A. R. Gomes-Júnior
A5091907511- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Planetary Science and Exploration
- Atmospheric Ozone and Climate
- Astronomical Observations and Instrumentation
- Isotope Analysis in Ecology
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Solar and Space Plasma Dynamics
- Space Exploration and Technology
- Geology and Paleoclimatology Research
- Astronomy and Astrophysical Research
- Geological and Geochemical Analysis
- Geomagnetism and Paleomagnetism Studies
- Mathematics and Applications
- Ionosphere and magnetosphere dynamics
- Astrophysical Phenomena and Observations
- Child Nutrition and Feeding Issues
- Autism Spectrum Disorder Research
- Geometry and complex manifolds
- Geometric and Algebraic Topology
- Astronomical and nuclear sciences
- Spacecraft Design and Technology
- Scientific Research and Discoveries
- History and Theory of Mathematics
Laboratório Interinstitucional de e-Astronomia
2018-2025
Universidade Federal de Uberlândia
2022-2025
Federal University of São João del-Rei
2024
Universidade Estadual Paulista (Unesp)
2018-2024
Universidade de São Paulo
2020-2023
Valongo Observatory
2011-2022
Universidade Federal do Rio de Janeiro
2013-2022
National Observatory
2019
Abstract The physical and orbital parameters of trans-Neptunian objects provide valuable information about the solar system’s formation evolution. In particular, characterization binaries provides insights into mechanisms that may be playing a role at such large distances from Sun. Studies show two distinct populations, (38628) Huya occupies an intermediate position between unequal-sized those with components roughly equal sizes. this work, we predicted observed three stellar occultation...
Jupiter Trojans preserve primitive formation characteristics owing to their collisionless, stable orbits. Determination of shapes and size-frequency distribution helps constrain the collisional evolution parent population, which also originated Kuiper Belt. We started a programme find precise sizes/shapes for Trojans, combining stellar occultations Database Asteroid Models from Inversion Techniques (DAMIT) three-dimensional shape models. report results Diomedes, by fitting its unit...
ABSTRACT We present results from a multi-chord Pluto stellar occultation observed on 2015 June 29 New Zealand and Australia. This occurred only two weeks before the NASA Horizons flyby of system serves as useful comparison between ground-based space results. find that Pluto's atmosphere is still expanding, with significant pressure increase 5 ± 2% since 2013 factor almost three 1988. trend rules out, today, an atmospheric collapse associated recession Sun. A central flash, rare occurrence,...
Quaoar is a classical Trans-Neptunian Object (TNO) with an area equivalent diameter of 1,100 km and orbital semi-major axis 43.3 astronomical units. Based on stellar occultations observed between 2018 2021, inhomogeneous ring (Q1R, Quaoar's first ring) was detected around this body. Aims. A new occultation by August 9th, 2022 aiming to improve shape models the physical parameters Q1R while searching for additional material Methods. The provided nine effective chords across Quaoar, pinning...
In 2013, a stellar occultation revealed the presence of ring system around Centaur Chariklo, marking first discovery such feature on small body. Subsequent observations indicated that main exhibits not only radial density variations but also changes in width depending longitude. this study, we propose method to determine longitude (within an inertial reference frame) and orbital radius each point detected during occultations. addition, provide descriptive analysis ring’s identify combination...
We were able to accurately predict the shadow path and successfully observe an occultation of a bright star by Chiron on December 15, 2022. The Kottamia Astronomical Observatory in Egypt did not detect solid body, but we found three extinction features light curve that had symmetrical counterparts with respect central time occultation. One is broad shallow, whereas other two are sharper, maximum ∼25% at achieved spatial resolution 19 km per data point. From Wise Israel, detected caused main...
We analyze two multi-chord stellar occultations by Pluto observed on July 18th, 2012 and May 4th, 2013, monitored respectively from five six sites. They provide a total of fifteen light-curves, twelve them being used for simultaneous fit that uses unique temperature profile, assuming clear (no-haze) pure N_2 atmosphere, but allowing possible pressure variation between the dates. find solution fits satisfactorily (i.e. within noise level) all providing atmospheric constraints ~1,190 km...
Two narrow and dense rings (called C1R C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned observations of several occultations by Chariklo's system in order to better characterize physical properties ring main body. Here, use 12 successful occulations between 2014 2016. They provide profiles (physical width, opacity, edge structure) constraints radii pole position. Our new are currently...
Combining stellar occultation observations probing Pluto's atmosphere from 1988 to 2013, and models of energy balance between surface atmosphere, we find the preferred are consistent with Pluto retaining a collisional throughout its 248-year orbit. The results show an increasing atmospheric pressure time in current epoch, trend present only high thermal inertia permanent N2 ice cap at north rotational pole.
The stellar occultation technique provides competitive accuracy in determining the sizes, shapes, astrometry, etc., of occulting body, comparable to in-situ observations by spacecraft. With increase number known Solar System objects expected from LSST, highly precise astrometric catalogues, such as Gaia, and improvement ephemerides, occultations will become more common with a higher chords each observation. In context Big Data era, we developed SORA, an open-source python library reduce...
The physical and orbital parameters of Trans-Neptunian Objects (TNOs) provide valuable information about the Solar System's formation evolution. In particular, characterization binaries provides insights into mechanisms that may be playing a role at such large distances from Sun. Studies show two distinct populations, (38628) Huya occupies an intermediate position between unequal-size those with components roughly equal sizes. this work, we predicted observed three stellar occultation events...
Context. The prediction of stellar occultations by trans-Neptunian objects (TNOs) and Centaurs is a difficult challenge that requires accuracy both in the occulted star position object ephemeris. Until now, most used method prediction, involving dozens TNOs/Centaurs, has been to consider constant offset for right ascension declination with respect reference ephemeris, usually latest public version. This determined as difference between recent observations TNO/Centaur can be successfully...
We use data from five stellar occultations observed between 2013 and 2016 to constrain Chariklo's size shape, the ring reflectivity. consider four possible models for Chariklo (sphere, Maclaurin spheroid, tri-axial ellipsoid Jacobi ellipsoid) we a Bayesian approach estimate corresponding parameters. The spherical model has radius $R=129\pm3$ km. equatorial polar radii $a=b=143^{+3}_{-6}$ km $c=96^{+14}_{-4}$ km, respectively, with density $970^{+300}_{-180}$ kg m$^{-3}$. ellipsoidal semiaxes...
Context. Pluto's tenuous nitrogen (N2) atmosphere undergoes strong seasonal effects due to high obliquity and orbital eccentricity, has been recently (July 2015) observed by the New Horizons spacecraft. Goals are (i) construct a well calibrated record of evolution surface pressure on Pluto (ii) constrain structure lower using central flash in 2015. Method: eleven stellar occultations between 2002 2016 used retrieve atmospheric profiles (density, pressure, temperature) $\sim$5 km $\sim$380...
After the discovery of rings around largest known Centaur object, (10199) Chariklo, we carried out observation campaigns stellar occultations produced by second-largest (2060) Chiron, to better characterize its physical properties and presence material on surroundings. We predicted successfully observed two Chiron. These observations were used constrain size shape fitting elliptical limbs with equivalent surface radii in agreement radiometric measurements. Constraints Chiron are reported for...
We present results derived from the first multi-chord stellar occultation by trans-Neptunian object (229762) 2007 UK$_{126}$, observed on 2014 November 15. The event was Research and Education Collaborative Occultation Network (RECON) project International Timing Association (IOTA) collaborators throughout United States. Use of two different data analysis methods obtain a satisfactory fit to seven chords, yelding an elliptical chords with equatorial radius $R=338_{-10} ^{+15}$ km equivalent...
A stellar occultation by Neptune's main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves this event, 42 of which yielded a central flash detection. aimed at constraining Triton's atmospheric structure seasonal variations its pressure since Voyager 2 epoch (1989). also shape lower atmosphere analysis. used Abel inversions direct ray-tracing code to provide density, pressure, temperature profiles in altitude range $\sim$8 km...
Context. In about 2000, the south pole of Triton experienced an extreme summer solstice that occurs every ∼650 years, when subsolar latitude reached 50°S. Bracketing this epoch, a few occultations probed atmosphere in 1989, 1995, 1997, 2008, and 2017. A recent ground-based stellar occultation observed on 6 October 2022 provides new measurement atmospheric pressure Triton. This is presented here. Aims. The goal to constrain volatile transport models (VTMs) atmosphere. basically vapor...
Context. The physical characterization of trans-Neptunian objects is essential for improving our understanding the formation and evolution Solar System. Stellar occultation a ground-based technique that can be successfully used to determine some TNOs’ fundamental properties with high precision, such as size shape. Aims. This work aimed at constraining size, shape, geometric albedo dwarf planet candidate (307261) 2002 MS 4 through analysis nine stellar events. Using multichord detection, we...
The irregular satellites of the giant planets are believed to have been captured during evolution solar system. Knowing their physical parameters, such as size, density, and albedo is important for constraining where they came from how were captured. best way obtain these parameters observations in situ by spacecrafts or stellar occultations objects. Both techniques demand that orbits well known. We aimed good astrometric positions improve ephemeris. identified reduced several three...