Search Publications
Constraining UV Continuum Slopes of Active Galactic Nuclei with CLOUDY Models of Broad-line Region Extreme-ultraviolet Emission Lines
Shull, J. Michael; Moloney, Joshua
Understanding the composition and structure of the broad-line region (BLR) of active galactic nuclei (AGNs) is important for answering many outstanding questions in supermassive black hole evolution, galaxy evolution, and ionization of the intergalactic medium. We used single-epoch UV spectra from the Cosmic Origins Spectrograph (COS) on the Hubbl…
HOPS 136: An Edge-on Orion Protostar near the End of Envelope Infall
Manoj, P.; Kounkel, Marina; Fischer, William J. +10 more
Edge-on protostars are valuable for understanding the disk and envelope properties of embedded young stellar objects, since the disk, envelope, and envelope cavities are all distinctly visible in resolved images and well constrained in modeling. Comparing Two Micron All Sky Survey, Wide-field Infrared Survey Explorer, Spitzer, Herschel, and APEX p…
Particle Energization during Solar Maximum: Diffusive Shock Acceleration at Multiple Shocks
Zank, G. P.; Neergaard Parker, L.
We present a model for the acceleration of particles at multiple shocks using an approach related to box models. A distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles out of the box by either the met…
Star Clusters in a Nuclear Star Forming Ring: The Disappearing String of Pearls
Barway, Sudhanshu; Väisänen, Petri; Randriamanakoto, Zara
An analysis of the star cluster population in a low-luminosity early-type galaxy, NGC 2328, is presented. The clusters are found in a tight star forming nuclear spiral/ring pattern and we also identify a bar from structural two-dimensional decomposition. These massive clusters are forming very efficiently in the circumnuclear environment and they …
The Global Morphology of the Solar Wind Interaction with Comet Churyumov-Gerasimenko
Mendis, D. A.; Horányi, M.
The forthcoming Rosetta-Philae mission to comet 67P/Churyumov-Gerasimenko provides a novel opportunity to observe the variable nature of the solar wind interaction with a comet over an extended range of heliocentric distance. We use a simple analytical one-dimensional MHD model to estimate the sizes of the two most prominent features in the global…
The Flow-chart Loop: Temperature, Density, and Cooling Observables Supporting Nanoflare Coronal Heating Models
Schmelz, J. T.; Pathak, S.; Christian, G. M. +2 more
We have tested three controversial properties for a target loop observed with the Atmospheric Imaging Assembly: (1) overdense loops; (2) long-lifetime loops; and (3) multithermal loops. Our loop is overdense by a factor of about 10 compared to results expected from steady uniform heating models. If this were the only inconsistency, our loop could …
The Disk around the Brown Dwarf KPNO Tau 3
Duchêne, Gaspard; Chrysostomou, Antonio; Di Francesco, James +4 more
We present submillimeter observations of the young brown dwarfs KPNO Tau 1, KPNO Tau 3, and KPNO Tau 6 at 450 µm and 850 µm taken with the Submillimetre Common-User Bolometer Array on the James Clerk Maxwell Telescope. KPNO Tau 3 and KPNO Tau 6 have been previously identified as Class II objects hosting accretion disks, whereas KPNO Ta…
The X-Ray Eclipse Geometry of the Super-soft X-Ray Source CAL 87
Lopes de Oliveira, R.; Ribeiro, T.; Borges, B. W.
We explore XMM-Newton observations of the eclipsing super-soft X-ray source CAL 87 in order to map the accretion structures of the system. Indirect imaging techniques were applied in X-ray light curves to provide eclipse maps. The surface brightness distribution exhibits an extended and symmetric emission, and a feature is revealed from the hardes…
Comparison of Galaxy Clusters Selected by Weak-lensing, Optical Spectroscopy, and X-Rays in the Deep Lens Survey F2 Field
Jones, Christine; Geller, Margaret J.; Kurtz, Michael J. +6 more
We compare galaxy clusters selected in Chandra and XMM-Newton X-ray observations of the 4 deg2 Deep Lens Survey (DLS) F2 field to the cluster samples previously selected in the same field from a sensitive weak-lensing shear map derived from the DLS and from a detailed galaxy redshift survey—the Smithsonian Hectospec Lensing Survey (SHEL…
The Gas-rich Circumbinary Disk of HR 4049. I. A Detailed Study of the Mid-infrared Spectrum
Cami, J.; Malek, S. E.
We present a detailed analysis of the mid-infrared spectrum of the peculiar evolved object HR 4049. The full Spitzer-IRS high-resolution spectrum shows a wealth of emission with prominent features from CO2 and H2O and possible contributions from HCN and OH. We model the molecular emission and find that it originates from a ma…