Search Publications
The hydrogen-deficient knot of the `born-again' planetary nebula Abell 58 (V605 Aql)
Barlow, M. J.; Liu, X. -W.; De Marco, O. +3 more
We have analysed deep optical spectra of the `born-again' planetary nebula Abell 58 and its hydrogen-deficient knot, surrounding V605 Aql, which underwent a nova-like eruption in 1919. Our analysis shows that the extinction towards the central knot is much higher than previously thought, with c(Hβ) = 2.0. The outer nebula is less reddened, with c(…
VLT-VIMOS integral field spectroscopy of luminous and ultraluminous infrared galaxies. I. The sample and first results
Colina, L.; Monreal-Ibero, A.; Arribas, S. +3 more
Context: (Ultra)Luminous Infrared Galaxies [(U)LIRGs] are much more numerous at cosmological distances than locally, and are likely the precursors of elliptical galaxies. Studies of the physical structure and kinematics of representative samples of these galaxies at low redshift are needed in order to understand the interrelated physical processes…
Enceladus: An estimate of heat flux and lithospheric thickness from flexurally supported topography
Neukum, Gerhard; Thomas, Peter C.; Hussmann, Hauke +4 more
We have identified flexural uplift along a rift zone of the Harran Sulci, Enceladus, using Cassini images and stereo-derived topography. On the assumption that the upraised topography is related to a flexed elastic plate, shape modeling yields an effective lithospheric thickness of 0.3 km and, combined with the strength envelope, a mechanical lith…
The connection between globular cluster systems and their host galaxy and environment: a case study of the isolated elliptical NGC 821
Spitler, Lee R.; Forbes, Duncan A.; Brodie, Jean P. +2 more
In an effort to probe the globular cluster (GC) system of an isolated elliptical galaxy, a comprehensive analysis of the NGC 821 GC system was performed. New imaging from the WIYN Mini-Mosaic imager, supplemented with Hubble Space Telescope (HST) WFPC2 images reveals a GC system similar to those found in counterpart ellipticals located in high-den…
The Puzzling White Dwarf Cooling Sequence in NGC 6791: A Simple Solution
Salaris, M.; Anderson, J.; Milone, A. P. +4 more
In this Letter we demonstrate that the puzzling bright peak in the luminosity function of the white dwarf (WD) cooling sequence of NGC 6791 can be naturally accounted for if ~34% of the observed WDs are WD+WD binary systems.
Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, whic…Decomposition of the Host Galaxies of Active Galactic Nuclei Using Hubble Space Telescope Images
Ho, Luis C.; Barth, Aaron J.; Im, Myungshin +2 more
Investigating the link between supermassive black hole and galaxy evolution requires careful measurements of the properties of the host galaxies. We perform simulations to test the reliability of a two-dimensional image-fitting technique to decompose the host galaxy and the active galactic nucleus (AGN), especially on images obtained using cameras…
Timing the Nearby Isolated Neutron Star RX J1856.5-3754
van Kerkwijk, M. H.; Kaplan, D. L.
RX J1856.5-3754 is the X-ray brightest among the nearby isolated neutron stars. Its X-ray spectrum is thermal, and is reproduced remarkably well by a blackbody, but its interpretation has remained puzzling. One reason is that the source did not exhibit pulsations, and hence a magnetic field strength—vital input to atmosphere models—could not be es…
Star Formation in the H I Bridge Between M81 and M82
Sabbi, E.; Gallagher, J. S.; Smith, L. J. +3 more
We present multiwavelength observations of stellar features in the H I tidal bridge connecting M81 and M82 in the region called Arp's loop. We identify eight young star-forming regions from Galaxy Evolution Explorer ultraviolet (UV) observations. Four of these objects are also detected at Hα. We determine the basic star-formation history of Arp's …
The depth of the convective boundary layer on Mars
Pätzold, M.; Hinson, D. P.; Häusler, B. +2 more
We are using observations obtained with Mars Express to explore the structure and dynamics of the martian lower atmosphere. We consider a series of radio occultation experiments conducted in May-August 2004, when the season on Mars was midspring of the northern hemisphere. The measurements are widely distributed in latitude and longitude, but the …
Galaxy Mergers at z gtrsim 1 in the HUDF: Evidence for a Peak in the Major Merger Rate of Massive Galaxies
Ryan, R. E., Jr.; Windhorst, R. A.; Silk, J. +1 more
We present a measurement of the galaxy merger fraction and number density from observations in the Hubble Ultra Deep Field (HUDF) for 0.5 <= z <= 2.5. We fit the combination of broadband data and slitless spectroscopy of 1308 galaxies with stellar population synthesis models to select merging systems based on a stellar mass of >=1010…