Search Publications
Coronal Cells
Warren, H. P.; Sheeley, N. R., Jr.
We have recently noticed cellular features in Fe XII 193 Å images of the 1.2 MK corona. They occur in regions bounded by a coronal hole and a filament channel, and are centered on flux elements of the photospheric magnetic network. Like their neighboring coronal holes, these regions have minority-polarity flux that is ~0.1-0.3 times their flux of …
Hubble Space Telescope Observations of the Stellar Distribution near Sgr A*
Yusef-Zadeh, F.; Wardle, M.; Bushouse, H.
Sgr A* is embedded within the nuclear cluster, which consists of a mixture of evolved and young populations of stars dominating the light over a wide range of angular scales. Here we present Hubble Space Telescope/NICMOS data to study the surface brightness distribution of stellar light within the inner 10'' of Sgr A* at 1.45 µm, 1.7 µ…
The Resolved Stellar Population in 50 Regions of M83 from HST/WFC3 Early Release Science Observations
Mutchler, Max; McCarthy, Patrick J.; Calzetti, Daniela +22 more
We present a multi-wavelength photometric study of ~15,000 resolved stars in the nearby spiral galaxy M83 (NGC 5236, D = 4.61 Mpc) based on Hubble Space Telescope Wide Field Camera 3 observations using four filters: F336W, F438W, F555W, and F814W. We select 50 regions (an average size of 260 pc by 280 pc) in the spiral arm and inter-arm areas of M…
Power Spectra of Velocities and Magnetic Fields on the Solar Surface and their Dependence on the Unsigned Magnetic Flux Density
Katsukawa, Y.; Orozco Suárez, D.
We have performed power spectral analysis of surface temperatures, velocities, and magnetic fields, using spectropolarimetric data taken with the Hinode Solar Optical Telescope. When we make power spectra in a field of view covering the supergranular scale, kinetic and thermal power spectra have a prominent peak at the granular scale while the mag…
Suzaku X-Ray Imaging of the Extended Lobe in the Giant Radio Galaxy NGC 6251 Associated with the Fermi-LAT Source 2FGL J1629.4+8236
Cheung, C. C.; Kataoka, J.; Stawarz, Ł. +7 more
We report the results of a Suzaku X-ray imaging study of NGC 6251, a nearby giant radio galaxy with intermediate FR I/II radio properties. Our pointing direction was centered on the γ-ray emission peak recently discovered with the Fermi Large Area Telescope (LAT) around the position of the northwest (NW) radio lobe 15 arcmin offset from the nucleu…
Observations of Plasma Upflow in a Warm Loop with Hinode/EIS
Del Zanna, Giulio; Tripathi, Durgesh; Mason, Helen E. +1 more
A complete understanding of Doppler shift in active region loops can help probe the basic physical mechanism involved into the heating of those loops. Here, we present observations of upflows in coronal loops detected in a range of temperatures (log T = 5.8-6.2). The loop was not discernible above these temperatures. The speed of upflow was strong…
Interstellar Silicate Dust in the z = 0.89 Absorber toward PKS 1830-211: Crystalline Silicates at High Redshift?
York, Donald G.; Kulkarni, Varsha P.; Welty, Daniel E. +3 more
We present evidence of a >10σ detection of the 10 µm silicate dust absorption feature in the spectrum of the gravitationally lensed quasar PKS 1830-211, produced by a foreground absorption system at redshift 0.886. We have examined more than 100 optical depth templates, derived from both observations of Galactic and extragalactic sources …
GALEX-selected Lyman Break Galaxies at z ~ 2: Comparison with Other Populations
Nesvadba, N.; Haberzettl, L.; Lehnert, M. D. +2 more
We present results of a search for bright Lyman break galaxies (LBGs) at 1.5 <= z <= 2.5 in the GOODS-S field using an NUV-dropout technique in combination with color selection. We derived a sample of 73 LBG candidates. We compare our selection efficiencies to BM/BX and BzK methods (techniques solely based on ground-based data sets), and fin…
CO and H2 Absorption in the AA Tauri Circumstellar Disk
Herczeg, Gregory J.; Brown, Alexander; France, Kevin +7 more
The direct study of molecular gas in inner protoplanetary disks is complicated by uncertainties in the spatial distribution of the gas, the time variability of the source, and the comparison of observations across a wide range of wavelengths. Some of these challenges can be mitigated with far-ultraviolet spectroscopy. Using new observations obtain…
X-Ray Binaries and Star Clusters in the Antennae: Optical Cluster Counterparts
Whitmore, Bradley C.; Chandar, Rupali; Rangelov, Blagoy +1 more
We compare the locations of 82 X-ray binaries (XRBs) detected in the merging Antennae galaxies by Zezas et al., based on observations taken with the Chandra X-Ray Observatory, with a catalog of optically selected star clusters presented by Whitmore et al., based on observations taken with the Hubble Space Telescope. Within the 2σ positional uncert…