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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…
Asteroids 2867 Steins and 21 Lutetia: surface composition from far infrared observations with the Spitzer space telescope
Jorda, L.; Lamy, P. L.; Barucci, M. A. +8 more
Aims:The aim of this paper is to investigate the surface composition of the two asteroids 21 Lutetia and 2867 Steins, targets of the Rosetta space mission.
Methods: We observed the two asteroids through their full rotational periods with the Infrared Spectrograph of the Spitzer Space Telescope to investigate the surface properties. The analysi…
Thermal convection in ice-I shells of Titan and Enceladus
Showman, Adam P.; Mitri, Giuseppe
Cassini-Huygens observations have shown that Titan and Enceladus are geologically active icy satellites. Mitri and Showman [Mitri, G., Showman, A.P., 2005. Icarus 177, 447-460] and McKinnon [McKinnon, W.B., 2006. Icarus 183, 435-450] investigated the dynamics of an ice shell overlying a pure liquid-water ocean and showed that transitions from a co…
X-Ray Observations of Parsec-scale Tails behind Two Middle-Aged Pulsars
Garmire, G. P.; Pavlov, G. G.; Kargaltsev, O. +2 more
Chandra and XMM-Newton resolved extremely long tails behind two middle-aged pulsars, J1509-5850 and J1740+1000. The tail of PSR J1509-5850 is discernible up to 5.6' from the pulsar, which corresponds to the projected length l⊥ = 6.5d4 pc, where d = 4d4 kpc is the distance to the pulsar. The observed tail flux is 2 …