Search Publications
High-resolution ultraviolet spectroscopy of PG 1159-035 with HST and FUSE
Rauch, T.; Werner, K.; Kruk, J. W. +3 more
Context: PG 1159-035 is the prototype of the PG 1159 spectral class which consists of extremely hot hydrogen-deficient (pre-) white dwarfs. It is also the prototype of the GW Vir variables, which are non-radial g-mode pulsators. The study of PG 1159 stars reveals insight into stellar evolution and nucleosynthesis during AGB and post-AGB phases.
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…
Irradiation models for ULXs and fits to optical data
Copperwheat, Christopher; Cropper, Mark; Soria, Roberto +1 more
We have constructed a model which describes the optical emission from ultraluminous X-ray sources (ULXs), and have used it to constrain the parameters of seven ULX systems. Our model assumes a binary nature for ULXs, and accounts for optical emission from an X-ray-irradiated companion star and accretion disc. We apply our model to six different UL…
A Wide-Angle Tail Radio Galaxy in the COSMOS Field: Evidence for Cluster Formation
Finoguenov, A.; Kartaltepe, J. S.; Murayama, T. +19 more
We have identified a complex galaxy cluster system in the COSMOS field via a wide-angle tail (WAT) radio galaxy, consistent with the idea that WAT galaxies can be used as tracers of clusters. The WAT galaxy, CWAT-01, is coincident with an elliptical galaxy resolved in the HST ACS image. Using the COSMOS multiwavelength data set, we derive the radi…
The HELLAS2XMM survey. XI. Unveiling the nature of X-ray bright optically normal galaxies
Fiore, F.; Vignali, C.; Comastri, A. +8 more
Aims:X-ray bright optically normal galaxies (XBONGs) constitute a small but significant fraction of hard X-ray selected sources in recent Chandra and XMM-Newton surveys. Even though several possibilities were proposed to explain why a relatively luminous hard X-ray source does not leave any significant signature of its presence in terms of optical…
Evidence for a large fraction of Compton-thick quasars at high redshift
Simpson, Chris; Rawlings, Steve; Almaini, Omar +7 more
Using mid-infrared and radio selection criteria, we pre-select a sample of candidate high-redshift type 2 quasars in the Subaru XMM-Newton Deep Field (SXDF). To filter out starburst contaminants, we use a Bayesian method to fit the spectral energy distributions (SEDs) between 24-µm and the B-band, obtain photometric redshifts, and identify t…
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…
Variability in the H +3 emission of Saturn: Consequences for ionisation rates and temperature
Trafton, L. M.; Geballe, T. R.; Melin, Henrik +2 more
We present an analysis of observations of the auroral/polar regions of Saturn, carried out in 1999, 2004 and 2005, making use of the facility spectrometer, CGS4, on the United Kingdom Infrared Telescope (UKIRT), Mauna Kea, Hawaii. We obtain temperatures of 380(±70) K in 1999 and 420(±70) K in 2004. (The 2005 data has insufficient spectral resoluti…
Blending in gravitational microlensing experiments: source confusion and related systematics
Sumi, Takahiro; Mao, Shude; Smith, Martin C. +1 more
Gravitational microlensing surveys target very dense stellar fields in the local group. As a consequence, the microlensed source stars are often blended with nearby unresolved stars. The presence of `blending' is a cause of major uncertainty when determining the lensing properties of events towards the Galactic centre. After demonstrating empirica…
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…