Search Publications
Spectral states evolution of 4U 1728-34 observed by INTEGRAL and RXTE: non-thermal component detection
Belloni, T.; Ubertini, P.; Bazzano, A. +2 more
We report results of a one-year monitoring of the low-mass X-ray binary (LMXB) source (atoll type) 4U 1728-34 with INTEGRAL and RXTE. Three time intervals were covered by INTEGRAL, during which the source showed strong spectral evolution. We studied the broad-band X-ray spectra in detail by fitting several models in the different sections of the h…
Saturn’s Curiously Corrugated C Ring
Hedman, M. M.; Burns, J. A.; Porco, C. C. +2 more
In August 2009 the Sun illuminated Saturn’s rings from almost exactly edge-on, revealing a subtle corrugation that extends across the entire C ring. This corrugation’s amplitude is 2 to 20 meters and its wavelength is 30 to 80 kilometers. Radial trends in the corrugation’s wavelength indicate that this structure—like a similar corrugation previous…
A Search for Water Vaporization on Ceres
Carry, B.; Mousis, O.; Jehin, E. +5 more
There are hints that the dwarf planet (1) Ceres may contain a large amount of water ice. Some models and previous observations suggest that ice could be close enough to the surface to create a flux of water outward through the regolith. This work aims to confirm a previous detection of OH emission off the northern limb of Ceres with the Internatio…
The Dark Side of QSO Formation at High Redshifts
Trenti, Michele; Hoffman, Yehuda; Shlosman, Isaac +1 more
Observed high-redshift QSOs, at z ~ 6, may reside in massive dark matter (DM) halos of more than 1012 M sun and are thus expected to be surrounded by overdense regions. In a series of 10 constrained simulations, we have tested the environment of such QSOs. The usage of constrained realizations has enabled us to address the is…
The distribution of the ring current: Cluster observations
Woodfield, E. E.; Lockwood, M.; Dunlop, M. W. +9 more
Extending previous studies, a full-circle investigation of the ring current has been made using Cluster 4-spacecraft observations near perigee, at times when the Cluster array had relatively small separations and nearly regular tetrahedral configurations, and when the Dst index was greater than -30 nT (non-storm conditions). These observations res…
Volatiles in the atmosphere of Mars: The effects of volcanism and escape constrained by isotopic data
Gillmann, Cédric; Lognonné, Philippe; Moreira, Manuel
We study the long term evolution of the conditions on the surface of Mars through the modeling of the effects of volcanic degassing and atmospheric non-thermal escape during the last four billion yr. We propose to use the recent advances due to observation and modeling to constrain possible evolutions of the atmosphere of Mars with the help of iso…
67P/Churyumov-Gerasimenko at large heliocentric distance
Agarwal, J.; Tubiana, C.; Ortiz, J. L. +3 more
Aims: The Jupiter family comet (JFC) 67P/Churyumov-Gerasimenko (67P/C-G) is the target of ESA's ROSETTA mission. Observational campaigns and theoretical investigations were performed to characterise 67P/C-G in terms of nucleus properties (e.g. size, surface colours, rotational period), gas and dust production, and plasma environment in prepar…
The Star Formation History of Isolated Dwarf UGC 4879
Held, Enrico V.; Chiboucas, Kristin; Tully, R. Brent +3 more
Recent observations of UGC 4879 with the Advanced Camera for Surveys on the Hubble Space Telescope confirm that it is a nearby isolated dwarf irregular galaxy. We measure a distance of 1.36 ± 0.03 Mpc using the tip of the red giant branch method. This distance puts UGC 4879 beyond the radius of first turnaround of the Local Group and ~700 kpc from…
The torsional oscillation and the new solar cycle
Thompson, M. J.; Howe, R.; Komm, R. +5 more
We present updated observations of the pattern of migrating solar zonal flows known as the torsional oscillation, covering 15 years of helioseismic measurements with GONG and MDI and 30 years of surface Doppler observations from Mount Wilson. We compare the behavior of the flows during the extended solar minimum following Cycle 23 with that in ear…
Simulation of Io's auroral emission: Constraints on the atmosphere in eclipse
Saur, Joachim; Roth, Lorenz; Strobel, Darrell F. +2 more
We study the morphology of Io's aurora by comparing simulation results of a three-dimensional (3D) two-fluid plasma model to observations by the high-resolution Long-Range Reconnaissance Imager (LORRI) on-board the New Horizons spacecraft and by the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS). In 2007, Io's auroral emission in ecl…