Publications by authors named "Geronimo L Villanueva"
Article Synopsis
- - Charon, Pluto's largest moon, has been studied for its composition and changes caused by radiation, but previous spectral data only covered wavelengths below 2.5 μm, leaving some questions unanswered.
- - Recent observations using JWST have detected carbon dioxide (CO) and hydrogen peroxide (HO) on Charon's northern hemisphere, adding to its known chemical components like water ice and ammonia.
- - The presence of HO suggests active processes affecting the water ice surface, while spectral analysis indicates that CO is mainly found in crystalline form, likely originating from subsurface sources and other processes involving hydrocarbons and solar interactions.
Main-belt comets are small Solar System bodies located in the asteroid belt that repeatedly exhibit comet-like activity (that is, dust comae or tails) during their perihelion passages, strongly indicating ice sublimation. Although the existence of main-belt comets implies the presence of extant water ice in the asteroid belt, no gas has been detected around these objects despite intense scrutiny with the world's largest telescopes. Here we present James Webb Space Telescope observations that clearly show that main-belt comet 238P/Read has a coma of water vapour, but lacks a significant CO gas coma.
View Article and Find Full Text PDFIsotopic ratios and, in particular, the water D/H ratio are powerful tracers of the evolution and transport of water on Mars. From measurements performed with ExoMars/NOMAD, we observe marked and rapid variability of the D/H along altitude on Mars and across the whole planet. The observations (from April 2018 to April 2019) sample a broad range of events on Mars, including a global dust storm, the evolution of water released from the southern polar cap during southern summer, the equinox phases, and a short but intense regional dust storm.
View Article and Find Full Text PDFLiving systems produce more than 90% of Earth's atmospheric methane; the balance is of geochemical origin. On Mars, methane could be a signature of either origin. Using high-dispersion infrared spectrometers at three ground-based telescopes, we measured methane and water vapor simultaneously on Mars over several longitude intervals in northern early and late summer in 2003 and near the vernal equinox in 2006.
View Article and Find Full Text PDFWe quantified eight parent volatiles (H2O, C2H6, HCN, CO, CH3OH, H2CO, C2H2, and CH4) in the Jupiter-family comet Tempel 1 using high-dispersion infrared spectroscopy in the wavelength range 2.8 to 5.0 micrometers.
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