相关论文: Spin state and moment of inertia of Venus
The alignment of Saturn's magnetic pole with its rotation axis precludes the use of magnetic field measurements to determine its rotation period. The period was previously determined from radio measurements by the Voyager spacecraft to be…
Both Uranus and Neptune are thought to have strong zonal winds with velocities of several hundred meters per second. These wind velocities, however, assume solid-body rotation periods based on Voyager 2 measurements of periodic variations…
Saturn's C ring contains multiple structures that appear to be density waves driven by time-variable anomalies in the planet's gravitational field. Semi-empirical extensions of density wave theory enable the observed wave properties to be…
In determining Mercury's core structure from its rotational properties, the value of the normalized moment of inertia, $C/MR^2$, from the location of Cassini 1 is crucial. If Mercury's spin axis occupies Cassini state 1, its position…
Five Venus missions are under development to study the planet in the next decade, with both NASA's VERITAS and ESA's EnVision featuring a geophysical investigation among their objectives. Their radar and gravity experiments will determine…
Venus' mass and radius are similar to those of Earth. However, dissimilarities in atmospheric properties, geophysical activity and magnetic field generation could hint towards significant differences in the chemical composition and interior…
The atmosphere of a transiting planet shields the stellar radiation providing us with a powerful method to estimate its size and density. In particular, because of their high ionization energy, atoms with high atomic number (Z) absorb…
Knowledge of Saturn's axial moment of inertia can provide valuable information on its internal structure. We suggest that Saturn's angular momentum may be determined by the Solstice Mission (Cassini XXM) by measuring Saturn's pole…
The atmospheric circulation in Venus is well known to exhibit strong super-rotation. However, the atmospheric mechanisms responsible for the formation of this super-rotation are still not fully understood. In this work, we developed a new…
Measuring Venus' atmospheric circulation at different altitudes is important for understanding its complex dynamics, in particular the mechanisms driving the super-rotation. Observationally, Doppler imaging spectroscopy is in principle be…
We investigate Venus Express (VEX) observations of magnetic field fluctuations performed systematically in the solar wind at 0.72 Astronomical Units (AU), between 2007 and 2009, during the deep minimum of the solar cycle 24. The Power…
We present an analysis of 1524 spectra of Vega spanning 10 years, in which we search for periodic radial velocity variations. A signal with a periodicity of 0.676 days and a semi-amplitude of ~10 m/s is consistent with the rotation period…
It is known since the seminal study of Laskar (1989) that the inner planetary system is chaotic with respect to its orbits and even escapes are not impossible, although in time scales of billions of years. The aim of this investigation is…
We obtained two astronomical values, the Earth-Venus distance and Venus diameter, by means of a geometrical treatment of photos taken of Venus transit in June of 2012. Here we presented the static and translational modelsthat were…
Planetary rotation rate is a key parameter in determining atmospheric circulation and hence the spatial pattern of clouds. Since clouds can exert a dominant control on planetary radiation balance, rotation rate could be critical for…
We report Venus image observations around the two maximum elongations of the planet at June and October 2015. From these images we describe the global atmospheric dynamics and cloud morphology in the planet before the arrival of JAXA…
The bright star $\lambda$ Ser hosts a hot Neptune with a minimum mass of 13.6 $M_\oplus$ and a 15.5 day orbit. It also appears to be a solar analog, with a mean rotation period of 25.8 days and surface differential rotation very similar to…
Minor planet 2002 VE68 was identified as a quasi-satellite of Venus shortly after its discovery. At that time its data-arc span was only 24 days, now it is 2,947 days. Here we revisit the topic of the dynamical status of this remarkable…
The competition between the torques induced by solid and thermal tides drives the rotational dynamics of Venus-like planets and super-Earths orbiting in the habitable zone of low-mass stars. The tidal responses of the atmosphere and…
The variation of the solar diameter in time and in position angle has implications in astrophysics and in general relativity, as the long series of studies attest. The Transits of Venus in 2004 and 2012 have been carefully studied because…