Search Publications
Near-infrared probing of embedded structures in starburst and Seyfert galaxies
Martinet, L.; Martin, P.; Wozniak, H. +2 more
Surface photometry in the J and K' bands of 15 southern Seyfert or starburst galaxies is presented. The detailed central morphology and structural properties of these objects were analyzed by fitting ellipses to isophotes. New central peculiar structures have been identified like, for instance, three double-barred systems (ESO 215-G031;…
Blind source separation and analysis of multispectral astronomical images
Bijaoui, A.; Nuzillard, D.
Celestial sources are studied by means of multispectral analysis, for which a pixel value can be considered as a mixture of different sources. We show that the application of blind source separation methods can display interesting features, which can help astronomers to improve their description of celestial sources. Experiments were carried out o…
Variable HST guide stars (I)
Zwintz, K.; Frandsen, S.; Kuschnig, R. +4 more
We have performed time series analyses on more than 4500 sets of Hubble Space Telescope (HST) Fine Guidance Sensor (FGS) data, obtained from about 3600 guide stars in the period from August 1992 to December 1995. We discuss here a subset of 20 stars that were found to be variable at a high confidence level. This subset contains all definite variab…
A catalogue of galaxies in the HDF-South: Photometry and structural parameters
Chincarini, G.; Saracco, P.; Volonteri, M.
We describe the construction of a catalogue of galaxies in the optical field of the Hubble Deep Field South. The HDF-S observations produced WFPC2 images in U, B, V, and I, the version 1 data have been made public on 23 November 1999. The effective field of view is 4.38 arcmin2, and the 5sigma limiting magnitudes (in a FWHM aperture) ar…
AGNs with composite spectra. II. Additional data
Véron-Cetty, M. -P.; Véron, P.; Gonçalves, A. C.
In a previous paper \cite[(Véron et al. 1997)]{ver97} we presented medium resolution (3.4 Angstroms FWHM) spectroscopic observations of 15 ``transition objects'', selected for having an ambiguous location in the \cite[Veilleux & Osterbrock (1987)]{vei87} diagnostic diagrams, and showed that most of them were in fact ``composite'', this being d…
Near-infrared photometry of isolated spirals with and without an AGN. I. The data
Roth, M.; Durret, F.; González Delgado, R. M. +6 more
We present infrared imaging data in the J and K' bands obtained for 18 active spiral galaxies, together with 11 non active galaxies taken as a control sample. All of them were chosen to satisfy well defined isolation criteria so that the observed properties are not related to gravitational interaction. For each object we give: the image in the K' …
Predicted HST FOC and broad band colours for young and intermediate simple stellar populations.
Romaniello, M.; Castellani, V.; Brocato, E. +1 more
This paper presents theoretical HST and broad band colours from population synthesis models based on an homogeneous set of stellar evolutionary tracks as computed under canonical (no overshooting) assumptions, covering the range of cluster ages from t = 8 Myr to t = 5 Gyr for three different metallicities (Z=0.02, 0.006, and 0.001). Statistical fl…
Near infrared observations of quasars with extended ionized envelopes
Durret, F.; Petitjean, P.; Márquez, I.
We have observed a sample of 15 and 8 quasars with redshifts between 0.11 and 0.87 (mean value 0.38) in the J and K' bands respectively. Eleven of the quasars were previously known to be associated with extended emission line regions. After deconvolution of the image, substraction of the PSF when possible, and identification of companions with the…
Bayesian image reconstruction with space-variant noise suppression
Nunez, J.; Llacer, J.
In this paper we present a Bayesian image reconstruction algorithm with entropy prior (FMAPE) that uses a space-variant hyperparameter. The spatial variation of the hyperparameter allows different degrees of resolution in areas of different statistical characteristics, thus avoiding the large residuals resulting from algorithms that use a constant…
Surface photometry of early-type galaxies in the Hubble deep field
Fasano, G.; Filippi, M.
The detailed surface photometry of a sample of early-type galaxies in the Hubble Deep Field is presented as part of a long-term project aimed to settle strong observational constraints to the theories modelling the evolution of elliptical galaxies from the early stages. The sample has been extracted, in the V606 band, from the database …