arXiv subjects

Skylar D'Angiolillo

Publications and source records attributed to Skylar D'Angiolillo.

5 recordsLinked to original sources

arXiv2026

A Century of Radial Velocity and Astrometric Monitoring of 70 Oph AB: New PFS Data and Constraints on Planetary Companions

At a distance of 5.1 pc, the 70 Oph AB binary star system is one of the most favorable targets for future direct imaging and astrometry missions surveying mature, terrestrial planets. We present new radial velocities (RVs) obtained with the Planet Finder Spectrograph (PFS) on the 6.5\,m Magellan II Clay Telescope in Chile. We collected 499 measurements of 70 Oph A and 334 measurements of 70 Oph B during 2023--2025. Combining these data with decades of archival RVs and astrometry, we derive an updated orbital solution for the binary and dynamical masses of $0.88 \pm 0.004\,M_\odot$ and $0.73 \pm 0.003\,M_\odot$ for the primary and secondary components, respectively. We find that the long-term RV variability of both components is consistent with stellar activity modulated by rotation periods, and we detect no coherent planetary signals in either component. We place upper limits on any planets orbiting in the plane of the binary. The 27 yr RV baseline for 70 Oph A excludes Jupiter-mass planets interior to 5 au and reaches a sensitivity of $0.3\,M_{\rm Jup}$ at 1 au or $0.5\,M_{\rm Jup}$ at 2 au. For 70 Oph B, with PFS data we rule out planets more massive than $0.25$--$0.3\,M_{\rm Jup}$ inside 0.5 au. We show that stable S-type orbits around 70 Oph A extend to $\sim2.5$ au, covering the habitable zone. Thus, Saturn-mass planets or smaller on stable orbits in the habitable zone of 70 Oph A are allowed. Overall, our results provide important guidance for future planet searches around this stellar system.

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arXiv2026

Accounting for Transit Timing Detectability: Biases in Planetary Radius and Orbital Period

Transit Timing Variations (TTVs) are deviations from the time an observer would expect to see an exoplanet transit its host star. In multi-planetary systems, significant TTVs may indicate the presence of another body in the system gravitationally interacting with the transiting exoplanet. T. Holczer et al. (2016) catalogs 2599 Kepler Objects of Interest (KOIs) and provides a statistical analysis of their TTVs for candidates that have transited at least seven times. However, this conservative limit on the number of transits neglects long-period KOIs. Therefore, we extend the statistical analysis performed by T. Holczer et al. (2016) to the population of KOIs that have between three and six transits. We identify six KOIs, three of which have Kepler names (Kepler-103 c, Kepler-90 g, and Kepler-1662 c), with significant TTV signals that were originally overlooked by T. Holczer et al. (2016). Additionally, we search for trends regarding the planetary radius and orbital period of KOIs with significant TTVs. Through a survival analysis, we determine that planets with shorter orbital periods require larger TTV signals to be detected compared to longer period planets, regardless of planetary size. Uncovering trends in TTV statistics such as this one will provide targets for future forward modeling of planetary architectures.

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arXiv2026

Mars as an Exoplanet: Lessons from a Planet at the Edge of Habitability

Mars is the Solar System's canonical small, rocky planet that transitioned from early geologic activity and surface liquid water to a cold and arid planet with a thin, cold, CO$_2$-dominated atmosphere. The evolution of Mars, in the context of such planetary parameters as size, mass, atmosphere, insolation flux, magnetosphere, and impact history, harbor important diagnostics regarding the development and sustainability of habitable surface conditions. In this work, we synthesize how the study of Mars contributes to our understanding of exoplanet processes, such as volatile delivery and loss, photochemistry, climate evolution (including CO$_2$ condensation and atmospheric loss), obliquity forcing, planetary architecture, and the role of intrinsic magnetism. We also evaluate optimal methods and prospects for detecting and characterizing potential Mars analogs beyond the Solar System. We focus on relevant results from planetary missions (e.g., Mars Reconnaissance Orbiter, MAVEN, Mars Science Laboratory, Mars2020) and observational studies of exoplanet atmospheres with the James Webb Space telescope (JWST) and future facilities. Through the convergence of these parallel pathways of inquiry, we describe the primary science questions and suggested avenues for characterizing small rocky planets that lie at the edge of potentially habitable conditions.

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arXiv2025

No Giant Planets in the Eta Cassiopeiae System: Dynamical Implications of a Wide Binary Companion

Given the vast number of stars that exist within binary systems, it remains important to explore the effect of binary star environments on the formation and evolution of exoplanetary systems. Nearby binaries provide opportunities to characterize their properties and orbits through a combination of radial velocities, astrometry, and direct imaging. Eta Cassiopeiae is a bright, well-known binary system for which recent observations have provided greatly improved stellar masses and orbital parameters. We present additional radial velocity data that are used to perform an injection-recovery analysis for potential planetary signatures. We further provide a detailed dynamical study that explores the viability of planetary orbits throughout the system. Our combined analysis shows that giant planets are significantly ruled out for the system, and indeed no planetary orbits are viable beyond $\sim$8 AU of the primary star. However, terrestrial planets may yet exist within the Habitable Zone where orbits can remain long-term stable. We discuss the implications of these results, highlighting the effect of wide binary companions on giant planet formation, and the consequences for occurrence rates and planetary habitability.

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arXiv2023

exoMMR: a New Python Package to Confirm and Characterize Mean Motion Resonances

The study of orbital resonances allows for the constraint of planetary properties of compact systems. We can predict a system's resonances by observing the orbital periods of the planets, as planets in or near mean motion resonance have period ratios that reduce to a ratio of small numbers. However, a period ratio near commensurability does not guarantee a resonance; we must study the system's dynamics and resonant angles to confirm resonance. Because resonances require in-depth study to confirm, and because two-body resonances require a measurement of the eccentricity vector which is quite challenging, very few resonant pairs or chains have been confirmed. We thus remain in the era of small number statistics, not yet able to perform large population synthesis or informatics studies. To address this problem, we build a python package to find, confirm, and analyze mean motion resonances, primarily through N-body simulations. We then analyze all near-resonant planets in the Kepler/K2 and TESS catalogues, confirming over 60 new resonant pairs and various new resonant chains. We additionally demonstrate the package's functionality and potential by characterizing the mass-eccentricity degeneracy of Kepler-80g, exploring the likelihood of an exterior giant planet in Kepler-80, and constraining the masses of planets in Kepler-305. We find that our methods overestimate the libration amplitudes of the resonant angles and struggle to confirm resonances in systems with more than three planets. We identify various systems that are likely resonant chains but that we are unable to confirm, and highlight next steps for exoplanetary resonances.

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