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The Lack of Diffuse, Non-thermal Hard X-ray Emission in the Coma Cluster: The Swift Burst Alert Telescope's Eye View
Sarazin, Craig L.; Okajima, Takashi; Wik, Daniel R. +5 more
The Coma Cluster of galaxies hosts the brightest radio halo known and has therefore been the target of numerous searches for associated inverse Compton (IC) emission, particularly at hard X-ray energies where the IC signal must eventually dominate over thermal emission. The most recent search with the Suzaku Hard X-ray Detector failed to confirm p…
Three-dimensional Structure of a Solar Active Region from Spatially and Spectrally Resolved Microwave Observations
Gary, Dale E.; Georgoulis, Manolis K.; Tun, Samuel D.
We report on the structure of the solar atmosphere above active region (AR) 10923, observed on 2006 November 10, as deduced from multi-wavelength studies including combined microwave observations from the Very Large Array (VLA) and the Owens Valley Solar Array (OVSA). The VLA observations provide excellent image quality at a few widely spaced freq…
GSC 07396-00759 = V4046 Sgr C[D]: A Wide-separation Companion to the Close T Tauri Binary System V4046 Sgr AB
Donati, J. -F.; Audard, M.; Güdel, M. +13 more
We explore the possibility that GSC 07396-00759 (spectral type M1e) is a widely separated (~2farcm82, or projected separation ~12,350 AU) companion to the "old" (age ~12 Myr) classical T Tauri binary system V4046 Sgr AB, as suggested by the proximity and similar space motions of the two systems. If the two systems are equidistant and coeval, then …
Structure and Dynamics of the 2010 July 11 Eclipse White-light Corona
Seaton, D. B.; Golub, L.; Lucas, R. +8 more
The white-light corona (WLC) during the total solar eclipse on 2010 July 11 was observed by several teams in the Moon's shadow stretching across the Pacific Ocean and a number of isolated islands. We present a comparison of the WLC as observed by eclipse teams located on the Tatakoto Atoll in French Polynesia and on Easter Island, 83 minutes later…
Differential Emission Measure Analysis of a Polar Coronal Hole during the Solar Minimum in 2007
Hahn, M.; Savin, D. W.; Landi, E.
We have performed a differential emission measure (DEM) analysis for a polar coronal hole observed during solar minimum in 2007. Five observations are analyzed spanning the coronal hole from the central meridian to the boundary with the quiet-Sun corona. The observed heights ranged from 1.05 to 1.20 R sun. The analysis shows that the pl…
Spatial Distribution and Evolution of the Stellar Populations and Candidate Star Clusters in the Blue Compact Dwarf I Zwicky 18
Saha, A.; Tosi, M.; Clementini, G. +7 more
The evolutionary properties and spatial distribution of I Zwicky 18 (IZw18) stellar populations are analyzed by means of Hubble Space Telescope/Advanced Camera for Surveys deep and accurate photometry. A comparison of the resulting color-magnitude diagrams (CMDs) with stellar evolution models indicates that stars of all ages are present in all the…
Flares and Their Underlying Magnetic Complexity
Golub, Leon; Sylwester, Barbara; Sylwester, Janusz +5 more
SphinX (Solar PHotometer IN X-rays), a full-disk-integrated spectrometer, observed 137 flare-like/transient events with active region (AR) 11024 being the only AR on disk. The Hinode X-Ray Telescope (XRT) and Solar Optical Telescope observe 67 of these events and identified their location from 12:00 UT on July 3 through 24:00 UT 2009 July 7. We fi…
The Dark Side of QSO Formation at High Redshifts
Trenti, Michele; Hoffman, Yehuda; Shlosman, Isaac +1 more
Observed high-redshift QSOs, at z ~ 6, may reside in massive dark matter (DM) halos of more than 1012 M sun and are thus expected to be surrounded by overdense regions. In a series of 10 constrained simulations, we have tested the environment of such QSOs. The usage of constrained realizations has enabled us to address the is…
The Connection between X-Ray Binaries and Star Clusters in NGC 4449
Chandar, Rupali; Rangelov, Blagoy; Prestwich, Andrea H.
We present 23 candidate X-ray binaries with luminosities down to 1.8 × 1036 erg s-1, in the nearby starburst galaxy NGC 4449, from observations totaling 105 ks taken with the ACIS-S instrument on the Chandra Space Telescope. We determine count rates, luminosities, and colors for each source, and perform spectral fits for sour…
A Temporal Study of the Oxygen-rich Pulsating Variable Asymptotic Giant Branch Star, T Cep: Investigation on Dust Formation and Dust Properties
Onaka, Takashi; Speck, Angela K.; Guha Niyogi, Suklima
Pulsation is believed to be the leading cause of dusty mass loss from asymptotic giant branch stars. We present a temporal study of T Cep, a long-period Mira variable, using seven Infrared Space Observatory Short Wavelength Spectrometer spectra, covering a 16 month period over a single pulsation cycle. The observed spectral dust features change ov…