Search Publications
Evolution of the near-infrared in rich galaxy clusters
Mobasher, Bahram; Trentham, Neil
We present the K-band (2.2 µm) luminosity functions (LFs) of the X-ray-luminous clusters MS1054-0321 (z=0.823), MS0451-0305 (z=0.55), Abell 963 (z=0.206), Abell 665 (z=0.182) and Abell 1795 (z=0.063) down to absolute magnitudes M_K=-20. Our measurements probe fainter absolute magnitudes than do any previous studies of the near-infrared LFs o…
Deep Hubble Space Telescope Galaxy and Pair Counts as Tests of Merger History
Keel, William C.; Wu, Wentao
We consider the use of counts of faint galaxy pairs as tests of the role of merging in galaxy evolution, using both simulations and Hubble Space Telescope (HST) data in comparison with models incorporating a range in the evolution of merger rate. Artificial data, including simulation of the surface-brightness selection effects implicit in HST imag…
Mid-IR mapping of the region of N 4 in the Large Magellanic Cloud with ISOCAM
Boulanger, F.; Heydari-Malayeri, M.; Sauvage, M. +9 more
We present images of the N 4 region in the Large Magellanic Cloud obtained with ISOCAM on board ISO through broad band filters centered at 6.75 and 15 mu m. Far from the three H i I regions contained in the map, the emission at both wavelengths is due to the Unidentified Infrared Bands and associated continuum and originates in the external layers…
Stellar Populations and Variable Stars in the Core of the Globular Cluster M5
Drissen, Laurent; Shara, Michael M.
We report the discovery of a variable blue straggler in the core of the globular cluster M5, based on a 12 hr-long series of images obtained with the Planetary Camera aboard the Hubble Space Telescope. In addition, we present the light curves of 28 previously unknown or poorly studied large-amplitude variable stars (all but one are RR Lyrae stars)…
An alternative explanation of the EUV spectrum of the white dwarf G191-B2B invoking a stratified H+He envelope including heavier elements
Barstow, M. A.; Hubeny, I.
Only recently has it been possible to find an effective temperature and composition for the hot DA white dwarf G191-B2B which can consistently match the optical, far-UV and EUV data simultaneously, by using new non-LTE model calculations that include the effects of line blanketing from more than 9 million (mainly Fe and Ni) transitions. However, t…
Dark haloes of spiral galaxies: ISO photometry
Gilmore, Gerard; Unavane, M.
We exclude hydrogen-burning stars, of any mass above the hydrogen-burning limit and any metallicity, as significant contributors to the massive haloes deduced from rotation curves to dominate the outer parts of spiral galaxies. We present and analyse images of four nearly edge-on bulgeless spiral galaxies (UGC 711, NGC 2915, UGC 12426, UGC 1459) o…
The Arcetri spectral code for thin plasmas
Landini, M.; Landi, E.
The Arcetri spectral code allows to evaluate the spectrum of the radiation emitted by hot and optically thin plasmas in the spectral range 1 - 2000 Angstroms. The database has been updated including atomic data and radiative and collisional rates to calculate level population and line emissivities for a number of ions of the minor elements; a crit…
Hubble constant from sosie galaxies and HIPPARCOS geometrical calibration
Paturel, G.; Bottinelli, L.; Gouguenheim, L. +5 more
New distances, larger than previous ones, have been obtained for M 31 and M 81 based on the geometrical zero-point of the Cepheid Period-luminosity relation provided by the HIPPARCOS satellite. By combining them with independent determinations we define reasonable ranges for the distances of these important calibrating galaxies. On this basis, we …
First VLA Observations of Nonthermal Metric Bursts Associated with Coronal Mass Ejections Detected by the Solar and Heliospheric Observatory
St. Cyr, O. C.; Thompson, B. J.; Willson, R. F. +2 more
We present the first observations of nonthermal decimetric burst emission of the Sun using the new 400 cm (74 MHz) system at the VLA. Our VLA observations were carried out in collaboration with the Large Angle Spectroscopic Coronagraph (LASCO) and the Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory space…
Deuterium Observations in the Galaxy
Ferlet, R.; Vidal-Madjar, A.; Lemoine, M.
An accurate measurement of the primordial value of D/H would provide one of the best tests of nucleosynthesis models for the early Universe and the baryon density. Such evaluations have been traditionally made using present estimations of the deuterium abundance in the interstellar medium, extrapolated backwards in time with the use of galactic ev…