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An equatorial thermal wind equation: Applications to Jupiter
Wong, Michael H.; Tollefson, Joshua; Marcus, Philip S. +1 more
To relate the vertical wind shear to horizontal temperature gradients at and near the equator, we derive an "Equatorial Thermal Wind Equation" (EQTWE) using a minimum set of assumptions that are easily satisfied for the atmospheres of all the giant planets and Earth. Similar to the textbook Thermal Wind Equation (TWE), the EQTWE requires a small R…
Ultraviolet observation of Enceladus' plume in transit across Saturn, compared to Europa
Hansen, C. J.; Hendrix, A. R.; Esposito, L. W.
Saturn's moon Enceladus is known to have a water vapor plume erupting from fissures across its south polar region. The plume was detectable in an observation of Enceladus transiting Saturn by Cassini's Ultraviolet Imaging Spectrograph (UVIS), but only at 1216 Å (Lyman alpha). Jupiter's moon Europa also may have multiple water vapor plumes, detecte…
First measurements of Jupiter's zonal winds with visible imaging spectroscopy
Sato, Bun'ei; Rivet, Jean-Pierre; Guillot, Tristan +12 more
We present the first measurements of Jupiter's wind profile ever obtained with Doppler velocity measurements in the visible. Hitherto, knowledge about atmospheric dynamics has been obtained with cloud-tracking techniques, which consist of tracking visible features from images taken at different dates. However, cloud tracking indicates the motion o…
The color and binarity of (486958) 2014 MU69 and other long-range New Horizons Kuiper Belt targets
Stern, S. A.; Kavelaars, J. J.; Weaver, H. A. +9 more
The Hubble Space Telescope (HST) measured the colors of eight Kuiper Belt Objects (KBOs) that will be observed by the New Horizons spacecraft including its 2019 close fly-by target the Cold Classical KBO (486958) 2014 MU69. We find that the photometric colors of all eight objects are red, typical of the Cold Classical dynamical populati…
A common origin for dynamically associated near-Earth asteroid pairs
Wasserman, Lawrence H.; Hora, Joseph L.; Thirouin, Audrey +19 more
Though pairs of dynamically associated asteroids in the Main Belt have been identified and studied for over a decade, very few pair systems have been identified in the near-Earth asteroid population. We present data and analysis that supports the existence of two genetically related pairs in near-Earth space. The members of the individual systems,…
Equatorial Kelvin-like waves on slowly rotating and/or small-sized spheres: Application to Venus and Titan
Yamamoto, Masaru
Equatorial Kelvin waves, which have been observed in planetary fluids, produce superrotation and climatological variability. Although the meridional flow component is zero on Earth's beta-plane in the absence of background basic flow, it cannot be neglected on spheres in some planetary fluids when the Lamb parameter is small. For a vertically prop…
Haumea's thermal emission revisited in the light of the occultation results
Fornasier, S.; Lellouch, E.; Marton, G. +9 more
A recent multi-chord occultation measurement of the dwarf planet (136108) Haumea (Ortiz et al., 2017) revealed an elongated shape with the longest axis comparable to Pluto's mean diameter. The chords also indicate a ring around Haumea's equatorial plane, where its largest moon, Hi'iaka, is also located. The Haumea occultation size estimate (size o…
A laboratory-based dielectric model for the radar sounding of the martian subsurface
Thomas, Nicolas; Becerra, Patricio; Pommerol, Antoine +2 more
For the last decade, the SHARAD radar on board NASA's Mars Reconnaissance Orbiter, and the MARSIS radar on board ESA's Mars Express, have sounded the surface and subsurface of Mars from orbit to search for and characterise water ice reservoirs. When associated with dielectric models, the regolith composition (in terms of dust, ice and voids) of th…
The mean rotation rate of Venus from 29 years of Earth-based radar observations
Campbell, Donald B.; Margot, Jean-Luc; Nolan, Michael C. +7 more
We measured the length of the Venus sidereal day (LOD) from Earth-based radar observations collected from 1988 to 2017, using offsets in surface feature longitudes from a prediction based on a 243.0185d period derived from analysis of Magellan mission images over a 487-day interval. We derive a mean LOD over 29 years of 243.0212 ± 0.0006d. Our res…
A spectral synergy method to retrieve martian water vapor column-abundance and vertical distribution applied to Mars Express SPICAM and PFS nadir measurements
Montmessin, F.; Ferron, S.
Up to now, all attempts to retrieve martian water vapor from nadir observations have focused their analysis on a single spectral domain and comparison between the results of various experiments showed the difficulty to reconcile the water vapor datasets together. Inspired by a methodology recently developed for the analysis of Earth observations, …