Search Publications
Uncovering the Wave Nature of the EIT Wave for the 2010 January 17 Event through Its Correlation to the Background Magnetosonic Speed
Wu, S. T.; Feng, X. S.; Jiang, C. W. +3 more
An EIT wave, which typically appears as a diffuse brightening that propagates across the solar disk, is one of the major discoveries of the Extreme ultraviolet Imaging Telescope on board the Solar and Heliospheric Observatory. However, the physical nature of the so-called EIT wave continues to be debated. In order to understand the relationship be…
Far-ultraviolet Number Counts of Field Galaxies
Gardner, Jonathan P.; Teplitz, Harry I.; de Mello, Duilia F. +2 more
The far-ultraviolet (FUV) number counts of galaxies constrain the evolution of the star formation rate density of the universe. We report the FUV number counts computed from FUV imaging of several fields including the Hubble Ultra Deep Field, the Hubble Deep Field North, and small areas within the GOODS-North and South fields. These data were obta…
Evolution of Spinning and Braiding Helicity Fluxes in Solar Active Region NOAA 10930
Ravindra, B.; Yoshimura, Keiji; Dasso, Sergio
The line-of-sight magnetograms from Solar Optical Telescope Narrowband Filter Imager observations of NOAA Active Region 10930 have been used to study the evolution of spinning and braiding helicities over a period of five days starting from 2006 December 9. The north (N) polarity sunspot was the follower and the south (S) polarity sunspot was the …
Ultra-compact Dwarfs in the Fossil Group NGC 1132
Madrid, Juan P.
Eleven ultra-compact dwarf (UCD) and 39 extended star cluster candidates are found to be associated with the galaxy NGC 1132. This giant elliptical galaxy is the remnant of a fossil group. UCD and extended star cluster candidates are identified through the analysis of their structural parameters, colors, spatial distribution, and luminosity using …
Unveiling the Nature of IGR J17177-3656 with X-Ray, Near-infrared, and Radio Observations
Nowak, M. A.; Chaty, S.; Rodriguez, J. +6 more
We report on the first broadband (1-200 keV) simultaneous Chandra-INTEGRAL observations of the recently discovered hard X-ray transient IGR J17177-3656 that took place on 2011 March 22, about two weeks after the source discovery. The source had an average absorbed 1-200 keV flux of about 8 × 10-10 erg cm-2 s-1. We …
A Method for the Study of Accretion Disk Emission in Cataclysmic Variables. I. The Model
Hillier, D. John; Hubeny, Ivan; Puebla, Raúl E. +1 more
We have developed a spectrum synthesis method for modeling the ultraviolet (UV) emission from the accretion disk from cataclysmic variables (CVs). The disk is separated into concentric rings, with an internal structure from the Wade & Hubeny disk-atmosphere models. For each ring, a wind atmosphere is calculated in the comoving frame with a ver…
First VLBI Detection of the Radio Remnant of Supernova 1987A: Evidence for Small-scale Features
Gaensler, B. M.; Ng, C. -Y.; Staveley-Smith, L. +5 more
We present a detailed analysis of the first very long baseline interferometry (VLBI) detection of the radio remnant of supernova 1987A. The VLBI data taken in 2007 and 2008 at 1.4 and 1.7 GHz, respectively, provide images sensitive to angular scales from 0farcs1 to 0farcs7, the highest resolution to date at radio frequencies. The results reveal tw…
The Mass-Radius Relation for Star-forming Galaxies at z ~ 1.5-3.0
Shapley, Alice E.; Steidel, Charles C.; Law, David R. +1 more
We present early results from a Hubble Space Telescope WFC3/IR imaging survey of star-forming galaxies in the redshift range 1.5 < z < 3.0. When complete, this survey will consist of 42 orbits of F160W imaging distributed amongst 10 survey fields on the line of sight to bright background QSOs, covering 65 arcmin2 to a depth of 27.…
AKARI Near-infrared Spectral Observations of Shocked H2 Gas of the Supernova Remnant IC 443
Koo, Bon-Chul; Lee, Ho-Gyu; Seon, Kwang-Il +1 more
We present near-infrared (2.5-5.0 µm) spectra of shocked H2 gas in the supernova remnant IC 443, obtained with the satellite AKARI. Three shocked clumps—known as B, C, and G—and one background region were observed, and only H2 emission lines were detected. Except in clump B, the extinction-corrected level population sho…
Investigating the Nuclear Activity of Barred Spiral Galaxies: The Case of NGC 1672
Zezas, A.; Brandt, W. N.; Roberts, T. P. +7 more
We have performed an X-ray study of the nearby barred spiral galaxy NGC 1672, primarily to ascertain the effect of the bar on its nuclear activity. We use both Chandra and XMM-Newton observations to investigate its X-ray properties, together with supporting high-resolution optical imaging data from the Hubble Space Telescope (HST), infrared imagin…