Françoise Roques
A5054166242- Astro and Planetary Science
- Planetary Science and Exploration
- Stellar, planetary, and galactic studies
- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Isotope Analysis in Ecology
- Space Exploration and Technology
- Atmospheric Ozone and Climate
- Astronomical Observations and Instrumentation
- Geomagnetism and Paleomagnetism Studies
- Gamma-ray bursts and supernovae
- Space Science and Extraterrestrial Life
- History and Developments in Astronomy
- Geology and Paleoclimatology Research
- Scientific Research and Discoveries
- Geological and Geochemical Analysis
- Adaptive optics and wavefront sensing
- Historical Astronomy and Related Studies
- Advanced Optical Sensing Technologies
- Global Energy and Sustainability Research
- CCD and CMOS Imaging Sensors
- Maritime and Coastal Archaeology
- Space exploration and regulation
- Laser-induced spectroscopy and plasma
Université Paris Cité
2015-2025
Laboratoire d’études spatiales et d’instrumentation en astrophysique
2016-2025
Sorbonne Paris Cité
2017-2025
Observatoire de Paris
2013-2025
Sorbonne Université
2015-2025
Centre National de la Recherche Scientifique
2013-2025
Délégation Paris 7
2011-2025
Université Paris Sciences et Lettres
1993-2025
Université de Versailles Saint-Quentin-en-Yvelines
2011-2023
Janssen (France)
2004-2021
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...
In recent years, stellar occultations have been a powerful tool in the study of small bodies solar system (e.g., rings, satellites, asteroids). Diffraction effects to be taken into account order interpret light curves. The authors develop theoretical models, from Fresnel-Kirchhoff diffraction theory, by semitransparent strips and opaque elliptical disks, give explicit methods for computing them. They discuss implications during use their own models distinguish dips that are artifacts those...
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...
We report the observation of two stellar occultations by Titan on 14 November 2003, using stations in Indian Ocean, southern Africa, Spain, and northern Americas. These probed altitudes between ∼550 250 km (∼1 to μ bar) Titan's upper stratosphere. The light curves reveal a sharp inversion layer near 515 ± 6 altitude (1.5 bar pressure level), where temperature increases 15 K only km. This is close an observed fourteen months later Huygens HASI instrument during entry probe atmosphere January...
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...
We report here the first detection of hectometer-size objects by method serendipitous stellar occultation. This consists recording diffraction shadow created when an object crosses observer's line sight and occults disk a background star. One our detections is most consistent with between Saturn Uranus. The two other patterns detected are caused Kuiper Belt beyond 100 AU from Sun hence farthest known in solar system. These show that much more extended than previously believed outer part...
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...
The Uranian rings were discovered serendipitously on 10 March 1977 during a stellar occultation (Elliot et al., 1977a; Millis 1977), and rich set of subsequent Earth-based occultations revealed that these narrow sharp-edged eccentric inclined, precessing under the gravitational influence oblate central planet. Considerable progress has been made in understanding observed characteristics sharp edges (Nicholson 2018) their associated dynamics (Longaretti, 2018), but ever since discovery, have...