Search Publications
Decadal variations in a Venus general circulation model
Lebonnois, Sebastien; Schubert, Gerald; Parish, Helen F. +3 more
The Community Atmosphere Model (CAM), a 3-dimensional Earth-based climate model, has been modified to simulate the dynamics of the Venus atmosphere. The most current finite volume version of CAM is used with Earth-related processes removed, parameters appropriate for Venus introduced, and some basic physics approximations adopted. A simplified New…
Wind Structure and Luminosity Variations in the Wolf-Rayet/Luminous Blue Variable HD 5980
Hillier, D. John; Morrell, Nidia; Gamen, Roberto +3 more
Over the past 40 years, the massive luminous blue variable/Wolf-Rayet system HD 5980 in the Small Magellanic Cloud (SMC) has undergone a long-term S Doradus-type variability cycle and two brief and violent eruptions in 1993 and 1994. In this paper we analyze a collection of UV and optical spectra obtained between 1979 and 2009 and perform CMFGEN m…
Subsurface Velocity of Emerging and Decaying Active Regions
Howe, R.; Komm, R.; Hill, F.
We study the temporal variation of subsurface flows of 828 active regions and 977 quiet regions. The horizontal flows cover a range of depths from the surface to about 16 Mm and are determined by analyzing Global Oscillation Network Group high-resolution Doppler data with ring-diagram analyses. The vertical velocity component is derived from the d…
Evolution of the dust coma in comet 67P/Churyumov-Gerasimenko before the 2009 perihelion
Vincent, J. -B.; Schulz, R.; Licandro, J. +5 more
Context. Comet 67P/Churyumov-Gerasimenko is the main target of ESA's Rosetta mission and will be encountered in May 2014. Because the spacecraft will orbit the comet nucleus before and after release of the lander Philae, it is necessary to know the conditions in the coma.
Aims: We study the dust environment, including the dust production rate…
A Saturnian cam current system driven by asymmetric thermospheric heating
Smith, C. G. A.
We show that asymmetric heating of Saturn's thermosphere can drive a current system consistent with the magnetospheric ‘cam’ proposed by Espinosa, Southwood & Dougherty. A geometrically simple heating distribution is imposed on the Northern hemisphere of a simplified three-dimensional global circulation model of Saturn's thermosphere. Currents…
On the origin of correlated X-ray/VHE emission from LS I +61 303
Paredes, J. M.; Zabalza, V.; Bosch-Ramon, V.
Context. The MAGIC collaboration recently reported correlated X-ray and very high-energy (VHE) gamma-ray emission from the gamma-ray binary LS I +61 303 during ~60% of one orbit. These observations suggest that the emission in these two bands has its origin in a single particle population.
Aims: We aim at improving our understanding of the so…
Spatial Distribution and Evolution of the Stellar Populations and Candidate Star Clusters in the Blue Compact Dwarf I Zwicky 18
Saha, A.; Tosi, M.; Clementini, G. +7 more
The evolutionary properties and spatial distribution of I Zwicky 18 (IZw18) stellar populations are analyzed by means of Hubble Space Telescope/Advanced Camera for Surveys deep and accurate photometry. A comparison of the resulting color-magnitude diagrams (CMDs) with stellar evolution models indicates that stars of all ages are present in all the…
On the nature of the absorber in IRAS 09104+4109: the X-ray and mid-infrared view
Maiolino, R.; Pozzi, F.; Fiore, F. +8 more
We present a long (≈76 ks) Chandra observation of IRAS 09104+4109, a hyperluminous galaxy, optically classified as a type 2 active galactic nuclei (AGN) hosted in a cD galaxy in a cluster at z= 0.442. We also report on the results obtained by fitting its broad-band spectral energy distribution. The Compton-thick nature of this source (which has be…
Flares and Their Underlying Magnetic Complexity
Golub, Leon; Sylwester, Barbara; Sylwester, Janusz +5 more
SphinX (Solar PHotometer IN X-rays), a full-disk-integrated spectrometer, observed 137 flare-like/transient events with active region (AR) 11024 being the only AR on disk. The Hinode X-Ray Telescope (XRT) and Solar Optical Telescope observe 67 of these events and identified their location from 12:00 UT on July 3 through 24:00 UT 2009 July 7. We fi…
Hubble Space Telescope Imaging and Spectral Analysis of Two Brown Dwarf Binaries at the L Dwarf/T Dwarf Transition
Burgasser, Adam J.; Gizis, John E.; Bardalez-Gagliuffi, Daniella C.
We present a detailed examination of the brown dwarf multiples 2MASS J08503593+1057156 and 2MASS J17281150+3948593, both suspected of harboring components that straddle the L dwarf/T dwarf transition. Resolved photometry from Hubble Space Telescope/NICMOS shows opposite trends in the relative colors of the components, with the secondary of 2MASS J…