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Cassini UVIS Stellar Occultation Observations of Saturn's Rings
Sremčević, M.; Colwell, J. E.; Esposito, L. W. +3 more
The Cassini spacecraft's Ultraviolet Imaging Spectrograph (UVIS) includes a high-speed photometer (HSP) that has observed more than 100 stellar occultations by Saturn's rings. Here, we document a standardized technique applied to the UVIS-HSP ring occultation datasets delivered to the Planetary Data System as higher level data products. These obse…
The XMM-Newton Wide Angle Survey (XWAS): the X-ray spectrum of type-1 AGN
Ebrero, J.; Page, M. J.; Carrera, F. J. +7 more
Aims: We discuss the broad band X-ray properties of one of the largest samples of X-ray selected type-1 AGN to date (487 objects in total), drawn from the XMM-Newton Wide Angle Survey (XWAS). The objects presented in this work cover 2-10 keV (rest-frame) luminosities from 1042-1045 erg s-1 and are detected up …
Mountains on Titan: Modeling and observations
Showman, Adam P.; Lopes, Rosaly M. C.; Radebaugh, Jani +5 more
We have developed a thermal model of Titan's interior to study changes in volume during partial freezing or melting of a subsurface ocean due to heat flux variations from the interior. We find that the long-term cooling of Titan can cause global volume contraction ΔV/V ∼0.01. We then simulate two-dimensional contractional deformation of Titan's ic…
Evidence of small-scale magnetic concentrations dragged by vortex motion of solar photospheric plasma
Vargas Domínguez, S.; Balmaceda, L.; Domingo, V. +2 more
Vortex-type motions have been measured by tracking bright points in high-resolution observations of the solar photosphere. These small-scale motions are thought to be determinant in the evolution of magnetic footpoints and their interaction with plasma and therefore likely to play a role in heating the upper solar atmosphere by twisting magnetic f…
Locating the Accretion Footprint on a Herbig Ae Star: MWC 480
Bouret, J. -C.; Ménard, F.; Kim, S. +27 more
Accretion is a fundamental process which establishes the dynamics of the protoplanetary disk and the final properties of the forming star. In solar-type stars, the star-disk coupling is determined by the magnetic field structure, which is responsible for funneling material from the disk midplane to higher latitudes on the star. Here, we use pan-ch…
New Observations of the Very Luminous Supernova 2006gy: Evidence for Echoes
Bloom, J. S.; Smith, N.; Filippenko, A. V. +4 more
Supernova (SN) 2006gy was a hydrogen-rich core-collapse SN that remains one of the most luminous optical SNe ever observed. The total energy budget (>2 × 1051 erg radiated in the optical alone) poses many challenges for standard SN theory. We present new ground-based near-infrared (NIR) observations of SN 2006gy, as well as a single …
Angular Diameters and Effective Temperatures of 25 K Giant Stars from the CHARA Array
Guenther, Eike W.; Hatzes, Artie P.; Goldfinger, P. J. +10 more
Using Georgia State University's Center for High Angular Resolution Astronomy Array interferometer, we measured angular diameters for 25 giant stars, six of which host exoplanets. The combination of these measurements and Hipparcos parallaxes produces physical linear radii for the sample. Except for two outliers, our values match angular diameters…
Optical-Ultraviolet Spectrum and Proper Motion of the Middle-aged Pulsar B1055-52
Mignani, R. P.; Pavlov, G. G.; Kargaltsev, O.
PSR B1055-52 is a middle-aged (τ = 535 kyr) radio, X-ray, and γ-ray pulsar showing X-ray thermal emission from the neutron star (NS) surface. A candidate optical counterpart to PSR B1055-52 was proposed by Mignani and coworkers based on Hubble Space Telescope (HST) observations performed in 1996, in one spectral band only. We report on HST observa…
Clouds on Titan during the Cassini prime mission: A complete analysis of the VIMS data
Brown, Michael E.; Schaller, Emily L.; Roberts, Jessica E.
We use data from the VIMS instrument on board the Cassini spacecraft to construct high sensitivity and high spatial-resolution maps of the locations of tropospheric clouds on Titan in the late northern winter season during which the Cassini prime mission took place. These observations show that, in this season, clouds on Titan are strongly hemisph…
A New Extensive Catalog of Optically Variable Active Galactic Nuclei in the GOODS Fields and a New Statistical Approach to Variability Selection
Grogin, Norman A.; Koekemoer, Anton M.; Villforth, Carolin
Variability is a property shared by practically all active galactic nuclei (AGNs). This makes variability selection a possible technique for identifying AGNs. Given that variability selection makes no prior assumption about spectral properties, it is a powerful technique for detecting both low-luminosity AGNs in which the host galaxy emission is d…