Search Publications
Dynamical Constraints on the Component Masses of the Cataclysmic Variable WZ Sagittae
Howell, Steve B.; Sion, Edward M.; Gänsicke, Boris T. +3 more
We present phase-resolved spectroscopy of the short-period cataclysmic variable WZ Sge obtained with the Hubble Space Telescope. We were able to resolve the orbital motion of a number of absorption lines that likely probe the environment near the accreting white dwarf. The radial velocities derived from simultaneous fits to 13 absorption lines ind…
A Strong-Lens Survey in AEGIS: The Influence of Large-Scale Structure
Davis, Marc; Willmer, Christopher N. A.; Coil, Alison L. +10 more
We report on a visual search for galaxy-scale strong gravitational lenses over 650 arcmin2 of HST ACS (V606 and I814) imaging in the DEEP2 Extended Groth Strip. This field has Keck DEIMOS spectroscopy of ~14,000 galaxies (~75% complete to RAB<24.1). We identify three strong galaxy-galaxy lenses: HST J…
Vector Magnetic Fields of Moving Magnetic Features and Flux Removal from a Sunspot
Kubo, M.; Tsuneta, S.; Shimizu, T.
Moving magnetic features (MMFs) are small photospheric magnetic elements moving outward in the zone (moat region) surrounding mature sunspots. Vector magnetic fields and horizontal motion of the classical MMFs (called isolated MMFs hereafter) are investigated using coordinated ASP and MDI observations. Their magnetic and velocity properties are co…
Optical Studies of the Ultraluminous X-Ray Source NGC 1313 X-2
Kaaret, Philip; Miller, Jon; Liu, Ji-Feng +1 more
NGC 1313 X-2 was among the first ultraluminous X-ray sources discovered, and has been a frequent target of X-ray and optical observations. Using the HST ACS multiband observations, this source is identified with a unique counterpart within an error circle of 0.2". The counterpart is a blue star on the edge of a young cluster of <=107…
Nonlinear Interaction of Minor Heavy Ions with Kinetic Alfvén Waves and Their Anisotropic Energization in Coronal Holes
Wu, D. J.; Yang, L.
Some recent observations of the solar corona suggest that minor heavy ions undergo an anisotropic and mass-charge dependent energization in the extended corona. In this paper we investigate the nonlinear interaction of minor heavy ions with kinetic Alfvén waves (KAWs) in the extended corona where plasma is low-β, in particular the ion energization…
How Hot is the Wind from TW Hydrae?
Herczeg, Gregory J.; Johns-Krull, Christopher M.
It has recently been suggested that the winds from classical T Tauri stars in general, and the wind from TW Hya in particular, reaches temperatures of 300,000 K while maintaining a mass-loss rate of ~10-11 Msolar yr-1 or larger. If confirmed, this would place strong new requirements on wind launching and heating mo…
Chandra X-Ray Sources in the Collapsed-Core Globular Cluster M30 (NGC 7099)
Heinke, Craig O.; Cohn, Haldan N.; Lugger, Phyllis M. +2 more
We report the detection of six discrete, low-luminosity (LX<1033 ergs s-1) X-ray sources, located within 12" of the center of the collapsed-core globular cluster M30 (NGC 7099), and a total of 13 sources within the half-mass radius, from a 50 ks Chandra ACIS-S exposure. Three sources lie within the very small up…
X-Ray Luminosity Functions of Normal Galaxies in the Great Observatories Origins Deep Survey
Mobasher, Bahram; Bauer, Franz; Norman, Colin +2 more
We present soft (0.5-2 keV) X-ray luminosity functions (XLFs) in the Great Observatories Origins Deep Survey (GOODS) fields derived for galaxies at z~0.25 and 0.75. SED fitting was used to estimate photometric redshifts and separate galaxy types, resulting in a sample of 40 early-type galaxies and 46 late-type galaxies. We estimate k-corrections f…
An XMM-Newton Observation of the Local Bubble Using a Shadowing Filament in the Southern Galactic Hemisphere
Kuntz, K. D.; Henley, David B.; Shelton, Robin L.
We present an analysis of the X-ray spectrum of the Local Bubble, obtained by simultaneously analyzing spectra from two XMM-Newton pointings on and off an absorbing filament in the southern Galactic hemisphere (b~-45deg). We use the difference in the Galactic column density in these two directions to deduce the contributions of the unab…
Flow Field Evolution of a Decaying Sunspot
Liu, Chang; Denker, Carsten; Wang, Haimin +3 more
We study the evolution of the flows and horizontal proper motions in and around a decaying follower sunspot based on time sequences of two-dimensional spectroscopic observations in the visible and white-light imaging data obtained over 6 days from 2005 June 7 to 12. During this time period the sunspot decayed gradually to a pore. The spectroscopic…