Search Publications
Quasar Lensing Caused by Clusters of Galaxies in Various Cosmological Models
Tomita, Kenji
About 33% of the observed lensed quasars have separation angles larger than 3''. To theoretically reproduce this observational fact, we investigate the statistics of quasar lensing due to clusters of galaxies, in various cosmological models including a super-horizon-scale inhomogeneous model. By calculating the expected number of lensed quasars an…
Mesures et decouvertes d'etoiles doubles effectuees a la lunette de 50cm de l'Observatoire de Nice. Measures and discoveries of visual double stars made with the 50cm refractor at the Nice Observatory.
Thorel, J. -C.
Measures and discoveries of visual double stars made at the Observatoire de la Cote d'Azur at Nice, between 1988 and 1994, with the 50cm refractor equipped with a filar micrometer and electronic recording device. The programs proposed by J. Dommanget involve the complement of the C.C.D.M. (resolving problems of identification of double stars and o…
The Brightest Stars in Nearby Galaxies IX: Comparison of Ground-Based and HST Photometry of the Brightest Stars in IC 4182
Labhardt, Lukas; Saha, Abhijit; Sandage, Allan +2 more
The distance to the Sdm dwarf galaxy IC 4182 is known from the measurements of its Cepheids made with the prerepair HST by Saha et al. [ApJ, 425,14(1994)]. IC 4182 is the parent galaxy of the type Ia supernova 1937C. Because of this it is important for calibrating the SNe Ia prime distance indicator as well as other secondary indicators. We compar…
NLTE treatment of calcium in the Monte Carlo modeling of early-time spectra of SN 1993J.
Zhang, Q.; Wang, Z. R.
NLTE treatment of calcium with five lower bound energy levels of Ca II and the ionization state of Ca III is annexed to the Monte Carlo model to improve our study on the early-time spectra of SN 1993J. This NLTE + Monte Carlo code is employed in modeling the ultraviolet and optical spectra of SN 1993J obtained simultaneously on 1993 April 15 by th…
Global astrometry with OSI.
Malbet, F.; Loiseau, S.
The Orbiting Stellar Interferometer is a proposed space-based interferometer which makes very accurate wide-angle astrometric measurements on several thousand stars. As opposed to Hipparcos, OSI does not have a "basic angle" between two separate field-of-views but three separate interferometers and a highly accurate metrology system. The questions…
Formation of the Galaxy: Clues from Globular Cluster Ages and Abundances
Fullton, Laura Kellar
In an effort to bring more data to bear on the problem of the age and formation history of the inner regions of the Milky Way, I undertook a photometric and spectroscopic study of a small sample of globular clusters within 5 kpc of the Galactic center: NGC~6723, NGC~6352 and NGC~5927. The ages and chemical compositions of these clusters provide cl…
Time Resolved Ultraviolet Spectroscopy of DQ Herculis: Eclipses and Pulsations
Anderson, Scott F.; Margon, Bruce; Downes, Ronald A. +1 more
The magnetic cataclysmic variable DQ Herculis was observed with the Faint Object Spectrograph onboard the Hubble Space Telescope (HST) over four consecutive satellite orbits, including the first observation in the UV of DQ Her through eclipse minimum. Strong emission in N V, C IV, Si IV, and He II and weak emission in O I, S III, Ni II, N IV, Si I…
Joint ULYSSES and WIND observations of a particle event in April 1995.
Simnett, G. M.; Pick, M.; Bothmer, V. +5 more
In this paper we analyze a solar particle event that was measured at two locations in the heliosphere. Ulysses was at 40°north heliolatitude and 130°west in heliolongitude from Earth while WIND was near Earth at 1 AU in the ecliptic plane. To establish the origin of the particle events, solar coronal activity is investigated. Direct observational …
Absolute magnitudes and kinematics of oxygen Mira variables.
Luri, X.; Figueras, F.; Torra, J. +1 more
A new maximum likelihood method, using apparent magnitudes, proper motions and radial velocities, has been applied to a sample of 90 Mira stars extracted from the HIPPARCOS Input Catalogue (INCA) to determine absolute magnitudes and kinematics. Using this new method three different groups of Mira stars have been identified in the sample, with diff…
Cosmic ray measurement of the 54Mn β- partial half-life
Duvernois, M. A.
In the fully stripped cosmic rays, the electron capture decay of 54Mn (τ1/2=312d) is strongly suppressed. In this situation the β- decay channel dominates; however, this half-life has never been measured in the laboratory. Some lower limits have been placed on it previously. Using the cosmic-ray data from the Ulyss…