru

Aims. We aim to characterize the properties of the inner companion of the S-type AGB star pi1 Gru and to identify plausible future evolutionary 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. In June-July 2019, the inner companion, pi1 Gru C, was located at 37.4 +/- 2.0 mas from the primary (a projected separation of 6.05 +/- 0.55 au at 161.7 +/- 11.7 pc). The best orbital solution yields 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, corresponding to an orbital period of 11.0 (+1.7/-1.5) yr. The preferred solution is an elliptical orbit with eccentricity e = 0.35(+0.18/-0.17), although a circular orbit cannot be fully excluded. The close companion could be either a K1V (F9.5V to K7V) star or a white dwarf (WD). Ultraviolet and millimeter continuum photometry are consistent with the presence of an accretion disk around the close companion. The ultraviolet emission may originate from hot spots in an overall cooler disk, or from a hot disk if the companion is a WD. Conclusions. Although 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 trigger a Type Ia supernova, but it could produce novae every ~900 yr. Short-wavelength, spatially resolved observations are required to further constrain the nature of the C companion. Searches for close-in companions similar to this system will improve our understanding of the physics of mass and angular momentum transfer, as well as orbital evolution during late evolutionary stages.

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arXiv2025

Binarity at LOw Metallicity (BLOeM): Bayesian inference of natal kicks from inert black hole binaries

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.

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arXiv2024

Tidal Dissipation in Evolved Low and Intermediate Mass Stars

As the observed occurrence for planets or stellar companions orbiting low and intermediate-mass evolved stars is increasing, so does the importance of understanding and evaluating the strength of their interactions. One of the fundamental mechanisms to understand this interaction is the tidal dissipation in these stars, as it is one of the engines of orbital/rotational evolution of star-planet/star-star systems. This article builds on previous works studying the evolution of the tidal dissipation along the pre-MS and the MS, which have shown the 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. Using stellar evolutionary models, the internal structure of the star is computed from the pre-MS all the way up to the white dwarf phase, for stars with initial mass between 1 and 4 Msun. Tidal dissipation is separated into two components: the dissipation of the equilibrium (non-wavelike) tide and the dissipation of the dynamical (wavelike) tide. For evolved stars the dynamical tide is constituted by progressive internal gravity waves. 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 in size or the companion is far away from the star. Conversely the dissipation of the dynamical tide is important when the star is small in size or the companion is close to the star. 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 planetary or/and stellar companions orbiting them.

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arXiv2023

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

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. 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. 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. 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...

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