Browsing by Author "Espinoza Retamal, Juan Ignacio"

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    Constraining the Flatness of Planetary Systems
    (2025) Espinoza Retamal, Juan Ignacio; Aguilera Gómez, Claudia; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    Over the past 30 years, nearly 6,000 exoplanets have been discovered, revealing a remarkable diversity of planetary systems. Essential information about the formation of these systems can be found in their current architectures, as they serve as a signature of their dynamical evolution. Much of what we currently know about architectures comes from the study of stellar obliquities--the angle between the stellar spin axis and the planet's orbital normal--in hot Jupiter systems. However, hot Jupiters are intrinsically rare, with an occurrence rate of 1%, highlighting the need to explore architectures in a broader range of planetary systems. In this thesis, I study the architectures of planetary systems beyond hot Jupiters, focusing on warm Jupiter and Neptune systems through stellar obliquity measurements. Using VLT/ESPRESSO observations of the Rossiter-McLaughlin effect, I have found that these different exoplanet populations have different obliquity distributions: i) hot Jupiters show a two-component distribution, with one population of aligned systems and another approximately isotropic population of misaligned systems; ii) independent of their eccentricities, warm Jupiters are typically well aligned; iii) Neptunes appear to have a bimodal distribution of well-aligned and polar systems. These contrasting obliquity distributions suggest distinct formation pathways for each population. Finally, I also discuss prospects and make predictions for measuring mutual inclinations--the angle between different orbital planes of different planets in the same system--using future Gaia astrometric data. I show that these measurements have the potential to provide deeper insights into the formation and evolution of a larger and more diverse sample of planetary systems.
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    Gaia-4b and 5b: Radial Velocity Confirmation of Gaia Astrometric Orbital Solutions Reveal a Massive Planet and a Brown Dwarf Orbiting Low-mass Stars
    (IOP Publishing Ltd, 2025) Stefansson, Gudmundur; Mahadevan, Suvrath; Winn, Joshua N.; Marcussen, Marcus L.; Kanodia, Shubham; Albrecht, Simon; Fitzmaurice, Evan; Mikulskyte, One; Canas, Caleb I.; Espinoza Retamal, Juan Ignacio; Zwart, Yiri; Krolikowski, Daniel M.; Hotnisky, Andrew; Robertson, Paul; Alvarado-Montes, Jaime A.; Bender, Chad F.; Blake, Cullen H.; Callingham, J. R.; Cochran, William D.; Delamer, Megan; Diddams, Scott A.; Dong, Jiayin; Fernandes, Rachel B.; Giovinazzi, Mark R.; Halverson, Samuel; Libby-Roberts, Jessica; Logsdon, Sarah E.; Mcelwain, Michael W.; Ninan, Joe P.; Rajagopal, Jayadev; Reji, Varghese; Roy, Arpita; Schwab, Christian; Wright, Jason T.
    Gaia astrometry of nearby stars is precise enough to detect the tiny displacements induced by substellar companions, but radial velocity (RV) data are needed for definitive confirmation. Here we present RV follow-up observations of 28 M and K stars with candidate astrometric substellar companions, which led to the confirmation of two systems, Gaia-4b and Gaia-5b, identification of five systems that are single lined but require additional data to confirm as substellar companions, and the refutation of 21 systems as stellar binaries. Gaia-4b is a massive planet (M = 11.8 +/- 0.7 MJ) in a P = 571.3 +/- 1.4 day orbit with a projected semimajor axis a0 = 0.312 +/- 0.040 mas orbiting a 0.644 +/- 0.02M circle dot star. Gaia-5b is a brown dwarf (M = 20.9 +/- 0.5MJ) in a P = 358.62 +/- 0.20 days eccentric e = 0.6423 +/- 0.0026 orbit with a projected angular semimajor axis of a0 = 0.947 +/- 0.038 mas around a 0.34 +/- 0.03M circle dot star. Gaia-4b is one of the first exoplanets discovered via the astrometric technique, and is one of the most massive planets known to orbit a low-mass star.
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    The Spin–Orbit Alignment of Eight Warm Gas Giant Systems
    (American Astronomical Society, 2025) Espinoza Retamal, Juan Ignacio; Jordán Colzani, Andrés Cristóbal; Brahm Scott, Rafael; Petrovich Balbontín, Cristóbal; Sedaghati, Elyar; Stefánsson, Guðmundur; Hobson, Melissa J.; Tala Pinto, Marcelo Said; Muñoz, Diego J.; Boyle, Gavin; Leiva, Rodrigo; Suc, Vincent
    Essential information about the formation and evolution of planetary systems can be found in their architectures—in particular, in stellar obliquity (ψ)—as they serve as a signature of their dynamical evolution. Here we present ESPRESSO observations of the Rossiter–McLaughlin (RM) effect of eight warm gas giants, revealing that, independently of the eccentricities, all of them have relatively aligned orbits. Our five warm Jupiters (WASP-106 b, WASP-130 b, TOI-558 b, TOI-4515 b, and TOI-5027 b) have sky-projected obliquities |λ| ≃ 0–10°, while the two less massive warm Saturns (K2-139 b and K2-329 A b) are slightly misaligned, having |λ| ≃ 15–25°. Furthermore, for K2-139 b, K2-329 A b, and TOI-4515 b, we also measure true 3D obliquities ψ ≃ 15–30°. We also report a nondetection of the RM effect produced by TOI-2179 b. Through hierarchical Bayesian modeling of the true 3D obliquities of hot and warm Jupiters, we find that around single stars warm Jupiters are statistically more aligned than hot Jupiters. Independent of eccentricities, 95% of the warm Jupiters have ψ ≲ 25° with no misaligned planets, while hot Jupiters show an almost isotropic distribution of misaligned systems. This implies that around single stars warm Jupiters form in primordially aligned protoplanetary disks and subsequently evolve in a more quiescent way than hot Jupiters. Finally, we find that Saturns may have slightly more misaligned orbits than warm Jupiters, but more obliquity measurements are necessary to be conclusive.