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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…
Variable Circumstellar Structure of Luminous Hot Stars: the Impact of Spectroscopic Long-term Campaigns
Kaufer, Andreas
The formation and evolution of galaxies.
Ellis, Richard
Galaxies represent the visible fabric of the Universe and there has been considerable progress recently in both observational and theoretical studies. The underlying goal is to understand the present-day diversity of galaxy forms, masses and luminosities. Popular models predict the bulk of the population assembled recently, in apparent agreement w…
Ultraviolet images of the gravitationally lensed quadruple quasar Q2237+0305 with the HST WFPC2
Turner, Edwin L.; Blanton, Michael; Wambsganss, Joachim
We present and analyse observations of the quadruple lensed quasar Q2237+0305, obtained with the HST WFPC2 camera in the F336W and F300W filters. 25 exposures were performed within 15h real time on 1995 November 3. On a time-scale of 3-4h, we observe no variation in component A greater than 0.02 mag. The other components remain constant over a per…
Number counts and redshift distribution of gravitational arclets as a probe of galaxy evolution
Pello, R.; Soucail, G.; Bezecourt, J.
We present a detailed model of the absolute number counts, color and redshift distributions of gravitational arclets observed in clusters of galaxies. The framework adopted for galaxy evolution is chosen to reproduce the observed number counts and redshift distribution of field galaxies. Then, a spectrophotometric evolutionary code is coupled with…
Assessment of Degradation of VIRGO Radiometers on Board SOHO
Finsterle, W.; Dewitte, S.; Anklin, M. +2 more
The Metal Absorption Systems of the Hubble Deep Field South QSO
Savaglio, Sandra
The Hubble Deep Field South (HDFS) has been recently selected, and the observations are planned for 1998 October. We present a high-resolution (FWHM ~= 14 km s^-1) spectrum of the quasar J2233-606 (z_em ~= 2.22), which is located 5.1‧ east of the HDFS. The spectrum obtained with the New Technology Telescope redward of the Lyalpha emission line cov…