Examinando por Autor "Cuadra, Jorge"

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    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.
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    Long Live the Disk: Lifetimes of Protoplanetary Disks in Hierarchical Triple-star Systems and a Possible Explanation for HD 98800 B
    (American Astronomical Society (Aas), 2021) Ronco, María Paula; Guilera, Octavio M.; Cuadra, Jorge; Miller Bertolami, Marcelo M.; Nicolás Cuello; Fontecilla, Camilo; Poblete, Pedro; Bayo, Amelia
    The gas dissipation from a protoplanetary disk is one of the key processes affecting planet formation, and it is widely accepted that it happens on timescales of a few million years for disks around single stars. In recent years, several protoplanetary disks have been discovered in multiple-star systems, and despite the complex environment in which they find themselves, some of them seem to be quite old, a situation that may favor planet formation. A clear example of this is the disk around HD 98800 B, a binary in a hierarchical quadruple stellar system, which at an ∼10 Myr age seems to still be holding significant amounts of gas. Here we present a 1D+1D model to compute the vertical structure and gas evolution of circumbinary disks in hierarchical triple-star systems considering different stellar and disk parameters. We show that tidal torques due to the inner binary, together with the truncation of the disk due to the external companion, strongly reduce the viscous accretion and expansion of the disk. Even allowing viscous accretion by tidal streams, disks in these kind of environments can survive for more than 10 Myr, depending on their properties, with photoevaporation being the main gas dissipation mechanism. We particularly apply our model to the circumbinary disk around HD 98800 B and confirm that its longevity, along with the current nonexistence of a disk around the companion binary HD 98800 A, can be explained with our model and by this mechanism.
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    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, Clément
    Planets 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.