Search Publications
Discovery of the Disturbed Radio Morphology in the Interacting Binary Quasar FIRST J164311.3+315618
Janiuk, Agnieszka; Kunert-Bajraszewska, Magdalena
We report the high-resolution radio observations and the subsequent analysis of the radio-loud compact steep spectrum quasar FIRST J164311.3+315618, one of the members of a binary system. The second component of the system is a radio-quiet active galactic nucleus. The projected separation of this pair is 2farcs3 (15 kpc) it is one of the smallest-…
Space Telescope Imaging Spectrograph Spectroscopy of the Central 14 pc OF NGC 3998: Evidence for an Inflow
Devereux, Nick
Prior imaging of the lenticular galaxy, NGC 3998, with the Hubble Space Telescope revealed a small, highly inclined, nuclear ionized gas disk, the kinematics of which indicate the presence of a 270 million solar mass black hole. Plausible kinematic models are used to constrain the size of the broad emission line region (BELR) in NGC 3998 by modeli…
The Abundance of Boron in Diffuse Interstellar Clouds
Lambert, D. L.; Federman, S. R.; Sheffer, Y. +1 more
We present a comprehensive survey of boron abundances in diffuse interstellar clouds from observations made with the Space Telescope Imaging Spectrograph (STIS) of the Hubble Space Telescope. Our sample of 56 Galactic sight lines is the result of a complete search of archival STIS data for the B II λ1362 resonance line, with each detection confirm…
Simulating the Effects of Initial Pitch-angle Distributions on Solar Flares
Reeves, Katharine K.; Martens, Petrus; Winter, Henry D.
In this work, we model both the thermal and non-thermal components of solar flares. The model we use, HYLOOP, combines a hydrodynamic equation solver with a non-thermal particle tracking code to simulate the thermal and non-thermal dynamics and emission of solar flares. In order to test the effects of pitch-angle distribution on flare dynamics and…
AGN Unification at z ~ 1: u - R Colors and Gradients in X-Ray AGN Hosts
Kocevski, Dale D.; Bouwens, Rychard J.; McGrath, Elizabeth J. +8 more
We present uncontaminated rest-frame u - R colors of 78 X-ray-selected active galactic nucleus (AGN) hosts at 0.5 < z < 1.5 in the Chandra Deep Fields measured with Hubble Space Telescope (HST)/Advanced Camera for Surveys/NICMOS and Very Large Telescope/ISAAC imaging. We also present spatially resolved NUV - R color gradients for a subsample…
Detection of the Detached Dust Shell of U Antliae at Mid-infrared Wavelengths with AKARI/IRC
Onaka, Takashi; Yamamura, Issei; Izumiura, Hideyuki +2 more
We report mid-infrared (MIR) imaging observations of the carbon star U Ant made with the Infrared Camera (IRC) on board AKARI. Subtraction of the artifacts and extended point-spread function of the central star reveals the detached dust shell around the carbon star at MIR wavelengths (15 and 24 µm) for the first time. The observed radial bri…
On the Flare-induced Seismicity in the Active Region NOAA 10930 and Related Enhancement of Global Waves in the Sun
García, R. A.; Tiwari, Sanjiv Kumar; Venkatakrishnan, P. +2 more
A major flare (of class X3.4) occurred on 2006 December 13 in the active region NOAA 10930. This flare event has remained interesting to solar researchers for studies related to particle acceleration during the flare process and the reconfiguration of magnetic fields as well as fine-scale features in the active region. The energy released during f…
The Curious Case of the Alpha Persei Corona: A Dwarf in Supergiant's Clothing?
Ayres, Thomas R.
Alpha Persei (HD 20902: F5 Iab) is a luminous, nonvariable supergiant located at the blue edge of the Cepheid instability strip. It is one of the brightest coronal X-ray sources in the young open cluster bearing its name, yet warm supergiants as a class generally avoid conspicuous high-energy activity. The Cosmic Origins Spectrograph on the Hubble…
Blue Luminous Stars in Nearby Galaxies—UIT 005: A Possible Link to the Luminous Blue Variable Stage
Meynet, G.; Lennon, D. J.; Herrero, A. +2 more
A detailed study of the blue supergiant UIT 005 (B2-2.5Ia+) in M 33 is presented. The results of our quantitative spectral analysis indicate that the star is a very luminous (log L/L sun ~ 5.9 dex) and massive (M ~ 50 M sun) object, showing a very high nitrogen-to-oxygen ratio in its surface (N/O~8, by mass). Based…
The Evolution of Radio Galaxies and X-Ray Point Sources in Coma Cluster Progenitors since z ~ 1.2
Stocke, John T.; Evrard, August E.; Hart, Quyen N. +2 more
Using Chandra imaging spectroscopy and Very Large Array (VLA) L-band radio maps, we have identified radio sources at P 1.4 GHz >= 5 × 1023 W Hz-1 and X-ray point sources (XPSs) at L 0.3-8 keV >= 5 × 1042 erg s-1 in L > L* galaxies in 12 high-redshift (0.4 < z < 1.2) c…