Search Publications
The nature of intermediate-redshift damped Lyα absorbers.
Deharveng, J. M.; Bergeron, J.; Le Brun, V. +1 more
We present HST/WFPC2 high-spatial resolution images in the R and B bands of the close environment of the sightlines to seven quasars which spectra show either a damped Lyα absorption line, 21cm absorption, or a very strong MgII/FeII absorption system at intermediate redshifts (0.4<=z<=1). Objects down to about 0.3", or 2.0kpc at z=0.6 (H_0_=…
Evolutionary models for metal-poor low-mass stars. Lower main sequence of globular clusters and halo field stars
Hauschildt, P. H.; Allard, F.; Baraffe, I. +1 more
We have performed evolutionary calculations of very-low-mass stars from 0.08 to 0.8 M_sunl for different metallicites from [M/H]= -2.0 to -1.0 and we have tabulated the mechanical, thermal and photometric characteristics of these models. The calculations include the most recent interior physics and improved non-grey atmosphere models. The models r…
SN IA light curves and radioactive decay
Turatto, M.; Cappellaro, E.; Benetti, S. +4 more
The absolute V light curves of 5 SNe Ia, selected to represent the known range of absolute luminosities at maximum for this class of objects, are presented. Comparison of the long term luminosity evolution shows that the differences seen at maximum persist, and actually increase with time, reinforcing the notion that intrinsic differences do exist…
Microvariability survey with the Hubble Space Telescope Fine Guidance Sensors. Exploring the instrumental properties
Kuschnig, R.; Weiss, W. W.; Gruber, R. +2 more
The suitability of the Hubble Space Telescope (HST) Fine Guidance Sensors (FGS) for a magnitude limited survey of microvariability among guide stars is investigated. The linearity, relative sensitivity, and dead-time constants of the three FGSs are determined, and the photon noise limitation of the FGS photometry is confirmed. The noise spectrum i…
HST observations of blue Straggler stars in the core of the globular cluster M 3.
Burgarella, D.; Cacciari, C.; Buonanno, R. +7 more
The core of the Galactic Globular Cluster M 3 (NGC 5272) has been observed with the WFPC2 through the filters F255W, F336W, F555W, and F814W. Using these observations along with a thorough reanalysis of earlier catalogs, we have produced a catalog of blue straggler stars (BSS) spanning the cluster. Earlier studies and the fainter part of our sampl…
Patchy intergalactic He II absorption in HE 2347-4342. II. The possible discovery of the epoch of He-reionization
Reimers, D.; Wamsteker, W.; Rodriguez-Pascual, P. +3 more
We report on observations of redshifted Heii303.8 Angstroms absorption in the high-redshift QSO HE2347-4342 (z=2.885, V=16.1) with the Goddard High Resolution Spectrograph on board HST in its low resolution mode (bigtriangleup lambda = 0.7 Angstroms). With f_λ=3.6\ 10(-15) ergcm(-2) s(-1) Angstroms(-1) at the expected position of Heii304 Angstroms…
The HIPPARCOS catalogue as a realisation of the extragalactic reference system
Zacharias, N.; Kozhurina-Platais, V.; Hemenway, P. D. +23 more
The paper describes the methods and observations by which the Hipparcos Catalogue was linked to the International Celestial Reference System (ICRS). The contributions of several groups represented in the authorship of this paper, using a variety of techniques, were synthesised in order to determine the global orientation and rotation (spin) of the…
Fundamental parameters of Wolf-Rayet stars. VI. Large Magellanic Cloud WNL stars.
Crowther, P. A.; Smith, L. J.
We present a detailed, quantitative study of late WN (WNL) stars in the LMC, based on new optical spectroscopy (AAT, MSO) and the Hillier (1990A&A...231..111H) atmospheric model. In a previous paper (Crowther et al. 1995A&A...293..172C), we showed that 4 out of the 10 known LMC Ofpe/WN9 stars should be re-classified WN9-10. We now present …
Metals in the variable DA G29-38
Koester, D.; Shipman, H. L.; Provencal, J.
We report the detection of the heavy elements Ca, Mg, Fe in the atmosphere of the variable DA white dwarf G29-38. The abundance of Ca can be understood only if accretion from interstellar matter is going on currently at a high rate. This lends support also the interpretation of the observed infrared excess as due to heated circumstellar material, …
The stellar population of the globular cluster M 3. II. CCD photometry of additional 10,000 stars.
Cacciari, C.; Carretta, E.; Buonanno, R. +5 more
We present BVI CCD photometry for more than 10,000 stars in the innermost region (0.3'<r<~4') of the globular cluster M 3. When added to the previous photographic photometry by Buonanno et al. (1994A&A...290...69B) reaching as far as r~7', this results in an homogeneous data-set including about 19,000 stars measured in this cluster, whic…