arXiv subjects

Julia de Leon

Publications and source records attributed to Julia de Leon.

7 recordsLinked to original sources

arXiv2026

Kilometre-scale Jovian moon characterized for a potential JUICE flyby

Jupiter's irregular satellites are thought to be relics of early Solar System planetesimals. However, their small sizes, large distances from Earth and close angular proximity to Jupiter make them difficult to characterize remotely. Here we report multi-instrument observations of kilometre-sized Kallichore, the only irregular moon of Jupiter amenable to a close flyby by ESA's Jupiter Icy Moons Explorer (JUICE), whose astrometric and physical properties were still poorly constrained. We used Hubble photometry and astrometry, followed by a ground-based, multi-site stellar occultation campaign and astrometric and photometric observations with the 10.4-m Gran Telescopio Canarias. We reduced Kallichore's orbital uncertainty by up to approximately 80% and determined its shape: an elongated object with a minimum semi-axis ratio of a/b = 1.53 +/- 0.10, an area-equivalent diameter of 3.8 (+2.3/-0.3) km and a dark surface with a geometric albedo of 3.7% (+0.7/-2.2). No close companions were detected. These new constraints provide a viable pathway towards a JUICE flyby once the spacecraft arrives in the Jupiter system in 2031.

astro-ph.EP↗

arXiv2026

The Polana-Eulalia Complex with JWST NIRSpec: Connections to Bennu, Ryugu, and Outer Solar System Bodies

Carbon rich [C complex] asteroids provide insight into the early Solar System, and families of C complex asteroids serve as robust samples for learning about the internal structure of planetesimals and the materials of the protoplanetary disk. This work investigates the compositions of asteroids within the Polana Eulalia Complex [PEC] through analyses of JWST NIRSpec. Obtained as part of the Spectral Analysis of Main Belt Asteroids in the 3 um Region [SAMBA3] project. NIRSpec observations were conducted for the namesake asteroid of the Eulalia family, [495] Eulalia, as well as three members from the Polana family: [2441] Hibbs, [6712] Hornstein, and [6769] Brokoff. Analyses of the 2.7 um region demonstrate that PEC asteroids exhibit absorptions associated with Mg rich phyllosilicates, in turn underscoring high, though incomplete, degrees of aqueous alteration in the past for both PEC families. Although consistent in regard to composition, [142] Polana and [495] Eulalia show deeper 2.7 um bands than the Polana family asteroids, suggesting slight differences in the degrees of aqueous alteration between large and small PEC asteroids. Minor absorptions from 3.0 to 4.0 um indicate that [495] Eulalia's surface may contain more carbonates than [142] Polana, which potentially highlights slight differences between each family's formation and evolution. Additionally, PEC asteroids also show spectral consistency with Bennu and Ryugu, reinforcing their shared origin in the PEC. Minor absorptions in PEC asteroid spectra also connect to small bodies within and beyond the Main Belt, providing further evidence of outer Solar System formation for the PEC parent bodies.

astro-ph.EP↗

arXiv2021

Spectroscopic study of Ceres' collisional family candidates

Context: Despite the observed signs of large impacts on the surface of Ceres, there is no confirmed collisional family associated with this dwarf planet. After a dynamical and photometric study, a sample of 156 asteroids was proposed as candidate members of a Ceres collisional family. Aims: Our main objective is to study the connection between Ceres and a total of 14 observed asteroids among the candidate's sample to explore their genetic relationships with Ceres. Methods: We obtained visible spectra of these 14 asteroids using the OSIRIS spectrograph at the 10.4 m Gran Telescopio Canarias(GTC). We computed spectral slopes in two different wavelength ranges, from 0.49 to 0.80μm and from 0.80 to 0.92μm, to compare the values obtained with those on Ceres' surface previously computed using the Visible and Infrared Spectrometer (VIR) instrument onboard the NASA Dawn spacecraft. We also calculated the spectral slopes in the same range for ground-based observations of Cerescollected from the literature. Results: We present the visible spectra and the taxonomy of 14 observed asteroids. We found that only two of the asteroids are spectrally compatible with Ceres' surface. Further analysis of those two asteroids indicates that they are spectrally young and thus less likely to be members of the Ceres family. Conclusions: All in all, our results indicate that most of the 14 observed asteroids are not likely to belong to a Ceres collisional family. Despite two of them being spectrally compatible with the young surface of Ceres, further evaluation is needed to confirm or reject their origin from Ceres.

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arXiv2020

Spectral characterisation of 14 V-type candidate asteroids from the MOVIS catalogue

Most of the currently known basaltic (V-type) asteroids are believed to be past or present members of the Vesta dynamical family. The rising discoveries of V-type asteroids that are not dynamically linked to the Vesta family suggest that a number of major basaltic bodies may have been present during the early stages of the solar system. In this work, we aim to provide a spectral analysis of 14 V-type candidates of various dynamical types, selected from the Moving Objects from VISTA Survey (MOVIS) catalogue. The computed visible and near-infrared (NIR) spectral parameters are used to investigate evidence of space-weathering or mineralogical differences from the expected basaltic composition. Based on the analysis of their visible spectra, we confirm 11 new V-type asteroids: six low-i asteroids - (3188) Jekabsons, (3331) Kvistaberg, (4693) Drummond, (7223) Dolgorukij, (9007) James Bond, and (29733) 1999 BA4; along with four inner-other asteroids - (5524) Lecacheux, (19983) 1990 DW, (51742) 2001 KE$_{55}$, and (90023) 2003 BD$_{13}$; as well as one fugitive - (2275) Cuitlahuac. Additionally, we analysed three peculiar outer main belt candidates based on their visible + NIR spectra. We confirm the diogenite-like composition of (2452) Lyot. The spectrum of asteroid (7302) is inconsistent with a basaltic composition and likely reflects an S-type body. The spectrum of (14390) 1990 QP$_{10}$ shows unique features that suggest a peculiar, unclassified composition. Overall, our results demonstrate the efficiency of the MOVIS catalogue in identifying V-type objects, with a success rate of over 85\%. The identification of V-types in the inner main-belt is more likely due to the presence of the Vesta family and other nearby asteroids that had escaped from the family. In the middle and outer main belt, where the amount of data is more limited, the proportion of false positives increases.

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arXiv2019

ASIME 2018 White Paper. In-Space Utilisation of Asteroids: Asteroid Composition -- Answers to Questions from the Asteroid Miners

In keeping with the Luxembourg government's initiative to support the future use of space resources, ASIME 2018 was held in Belval, Luxembourg on April 16-17, 2018. The goal of ASIME 2018: Asteroid Intersections with Mine Engineering, was to focus on asteroid composition for advancing the asteroid in-space resource utilisation domain. What do we know about asteroid composition from remote-sensing observations? What are the potential caveats in the interpretation of Earth-based spectral observations? What are the next steps to improve our knowledge on asteroid composition by means of ground-based and space-based observations and asteroid rendez-vous and sample return missions? How can asteroid mining companies use this knowledge? ASIME 2018 was a two-day workshop of almost 70 scientists and engineers in the context of the engineering needs of space missions with in-space asteroid utilisation. The 21 Questions from the asteroid mining companies were sorted into the four asteroid science themes: 1) Potential Targets, 2) Asteroid-Meteorite Links, 3) In-Situ Measurements and 4) Laboratory Measurements. The Answers to those Questions were provided by the scientists with their conference presentations and collected by A. Graps or edited directly into an open-access collaborative Google document or inserted by A. Graps using additional reference materials. During the ASIME 2018, first day and second day Wrap-Ups, the answers to the questions were discussed further. New readers to the asteroid mining topic may find the Conversation boxes and the Mission Design discussions especially interesting.

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arXiv2019

Spectroscopic and dynamical properties of comet C/2018 F4, likely a true average former member of the Oort cloud

The population of comets hosted by the Oort cloud is heterogeneous. Most studies in this area focused on highly active objects, those with small perihelion distances or examples of objects with peculiar physical properties and/or unusual chemical compositions. This may have produced a biased sample of Oort cloud comets in which the most common objects may be rare, particularly those with perihelia well beyond the orbit of the Earth. Within this context, the known Oort cloud comets may not be representative of the full sample. Here, we study the spectral properties in the visible region and the cometary activity of Comet C/2018 F4 (PANSTARRS). We also explore its orbital evolution with the aim of understanding its origin within the context of known minor bodies moving along nearly parabolic or hyperbolic paths. We present observations obtained with the 10.4 m Gran Telescopio Canarias (GTC), derive the spectral class and visible slope of C/2018 F4 and characterise its level of cometary activity. Direct N-body simulations are carried out to explore its orbital evolution. The absolute magnitude of C/2018 F4 is Hr=13.62+/-0.04. Assuming a pV=0.04 its diameter is D<10.4 km. The object presents a conspicuous coma, with a level of activity comparable to those of other comets observed at similar heliocentric distances. Comet C/2018 F4 has a visible spectrum consistent with that of an X-type asteroid, and has a spectral slope S'=4.0+/-1.0 %/1000Åand no evidence of hydration. The spectrum matches those of well-studied primitive asteroids and comets. The analysis of its dynamical evolution prior to discovery suggests that C/2018 F4 is not of extrasolar origin. Although the present-day heliocentric orbit of C/2018 F4 is slightly hyperbolic, its observational properties and past orbital evolution are consistent with those of a dynamically old comet with an origin in the Oort cloud.

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arXiv2018

Compositional Diversity Among Primitive Asteroids

Spectroscopic observations from the ultraviolet to the mid-infrared have revealed new and diagnostic differences among primitive asteroids. We review the spectral characteristics of these asteroids and their inferred compositional and physical properties. Primitive asteroids throughout the belt show carbon-rich compounds, varying degrees of aqueous alteration and even surface ice; recent observations provide significant new constraints on composition, thermal inertia, and other surface properties. New mid-infrared connections between primitive asteroids and interplanetary dust particles indicate that the latter sample a larger fraction of main belt asteroids than meteorites. Links with the composition of comets are consistent with a proposed continuum between primitive asteroids and comets. Two sample-return missions, OSIRIS-REx and Hayabusa 2, will visit primitive near-Earth asteroids (NEAs). Most spacecraft-accessible NEAs originate in the inner asteroid belt, which contains several primitive asteroid families and a background of primitive asteroids outside these families. Initial results from these families offer a tantalizing preview of the properties expected in the NEAs they produce. So far, primitive asteroids in the inner belt fall into two spectral groups. The first group includes the Polana-Eulalia families, which show considerable spectral homogeneity in spite of their dynamical and collisional complexity. In contrast, the Erigone and Sulamitis families are spectrally diverse and most of their members show clear 0.7 microns hydration features. The two sample-return targets (101955) Bennu and (162173) Ryugu, most likely originated in the Polana family.

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