Search Publications
Orbit-based Dynamical Models of the Sombrero Galaxy (NGC 4594)
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +6 more
We present axisymmetric, orbit-based models to study the central black hole (BH), stellar mass-to-light ratio (M/L), and dark matter (DM) halo of NGC 4594 (M104, the Sombrero Galaxy). For stellar kinematics, we use published high-resolution kinematics of the central region taken with the Hubble Space Telescope, newly obtained Gemini long-slit spec…
Optical Polarization Mapping Toward the Interface Between the Local Cavity and Loop I
Santos, Fábio P.; Corradi, Wagner; Reis, Wilson
The Sun is located inside an extremely low density and quite irregular volume of the interstellar medium, known as the Local Cavity (LC). It has been widely believed that some kind of interaction could be occurring between the LC and Loop I, a nearby superbubble seen in the direction of the Galactic center. As a result of such interaction, a wall …
Uncovering Obscured Active Galactic Nuclei in Homogeneously Selected Samples of Seyfert 2 Galaxies
Ptak, A.; Sonnentrucker, P.; Heckman, T. M. +4 more
We have analyzed archival Chandra and XMM-Newton data for two nearly complete homogeneously selected samples of type 2 Seyfert galaxies (Sy2s). These samples were selected based on intrinsic active galactic nuclei (AGNs) flux proxies: a mid-infrared (MIR) sample from the original IRAS 12 µm survey and an optical ([O III]λ 5007 flux limited) …
Cosmic Origins Spectrograph Detection of Ne VIII Tracing Warm-Hot Gas Toward PKS 0405-123
Sembach, Kenneth R.; Savage, Blair D.; Shull, J. Michael +7 more
We report on the detection of Ne VIII in the Hubble Space Telescope/Cosmic Origins Spectrograph (COS) spectrum of the intervening absorption system at z = 0.495096 toward PKS 0405-123 (z em = 0.5726). The high signal-to-noise COS spectrum also covers absorption from H I, C III, O III, O IV, and O VI associated with this multiphase syste…
Hinode Observations Suggesting the Presence of a Local Small-scale Turbulent Dynamo
Lites, B. W.
Analysis of observations from the Hinode/Solar Optical Telescope spectropolarimeter (SP) yields results that are consistent with the operation of a small-scale turbulent dynamo in the upper solar convection zone. Examination of 45 Hinode data sets obtained in 2007 reveals only a very small correlation of the net polarity imbalance of the regions o…
A Cold, Tenuous Solar Flare: Acceleration Without Heating
Kontar, Eduard P.; Fleishman, Gregory D.; Nita, Gelu M. +1 more
We report the observation of an unusual cold, tenuous solar flare, which reveals itself via numerous and prominent non-thermal manifestations, while lacking any noticeable thermal emission signature. RHESSI hard X-rays and 0.1-18 GHz radio data from OVSA and Phoenix-2 show copious electron acceleration (1035 electrons s-1 abo…
A View of the Narrow-line Region in the Infrared: Active Galactic Nuclei with Resolved Fine-structure Lines in the Spitzer Archive
Elbaz, D.; Sturm, E.; Armus, L. +5 more
We queried the Spitzer archive for high-resolution observations with the Infrared Spectrograph of optically selected active galactic nuclei (AGNs) for the purpose of identifying sources with resolved fine-structure lines that would enable studies of the narrow-line region (NLR) at mid-infrared wavelengths. By combining 298 Spitzer spectra with 6 I…
Evolution of Brightest Cluster Galaxy Structural Parameters in the Last ~6 Gyr: Feedback Processes Versus Merger Events
Cava, A.; Varela, J.; Moles, M. +4 more
We present results on the evolution of the structural parameters of two samples of brightest cluster galaxies (BCGs) in the last 6 Gyr. The nearby sample of BCGs consists of 69 galaxies from the WINGS survey spanning a redshift range of 0.04 < z < 0.07. The intermediate-redshift (0.3 < z < 0.6) sample is formed by 20 BCGs extracted fro…
Characterization of Seven Ultra-wide Trans-Neptunian Binaries
Kavelaars, J. J.; Petit, Jean-Marc; Jones, Lynne +3 more
The low-inclination component of the Classical Kuiper Belt is host to a population of extremely widely separated binaries. These systems are similar to other trans-Neptunian binaries (TNBs) in that the primary and secondary components of each system are of roughly equal size. We have performed an astrometric monitoring campaign of a sample of seve…
X-Ray Activity Phased with Planet Motion in HD 189733?
Günther, H. M.; Pillitteri, I.; Cohen, O. +2 more
We report on the follow-up XMM-Newton observation of the planet-hosting star HD 189733 we obtained in 2011 April. We observe a flare just after the secondary transit of the hot Jupiter. This event shares the same phase and many of the characteristics of the flare we observed in 2009. We suggest that a systematic interaction between planet and stel…