Search Publications
Exoplanet HD 209458b (Osiris): Evaporation Strengthened
Lecavelier des Etangs, A.; Ferlet, R.; Vidal-Madjar, A. +4 more
Following reanalysis of Hubble Space Telescope observations of primary transits of the extrasolar planet HD 209458b at Lyα, Ben-Jaffel claims that no sign of evaporation is observed. Here we show that, in fact, this new analysis is consistent with the one of Vidal-Madjar and coworkers, and supports the detection of evaporation. The apparent disagr…
Abundance of minerals in the phyllosilicate-rich units on Mars
Mangold, N.; Bibring, J. -P.; Gondet, B. +4 more
Context: Phyllosilicates were definitely identified on Mars by the OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) instrument onboard the Mars Express spacecraft. The identification, characterization, and mapping of deposits of these minerals hold clues to the potential past habitability. They also constitute a key elemen…
A Global Kinetic Model for Cometary Comae: The Evolution of the Coma of the Rosetta Target Comet Churyumov-Gerasimenko throughout the Mission
Tenishev, Valeriy; Combi, Michael; Davidsson, Björn
The Rosetta spacecraft is en route to comet 67P/Churyumov-Gerasimenko for a rendezvous, landing, and extensive orbital phase beginning in 2014. Model studies of the coma will be required not only for planning of the mission and interpretation of spacecraft data, but also for an expectedly large amount of complementary remote observational data tha…
A Multisite Campaign to Measure Solar-like Oscillations in Procyon. I. Observations, Data Reduction, and Slow Variations
Reffert, Sabine; Butler, R. Paul; Bertaux, Jean-Loup +45 more
We have carried out a multisite campaign to measure oscillations in the F5 star Procyon A. We obtained high-precision velocity observations over more than three weeks with 11 telescopes, with almost continuous coverage for the central 10 days. This represents the most extensive campaign so far organized on any solar-type oscillator. We describe in…
Million-Degree Plasma Pervading the Extended Orion Nebula
Skinner, Stephen L.; Güdel, Manuel; Rebull, Luisa +3 more
Most stars form as members of large associations within dense, very cold (10 to 100 kelvin) molecular clouds. The nearby giant molecular cloud in Orion hosts several thousand stars of ages less than a few million years, many of which are located in or around the famous Orion Nebula, a prominent gas structure illuminated and ionized by a small grou…
Origin of Saturn's aurora: Simultaneous observations by Cassini and the Hubble Space Telescope
Coates, A. J.; Dougherty, M. K.; Nichols, J. D. +9 more
Outer planet auroras have been imaged for more than a decade, yet understanding their physical origin requires simultaneous remote and in situ observations. The first such measurements at Saturn were obtained in January 2007, when the Hubble Space Telescope imaged the ultraviolet aurora, while the Cassini spacecraft crossed field lines connected t…
Quantitative studies of the optical and UV spectra of Galactic early B supergiants. I. Fundamental parameters
Massa, D.; Prinja, R. K.; Searle, S. C. +1 more
Aims: We undertake an optical and ultraviolet spectroscopic analysis of a sample of 20 Galactic B0-B5 supergiants of luminosity classes Ia, Ib, Iab, and II. Fundamental stellar parameters are obtained from optical diagnostics and a critical comparison of the model predictions to observed UV spectral features is made.
Methods: Fundamental param…
X-Ray and Optical Microlensing in the Lensed Quasar PG 1115+080
Morgan, Nicholas D.; Dai, Xinyu; Morgan, Christopher W. +2 more
We analyzed the microlensing of the X-ray and optical emission of the lensed quasar PG 1115+080. We find that the effective radius of the X-ray emission is 1.3+ 1.1-0.5 dex smaller than that of the optical emission. Viewed as a thin disk observed at inclination angle i, the optical accretion disk has a scale length, defined b…
The X-Ray Spectral Evolution in X-Ray Binaries and Its Application to Constrain the Black Hole Mass of Ultraluminous X-Ray Sources
Wu, Qingwen; Gu, Minfeng
We investigate the relationship between the hard X-ray photon index Γ and the Eddington ratio [ξ = LX(0.5-25 keV)/LEdd] in six X-ray binaries (XRBs) with well-constrained black hole masses and distances. We find that different XRBs follow different anticorrelations between Γ and ξ when ξ is less than a critical value, while Γ…
Double Coronal Hard and Soft X-Ray Source Observed by RHESSI: Evidence for Magnetic Reconnection and Particle Acceleration in Solar Flares
Liu, Wei; Dennis, Brian R.; Jiang, Yan Wei +1 more
We present data analysis and interpretation of an M1.4 class flare observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) on 2002 April 30. This event, with its footpoints occulted by the solar limb, exhibits a rarely observed, but theoretically expected, double-source structure in the corona. The two coronal sources, obse…