R. Duffárd
A5049403447- Astro and Planetary Science
- Planetary Science and Exploration
- Stellar, planetary, and galactic studies
- Isotope Analysis in Ecology
- Astrophysics and Star Formation Studies
- Space Exploration and Technology
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Solar and Space Plasma Dynamics
- Geology and Paleoclimatology Research
- Atmospheric Ozone and Climate
- Geomagnetism and Paleomagnetism Studies
- Geological and Geochemical Analysis
- High-pressure geophysics and materials
- Space Satellite Systems and Control
- Adaptive optics and wavefront sensing
- Geophysics and Gravity Measurements
- Photocathodes and Microchannel Plates
- solar cell performance optimization
- Spacecraft and Cryogenic Technologies
- Astronomical and nuclear sciences
- Nuclear Physics and Applications
- History and Developments in Astronomy
- Historical Astronomy and Related Studies
Instituto de Astrofísica de Andalucía
2015-2024
Consejo Superior de Investigaciones Científicas
2007-2023
McDonald's (United States)
2023
Adıyaman University
2023
Odlewnie Polskie (Poland)
2023
Unidades Centrales Científico-Técnicas
2020
Hudson Institute
2018-2019
John Wiley & Sons (United States)
2018-2019
Jackson State University
2018-2019
Curtin University
2018-2019
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...
<i>Context. <i/>The goal of the <i>Herschel<i/> open time programme "<i>TNOs are Cool!<i/>" is to derive physical and thermal properties for a large sample Centaurs, trans-Neptunian objects (TNOs), including resonant, classical, detached scattered disk objects.<i>Aims. <i/>Based on observations two targets we tried (i) optimise SPIRE observing technique faint (close background confusion noise), slowly moving targets; (ii) test different model techniques; (iii) determine radiometric diameter...
Transneptunian objects (TNOs) are bodies populating the Kuiper Belt and they believed to retain most pristine least altered material of solar system. The Herschel Open Time Key Program entitled "TNOs Cool: A survey trans-Neptunian region" has been awarded 373 h investigate albedo, size distribution thermal properties TNOs Centaurs. Here we focus on brightest targets observed by both PACS SPIRE multiband photometers: dwarf planet Haumea, six (Huya, Orcus, Quaoar, Salacia, 2002 UX25, TC302),...
We analyze albedo data obtained using the Herschel Space Observatory that reveal existence of two distinct types surface among midsized trans-Neptunian objects. A color–albedo diagram shows large clusters objects, one redder and higher another darker more neutrally colored. Crucially, all objects in our sample located dynamically stable orbits within classical Kuiper Belt region beyond are confined to bright red group, implying a compositional link. Those believed have formed further from...
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,...
We present results derived from the first multi-chord stellar occultations by transneptunian object (50000) Quaoar, observed on 2011 May 4 and 2012 February 17, a single-chord occultation October 15. If timing of five chords obtained in were correct, then Quaoar would possess topographic features (crater or mountain) that be too large for body this mass. An alternative model consists applying time shifts to some account possible errors. Satisfactory elliptical fits are possible, yielding an...
We propose that several short duration events observed in past stellar occultations by Chiron were produced rings material. From a reanalysis of the occultation data literature we determined two possible orientations pole Chiron's rings, with ecliptic coordinates l=(352+/-10) deg, b=(37+/-10) deg or l=(144+/-10) b=(24+/-10) . The mean radius is (324 +/- 10) km. One can use rotational lightcurve amplitude at different epochs to distinguish between solutions for pole. Both imply lower 2013...
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 present results of 6 years observations, reduced and analyzed with the same tools in a systematic way. report completely new data for 15 objects, 5 objects we analysis previously published plus additional 9 already published. Lightcurves, possible rotation periods photometric amplitudes are reported all them. The variability is smaller than thought: mean amplitude our sample 0.1mag only around 15% has larger 0.15mag. thought seems to be bias previous observations. find very weak trend...
Over one thousand objects have so far been discovered orbiting beyond Neptune. These trans-Neptunian (TNOs) represent the primitive remnants of planetesimal disk from which planets formed and are perhaps analogous to unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical physical properties these bodies provide unique important constraints on formation evolution models Solar System. While architecture this region (also known as Kuiper Belt) is...
We present Herschel PACS photometry of 18 Plutinos and determine sizes albedos for these objects using thermal modeling. analyze our results correlations, draw conclusions on the Plutino size distribution, compare to earlier results. Flux densities are derived from mini scan-maps specialized data reduction methods. In order improve quality results, we combine with existing Spitzer MIPS where possible, refine absolute magnitudes targets. The physical characterization sample is done a model....
Centaurs are the transitional population between trans-Neptunian objects (TNOs) and Jupiter-family comets. For this reason it is possible to access smaller ones, which more difficult do with TNO population. The goal of work characterize a set 16 in terms their size, albedo, thermal properties. We study correlations, for extended sample obtained from literature, diameter, orbital parameters, spectral slopes. performed three-band photometric observations using Herschel-PACS used consistent...
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...
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...