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Relativistic Accretion Disk Models of High-State Black Hole X-Ray Binary Spectra
Hubeny, Ivan; Davis, Shane W.; Turner, Neal J. +1 more
We present calculations of non-LTE, relativistic accretion disk models applicable to the high/soft state of black hole X-ray binaries. We include the effects of thermal Comptonization and bound-free and free-free opacities of all abundant ion species. Taking into account the relativistic propagation of photons from the local disk surface to an obs…
HST STIS Spectroscopy of the Triple Nucleus of M31: Two Nested Disks in Keplerian Rotation around a Supermassive Black Hole
Richstone, Douglas; Kormendy, John; Lauer, Tod R. +12 more
We present Hubble Space Telescope (HST) spectroscopy of the nucleus of M31 obtained with the Space Telescope Imaging Spectrograph (STIS). Spectra that include the Ca II infrared triplet (λ~=8500 Å) see only the red giant stars in the double brightness peaks P1 and P2. In contrast, spectra taken at λ~=3600-5100 Å are sensitive to the tiny blue nucl…
Stellar Lyα Emission Lines in the Hubble Space Telescope Archive: Intrinsic Line Fluxes and Absorption from the Heliosphere and Astrospheres
Zank, Gary P.; Redfield, Seth; Wood, Brian E. +2 more
We search the Hubble Space Telescope (HST) archive for previously unanalyzed observations of stellar H I Lyα emission lines, our primary purpose being to look for new detections of Lyα absorption from the outer heliosphere and to also search for analogous absorption from the astrospheres surrounding the observed stars. The astrospheric absorption …
Stellar Populations in 10 Clump-Cluster Galaxies of the Hubble Ultra Deep Field
Elmegreen, Bruce G.; Elmegreen, Debra Meloy
Color-color diagrams for the clump and interclump emission in 10 clump-cluster galaxies of the Hubble Ultra Deep Field (UDF) are made from B,V, i, and z images and compared with models to determine redshifts, star formation histories, and galaxy masses. These galaxies are members of a class dominated by 5-10 giant clumps, with no exponential disk …
Radar Soundings of the Ionosphere of Mars
Gurnett, D. A.; Persoon, A. M.; Averkamp, T. F. +8 more
We report the first radar soundings of the ionosphere of Mars with the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on board the orbiting Mars Express spacecraft. Several types of ionospheric echoes are observed, ranging from vertical echoes caused by specular reflection from the horizontally stratified ionosphere…
Differentiation of the asteroid Ceres as revealed by its shape
Russell, C. T.; Stern, S. A.; Young, E. F. +4 more
The accretion of bodies in the asteroid belt was halted nearly 4.6billion years ago by the gravitational influence of the newly formed giant planet Jupiter. The asteroid belt therefore preserves a record of both this earliest epoch of Solar System formation and variation of conditions within the solar nebula. Spectral features in reflected sunligh…
Cluster observations of electron holes in association with magnetotail reconnection and comparison to simulations
Balogh, A.; Lucek, E.; André, M. +8 more
Large-amplitude (up to ∼50 mV/m) solitary waves, identified as electron holes, have been observed during waveform captures on two of the four Cluster satellites during several plasma sheet encounters that have been identified as the passage of a magnetotail reconnection x line. The electron holes were seen near the outer edge of the plasma sheet, …
The Age Distribution of Massive Star Clusters in the Antennae Galaxies
Whitmore, Bradley C.; Fall, S. Michael; Chandar, Rupali
We determine the age distribution of star clusters in the Antennae galaxies (NGC 4038/9) for two mass-limited samples (M>3×104 Msolar and M>2×105 Msolar). This is based on integrated broadband UBVI and narrowband Hα photometry from deep images taken with the Hubble Space Telescope. We find that the…
Did most present-day spirals form during the last 8 Gyr?. A formation history with violent episodes revealed by panchromatic observations
Elbaz, D.; Cesarsky, C.; Flores, H. +3 more
Studies of distant galaxies have shown that ellipticals and large spirals (Schade et al. \cite{Schade99}, ApJ, 525, 31; Lilly et al. \cite{Lilly98}, ApJ, 500, 75) were already in place 8 Gyr ago, leading to a very modest recent star formation (Brinchmann & Ellis \cite{Brinchmann00}, ApJ, 536, L77) in intermediate mass galaxies (3-30 × 101…
Cluster observations of an intense normal component of the electric field at a thin reconnecting current sheet in the tail and its role in the shock-like acceleration of the ion fluid into the separatrix region
Balogh, A.; Lucek, E. A.; Reme, H. +12 more
Measurements from the Cluster spacecraft of electric fields, magnetic fields, and ions are used to study the structure and dynamics of the reconnection region in the tail at distances of ∼18 RE near 22.4 MLT on 1 October 2001. This paper focuses on measurements of the large amplitude normal component of the electric field observed in th…