Examinando por Autor "Olofsson, Johan"
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Ítem A near-infrared interferometric survey of debris-disk stars VII. The hot-to-warm dust connection(European Southern Observatory (ESO), 2021) Absil, O.; Marion, L.; Ertel, S.; Defrère, D.; Kennedy, G. M.; Romagnolo, A.; Le Bouquin, J.-B.; Christiaens, V.; Milli, J.; Bonsor, A.; Olofsson, Johan; Su, K. Y. L.; Augereau, J.-C.Context. Hot exozodiacal dust has been shown to be present in the innermost regions of an increasing number of main sequence stars over the past 15 yr. However, the origin of hot exozodiacal dust and its connection with outer dust reservoirs remains unclear. Aims. We aim to explore the possible connection between hot exozodiacal dust and warm dust reservoirs (≥100 K) in asteroid belts. Methods. We use precision near-infrared interferometry with VLTI/PIONIER to search for resolved emission at H-band around a selected sample of 62 nearby stars that show possible signs of warm dust populations. Results. Our observations reveal the presence of resolved near-infrared emission around 17 out of 52 stars with sufficient data quality. For four of these, the emission is shown to be due to a previously unknown stellar companion. The 13 other H-band excesses are thought to originate from the thermal emission of hot dust grains, close to their sublimation temperature. Taking into account earlier PIONIER observations, where some stars with warm dust were also observed, and after re-evaluating the warm dust content of all our PIONIER targets through spectral energy distribution modeling, we find a detection rate of 17.1−4.6+8.1% for H-band excess around main sequence stars hosting warm dust belts, which is statistically compatible with the occurrence rate of 14.6−2.8+4.3% found around stars showing no signs of warm dust. After correcting for the sensitivity loss due to partly unresolved hot disks, under the assumption that they are arranged in a thin ring around their sublimation radius, we find tentative evidence at the 3σ level that H-band excesses around stars with outer dust reservoirs (warm or cold) could be statistically larger than H-band excesses around stars with no detectable outer dust. Conclusions. Our observations do not suggest a direct connection between warm and hot dust populations at the sensitivity level of the considered instruments, although they bring to light a possible correlation between the level of H-band excess and the presence of outer dust reservoirs in general.Ítem The challenge of measuring the phase function of debris disks: Application to HR4796(European Southern Observatory, 2020) Olofsson, Johan; Bayo, AmeliaContext. Debris discs are valuable systems to study dust properties. Because they are optically thin at all wavelengths, we have direct access to the absorption and scattering properties of the dust grains. One very promising technique to study them is to measure their phase function, that is, the scattering efficiency as a function of the scattering angle. Discs that are highly inclined are promising targets as a wider range of scattering angles can be probed. Aims. The phase function (polarised or total intensity) is usually either inferred by comparing the observations to synthetic disc models, assuming a parametrised phase function or estimating it from the surface brightness of the disc. Here, we argue that the latter approach can be biased due to projection effects leading to an increase in column density along the major axis of a non-flat disc. Methods. We present a novel approach to account for those column density effects. The method remains model dependent, as a disc model is still required to estimate the density variations as a function of the scattering angle. This method allows us, however, to estimate the shape of the phase function without having to invoke any parametrised form. Results. We apply our method to SPHERE/ZIMPOL observations of HR 4796 A and highlight the differences with previous measurements only using the surface brightness; the main differences being at scattering angles smaller than ~100°. Our modelling results suggest that the disc is not vertically flat at optical wavelengths; this result is supported by comparing the width along the major and minor axis of synthetic images. We discuss some of the caveats of the approach, mostly that our method remains blind to real local increases in the dust density and that it cannot be readily applied to angular differential imaging observations yet. Conclusions. We show that the vertical thickness of inclined (≥60°) debris discs can affect the determination of their phase functions. Similarly to previous studies on HR 4796 A, we still cannot reconcile the full picture using a given scattering theory to explain the shape of the phase function, the blow-out size due to radiation pressure, and the shape of the spectral energy distribution, which is a long-lasting problem for debris discs. Nonetheless, we argue that similar effects, such as the ones highlighted in this study, can also bias the determination of the phase function in total intensity.Ítem Characterizing the morphology of the debris disk around the low-mass star GSC 07396-00759(European Southern Observatory (ESO), 2021) Adam, C.; Olofsson, Johan; Van Holstein, R. G.; Bayo, Amelia; Milli, J.; Boccaletti, A.; Kral, Q.; Ginski, C.; Henning, Th.; Montesinos, M.; Pawellek, N.; Zurlo, A.; Langlois, M.; Delboulbé, A.; Pavlov, A.; Ramos, J.; Weber, L.; Wildi, F.; Rigal, F.; Sauvage, J.-F.Context. Debris disks have commonly been studied around intermediate-mass stars. Their intense radiation fields are believed to efficiently remove the small dust grains that are constantly replenished by collisions. For lower-mass central objects, in particular M stars, the dust removal mechanism needs to be further investigated given the much weaker radiation field produced by these objects. Aims. We present new observations of the nearly edge-on disk around the pre-main-sequence M-type star GSC 07396-00759, taken with VLT/SPHERE IRDIS in dual-beam polarimetric imaging mode, with the aim to better understand the morphology of the disk, its dust properties, and the star-disk interaction via the stellar mass-loss rate. Methods. We model the polarimetric observations to characterize the location and properties of the dust grains using the Henyey–Greenstein approximation of the polarized phase function. We use the estimated phase function to evaluate the strength of the stellar winds. Results. We find that the polarized light observations are best described by an extended and highly inclined disk (i ≈ 84.3 ° ± 0.3) with a dust distribution centered at a radius r0 ≈ 107 ± 2 au. Our modeling suggests an anisotropic scattering factor g ≈ 0.6 to best reproduce the polarized phase function S12. We also find that the phase function is reasonably well reproduced by small micron-sized dust grains with sizes s > 0.3μm. We discuss some of the caveats of the approach, mainly that our model probably does not fully recover the semimajor axis of the disk and that we cannot readily determine all dust properties due to a degeneracy between the grain size and the porosity. Conclusions. Even though the radius of the disk may be overestimated, our best-fit model not only reproduces the observations well but is also consistent with previous published data obtained in total intensity. Similarly to previous studies of debris disks, we suggest that using a given scattering theory might not be sufficient to fully explain key aspects, such as the shape of the phase function or the dust grain size. Taking into consideration the aforementioned caveats, we find that the average mass-loss rate of GSC 07396-00759 can be up to 500 times stronger than that of the Sun, supporting the idea that stellar winds from low-mass stars can evacuate small dust grains in an efficient way.Ítem Cronomoons: origin, dynamics, and light-curve features of ringed exomoons(Royal Astronomical Society, 2022) Sucerquia, Mario; Alvarado-Montes, Jaime A.; Bayo, Amelia; Cuadra, Jorge; Cuello, Nicolás; Giuppone, Cristian A.; Montesinos, Matías; Olofsson, Johan; Schwab, Christian; Spitler, Lee; Zuluaga, Jorge I.In recent years, technical and theoretical work to detect moons and rings around exoplanets has been attempted. The small mass/size ratios between moons and planets means this is very challenging, having only one exoplanetary system where spotting an exomoon might be feasible (i.e. Kepler-1625b i). In this work, we study the dynamical evolution of ringed exomoons, dubbed cronomoons after their similarity with Cronus (Greek for Saturn), and after Chronos (the epitome of time), following the Transit Timing Variations and Transit Duration Variation that they produce on their host planet. Cronomoons have extended systems of rings that make them appear bigger than they actually are when transiting in front of their host star. We explore different possible scenarios that could lead to the formation of such circumsatellital rings, and through the study of the dynamical/thermodynamic stability and lifespan of their dust and ice ring particles, we found that an isolated cronomoon can survive for time-scales long enough to be detected and followed up. If these objects exist, cronomoons’ rings will exhibit gaps similar to Saturn’s Cassini Division and analogous to the asteroid belt’s Kirkwood gaps but instead raised due to resonances induced by the host planet. Finally, we analyse the case of Kepler-1625b i under the scope of this work, finding that the controversial giant moon could instead be an Earth-mass cronomoon. From a theoretical perspective, this scenario can contribute to a better interpretation of the underlying phenomenology in current and future observations.Ítem Debris discs in binaries: morphology and photometric signatures?(European Southern Observatory (ESO), 2021) Thebault, P.; Kral, Q.; Olofsson, JohanContext. Since about half of all main-sequence stars reside in multiple star systems, it is important to consider the effect of binarity on the evolution of planetesimal belts in these complex systems. Aims. We aim to see whether debris belts evolving between two stars may be impacted by the presence of the companion and whether this leaves any detectable signature that could be observed with current or future instruments. Methods. We consider a circumprimary parent body (PB) planetesimal belt that is placed just inside the stability limit between the two stars and we use the state-of-the-art DyCoSS code to follow the coupled dynamical and collisional evolution of the dust produced by this PB belt. We explore several free parameters, such as the belt’s mass and the binary’s mass ratio as well as its orbital eccentricity. We use the GraTeR package to produce 2D luminosity maps and system-integrated spectral energy distributions (SEDs). Results. We confirm a preliminary result obtained by previous DyCoSS studies, which is that the coupled effect of collisional activity, binary perturbations, and stellar radiation pressure is able to place and maintain a halo of small grains in the dynamically unstable region between the two stars. In addition, we identify several prominent spatial structures, notably, a single spiral arm stretching all the way from the PB belt to the companion star. We also identify a fainter and more compact disc around the secondary star, which is non-native and feeds off small grains from the unstable halo. The halo, spiral arm, and secondary disc should all be detectable on resolved images by instruments with capacities on the level of SPHERE. The system as a whole is depleted of small grains when compared to a companion-free case. This depletion leaves an imprint on the system’s integrated SED, which appears colder than for the same parent body belt around a single star. This new finding could explain why the SED-derived location, rdisc, of some unresolved discs-in-binaries places their primary belt in the dynamically ’forbidden’ region between the two stars: indeed, this apparent paradox could be due to an overestimation of rdisc when using empirical prescriptions that are valid for the case of a single star.Ítem Dust trapping around Lagrangian points in protoplanetary disks(European Southern Observatory, 2020) Montesinos, Matías; Olofsson, Johan; Bayo, Amelia; Sucerquia, MarioAims. Trojans are defined as objects that share the orbit of a planet at the stable Lagrangian points L4 and L5. In the Solar System, these bodies show a broad size distribution ranging from micrometer (μm) to centimeter (cm) particles (Trojan dust) and up to kilometer (km) rocks (Trojan asteroids). It has also been theorized that earth-like Trojans may be formed in extra-solar systems. The Trojan formation mechanism is still under debate, especially theories involving the effects of dissipative forces from a viscous gaseous environment. Methods. We perform hydro-simulations to follow the evolution of a protoplanetary disk with an embedded 1–10 Jupiter-mass planet. On top of the gaseous disk, we set a distribution of μm–cm dust particles interacting with the gas. This allows us to follow dust dynamics as solids get trapped around the Lagrangian points of the planet. Results. We show that large vortices generated at the Lagrangian points are responsible for dust accumulation, where the leading Lagrangian point L4 traps a larger amount of submillimeter (submm) particles than the trailing L5, which traps mostly mm–cm particles. However, the total bulk mass, with typical values of ~Mmoon, is more significant in L5 than in L4, in contrast to what is observed in the current Solar System a few gigayears later. Furthermore, the migration of the planet does not seem to affect the reported asymmetry between L4 and L5. Conclusions. The main initial mass reservoir for Trojan dust lies in the same co-orbital path of the planet, while dust migrating from the outer region (due to drag) contributes very little to its final mass, imposing strong mass constraints for the in situ formation scenario of Trojan planets.Ítem Highly Structured Inner Planetary System Debris around the Intermediate Age Sun-like Star TYC 8830 410 1(American Astronomical Society, 2021) Melis, Carl; Olofsson, Johan; Song, Inseok; Sarkis, Paula; Weinberger, Alycia J.; Kennedy, Grant; Krumpe, MirkoWe present a detailed characterization of the extremely dusty main-sequence star TYC 8830 410 1. This system hosts inner planetary system dust (Tdust ≈ 300 K) with a fractional infrared luminosity of ∼1%. Mid-infrared spectroscopy reveals a strong, mildly crystalline solid-state emission feature. TYC 8830 410 1 (spectral type G9 V) has a 49.5″ separation M4-type companion comoving and co-distant with it, and we estimate a system age of ∼600 Myr. TYC 8830 410 1 also experiences “dipper”-like dimming events as detected by the All-Sky Automated Survey for Supernovae, Transiting Exoplanet Survey Satellite, and characterized in more detail with the Las Cumbres Observatory Global Telescope. These recurring eclipses suggest at least one roughly star-sized cloud of dust orbits the star in addition to assorted smaller dust structures. The extreme properties of the material orbiting TYC 8830 410 1 point to dramatic dust-production mechanisms that likely included something similar to the giant impact event thought to have formed the Earth–Moon system, although hundreds of millions of years after such processes are thought to have concluded in the solar system. TYC 8830 410 1 holds promise to deliver significant advances in our understanding of the origin, structure, and evolution of extremely dusty inner planetary systems.Ítem NaCo polarimetric observations of Sz 91 transitional disc: a remarkable case of dust filtering(Royal Astronomical Society, 2020) Mauco, Karina; Olofsson, Johan; Schreiber, Matthias R.; Bayo, Amelia; Cáceres, Claudio; Montesinos, MatíasWe present polarized light observations of the transitional disc around Sz 91 acquired with VLT/NaCo at H (1.7μm) and Ks (2.2μm) bands. We resolve the disc and detect polarized emission up to ∼0.5 arcsec (∼80 au) along with a central cavity at both bands. We computed a radiative transfermodel that accounts for themain characteristics of the polarized observations. We found that the emission is best explained by small, porous grains distributed in a disc with a ∼45 au cavity. Previous ALMA observations have revealed a large sub-mm cavity (∼83 au) and extended gas emission from the innermost (<16 au) regions up to almost 400 au from the star. Dynamical clearing by multiple low-mass planets arises as the most probable mechanism for the origin of Sz 91’s peculiar structure. Using new L -band ADI observations, we can rule out companions more massive than Mp ≥ 8 MJup beyond 45 au assuming hot-start models. The disc is clearly asymmetric in polarized light along the minor axis, with the north side brighter than the south side. Differences in position angle between the disc observed at sub-mm wavelengths with ALMA and our NaCo observations were found. This suggests that the disc around Sz 91 could be highly structured. Higher signal-to-noise near-IR and sub-mm observations are needed to confirm the existence of such structures and to improve the current understanding of the origin of transitional discs.Ítem Radiative Scale Height and Shadows in Protoplanetary Disks(American Astronomical Society (Aas), 2021) Montesinos, Matías; Cuello, Nicolás; Olofsson, Johan; Cuadra, Jorge; Bayo, Amelia; H.-M. Bertrang, Gesa; Perrot, ClémentPlanets form in young circumstellar disks called protoplanetary disks. However, it is still difficult to catch planet formation in situ. Nevertheless, from recent ALMA/SPHERE data, encouraging evidence of the direct and indirect presence of embedded planets has been identified in disks around young stars: co-moving point sources, gravitational perturbations, rings, cavities, and emission dips or shadows cast on disks. The interpretation of these observations needs a robust physical framework to deduce the complex disk geometry. In particular, protoplanetary disk models usually assume the gas pressure scale height given by the ratio of the sound speed over the azimuthal velocity H/r = cs/vk. By doing so, radiative pressure fields are often ignored, which could lead to a misinterpretation of the real vertical structure of such disks. We follow the evolution of a gaseous disk with an embedded Jupiter-mass planet through hydrodynamical simulations, computing the disk scale height including radiative pressure, which was derived from a generalization of the stellar atmosphere theory. We focus on the vertical impact of the radiative pressure in the vicinity of circumplanetary disks, where temperatures can reach ≳1000 K for an accreting planet and radiative forces can overcome gravitational forces from the planet. The radiation pressure effects create a vertical, optically thick column of gas and dust at the protoplanet location, casting a shadow in scattered light. This mechanism could explain the peculiar illumination patterns observed in some disks around young stars such as HD 169142 where a moving shadow has been detected or the extremely high aspect ratio H/r ∼ 0.2 observed in systems like AB Aur and CT Cha.Ítem Revealing asymmetrical dust distribution in the inner regions of HD141569(European Southern Observatory (ESO), 2021) Singh, G.; Bhowmik, T.; Boccaletti, A.; Thébault, P.; Kral, Q.; Milli, J.; Mazoyer, J.; Pantin, E.; Van Holstein, R. G.; Olofsson, Johan; Boukrouche, R.; Di Folco, E.; Janson, M.; Langlois, M.; Maire, A.-L.; Vigan, A.; Benisty, M.; Augereau, J.-C.; Perrot, C.; Gratton, R.; Henning, T.; Ménard, F.; Rickman, E.; Wahhaj, Z.; Zurlo, A.; Biller, B.; Bonnefoy, M.; Chauvin, G.; Delorme, P.; Desidera, S.; D’Orazi, V.; Feldt, M.; Hagelberg, J.; Keppler, M.; Kopytova, T.; Lagadec, E.; Lagrange, A.-M.; Mesa, D.; Meyer, M.; Rouan, D.; Sissa, E.; Schmidt, T. O. B.; Jaquet, M.; Fusco, T.; Pavlov, A.; Rabou, P.Context. The combination of high-contrast imaging with spectroscopy and polarimetry offers a pathway to studying the grain distribution and properties of debris disks in exquisite detail. Here, we focus on the case of a gas-rich debris disk around HD 141569A, which features a multiple-ring morphology first identified with SPHERE in the near-infrared. Aims. We obtained polarimetric differential imaging with SPHERE in the H-band to compare the scattering properties of the innermost ring at 44 au with former observations in total intensity with the same instrument. In polarimetric imaging, we observed that the intensity of the ring peaks in the south-east, mostly in the forward direction, whereas in total intensity imaging, the ring is detected only at the south. This noticeable characteristic suggests a non-uniform dust density in the ring. With these two sets of images, we aim to study the distribution of the dust to solve for the actual dust distribution. Methods. We implemented a density function varying azimuthally along the ring and generated synthetic images both in polarimetry and in total intensity, which are then compared to the actual data. The search for the best-fit model was performed both with a grid-based and an MCMC approach. Using the outcome of this modelization, we further measured the polarized scattering phase function for the observed scattering angle between 33° and 147° as well as the spectral reflectance of the southern part of the ring between 0.98 and 2.1 μm. We tentatively derived the grain properties by comparing these quantities with MCFOST models and assuming Mie scattering. Results. We find that the dust density peaks in the south-west at an azimuthal angle of 220°~238° with a rather broad width of 61°~127°. The difference in the intensity distributions observed in polarimetry and total intensity is the result of this particular morphology. Although there are still uncertainties that remain in the determination of the anisotropic scattering factor, the implementation of an azimuthal density variation to fit the data proved to be robust. Upon elaborating on the origin of this dust density distribution, we conclude that it could be the result of a massive collision when we account for the effect of the high gas mass that is present in the system on the dynamics of grains. In terms of grain composition, our preliminary interpretation indicates a mixture of porous sub-micron sized astro-silicate and carbonaceous grains. Conclusions. The SPHERE observations have allowed, for the first time, for meaningful constraints to be placed on the dust distribution beyond the standard picture of a uniform ring-like debris disk. However, future studies with a multiwavelength approach and additional detailed modeling would be required to better characterize the grain properties in the HD 141569 system.Ítem Search for associations containing young stars (SACY) VIII. An updated census of spectroscopic binary systems exhibiting hints of non-universal multiplicity among their associations(European Southern Observatory (ESO), 2021) Zúñiga-Fernández, S.; Bayo, Amelia; Elliott, P.; Zamora, C.; Corvalán, G.; Haubois, X.; Corral-Santana, J. M.; Olofsson, Johan; Huélamo, N.; Sterzik, M. F.; Torres, C. A. O.; Quast, G. R.; Melo, C. H. F.Context. Nearby young associations offer one of the best opportunities for a detailed study of the properties of young stellar and substellar objects thanks to their proximity (<200 pc) and age (∼5−150 Myr). Previous works have identified spectroscopic (<5 au) binaries, close (5−1000 au) visual binaries, and wide or extremely wide (1000−100 000 au) binaries in the young associations. In most of the previous analyses, single-lined spectroscopic binaries (SB1) were identified based on radial velocities variations. However, this apparent variation may also be caused by mechanisms unrelated to multiplicity. Aims. We seek to update the spectroscopy binary fraction of the Search for Associations Containing Young stars (SACY) sample, taking into consideration all possible biases in our identification of binary candidates, such as activity and rotation. Methods. Using high-resolution spectroscopic observations, we produced ∼1300 cross-correlation functions (CCFs) to disentangle the previously mentioned sources of contamination. The radial velocity values we obtained were cross-matched with the literature and then used to revise and update the spectroscopic binary (SB) fraction in each object of the SACY association. In order to better describe the CCF profile, we calculated a set of high-order cross-correlation features to determine the origin of the variations in radial velocities. Results. We identified 68 SB candidates from our sample of 410 objects. Our results hint that at the possibility that the youngest associations have a higher SB fraction. Specifically, we found sensitivity-corrected SB fractions of 22−11+15% for ϵ Cha, 31−14+16% for TW Hya and 32−8+9% for β Pictoris, in contrast to the five oldest associations we have sampled (∼35−125 Myr) which are ∼10% or lower. This result seems independent of the methodology used to asses membership to the associations. Conclusions. The new CCF analysis, radial velocity estimates, and SB candidates are particularly relevant for membership revision of targets in young stellar associations. These targets would be ideal candidates for follow-up campaigns using high-resolution techniques to confirm binarity, resolve orbits, and, ideally, calculate dynamical masses. Additionally, if the results on the SB fraction in the youngest associations were confirmed, it could hint at a non-universal multiplicity among SACY associations.Ítem The Characterization of the Dust Content in the Ring Around Sz 91: Indications of Planetesimal Formation?(American Astronomical Society, 2021) Maucó, Karina; Carrasco-González, Carlos; Schreiber, Matthias R.; Sierra, Anibal; Olofsson, Johan; Bayo, Amelia; Caceres, Claudio; Canovas, Hector; Palau, AinaOne of the most important questions in the field of planet formation is how millimeter- and centimeter-sized dust particles overcome radial drift and fragmentation barriers to form kilometer-sized planetesimals. ALMA observations of protoplanetary disks, in particular transition disks or disks with clear signs of substructures, can provide new constraints on theories of grain growth and planetesimal formation, and therefore represent one possibility for progress on this issue. We here present ALMA band 4 (2.1 mm) observations of the transition disk system Sz 91, and combine them with previously obtained band 6 (1.3 mm) and band 7 (0.9 mm) observations. Sz 91, with its well-defined millimeter ring, more extended gas disk, and evidence of smaller dust particles close to the star, constitutes a clear case of dust filtering and the accumulation of millimeter-sized particles in a gas pressure bump. We compute the spectral index (nearly constant at ∼3.34), optical depth (marginally optically thick), and maximum grain size (∼0.61 mm) in the dust ring from the multi-wavelength ALMA observations, and compare the results with recently published simulations of grain growth in disk substructures. Our observational results are in strong agreement with the predictions of models for grain growth in dust rings that include fragmentation and planetesimal formation through streaming instability.Ítem The HD 98800 quadruple pre-main sequence system Towards full orbital characterisation using long-baseline infrared interferometry(European Southern Observatory (ESO), 2021) Zúñiga-Fernández, S.; Olofsson, Johan; Bayo, Amelia; Haubois, X.; Corral-Santana, J. M.; Lopera-Mejía, A.; Ronco, M. P.; Tokovinin, A.; Gallenne, A.; Kennedy, G. M.; Berger, J.-P.Context. HD 98800 is a young (∼10 Myr old) and nearby (∼45 pc) quadruple system, composed of two spectroscopic binaries orbiting around each other (AaAb and BaBb), with a gas-rich disk in polar configuration around BaBb. While the orbital parameters of BaBb and AB are relatively well constrained, this is not the case for AaAb. A full characterisation of this quadruple system can provide insights on the formation of such a complex system. Aims. The goal of this work is to determine the orbit of the AaAb subsystem and refine the orbital solution of BaBb using multi-epoch interferometric observations with the Very Large Telescope Interferometer PIONIER and radial velocities. Methods. The PIONIER observations provide relative astrometric positions and flux ratios for both AaAa and BaBb subsystems. Combining the astrometric points with radial velocity measurements, we determine the orbital parameters of both subsystems. Results. We refined the orbital solution of BaBb and derived, for the first time, the full orbital solution of AaAb. We confirmed the polar configuration of the circumbinary disk around BaBb. From our solutions, we also inferred the dynamical masses of AaAb (MAa = 0.93 ± 0.09 and MAb = 0.29 ± 0.02 M⊙). We also revisited the parameters of the AB outer orbit. Conclusions. The orbital parameters are relevant to test the long-term stability of the system and to evaluate possible formation scenarios of HD 98800. Using the N-body simulation, we show that the system should be dynamically stable over thousands of orbital periods and that it made preliminary predictions for the transit of the disk in front of AaAb which is estimated to start around 2026. We discuss the lack of a disk around AaAb, which can be explained by the larger X-ray luminosity of AaAb, promoting faster photo-evaporation of the disk. High-resolution infrared spectroscopic observations would provide radial velocities of Aa and Ab (blended lines in contemporary observations), which would allow us to calculate the dynamical masses of Aa and Ab independently of the parallax of BaBb. Further monitoring of other hierarchical systems will improve our understanding of the formation and dynamical evolution of these kinds of systems.