Stéphane Collin

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Results of a long-term monitoring (10 years) of the broad line and continuum fluxes of three Active Galactic Nuclei (AGN), 3C 390.3, NGC 4151, and NGC 5548, are presented. We analyze the Hα and Hβ profile variations during the monitoring period and study different details (as bumps, absorption bands) which can indicate structural changes in the Broad Line(More)
Context. Many active galactic nuclei exhibit X-ray features typical of the highly ionized gas called " Warm Absorber " (WA). Such a material appears to be stratified, displaying zones of different density, temperature, and ionization. In this paper, we investigate the possibility of modelling the WA gas in NGC 3783 as a single medium in total pressure(More)
We have monitored the AGN 3C 390.3 between 1995 and 2000. A historical B-Band light curve dating back to 1966, shows a large increase in brightness during 1970 – 1971, followed by a gradual decrease down to a minimum in 1982. During the 1995–2000 lapse the broad Hβ emission and the continuum flux varied by a factor of ≈ 3. Two large amplitude outbursts, of(More)
This paper presents the low cost electrodeposition of a transparent and conductive chlorine doped ZnO layer with performances comparable to that produced by standard vacuum processes. First, an in-depth study of the defect physics by ab-initio calculation shows that chlorine is one of the best candidates to dope the ZnO. This result is experimentally(More)
Aims. Results of a long-term spectral monitoring of the active galactic nucleus of NGC 4151 are presented (11 years, from 1996 to 2006). Methods. High quality spectra (S/N> 50 in the continuum near Hα and Hβ) were obtained in the spectral range ∼ 4000 to 7500 Å, with a resolution between 5 and 15 Å, using the 6-m and the 1-m SAO's telescopes (Russia), the(More)
Between 1996 and 2002, we have carried out a spectral monitoring program for the Seyfert galaxy NGC 5548 with the 6 m and 1 m telescopes of SAO (Russia) and with the 2.1 m telescope of Guillermo Haro Observatory (GHO) at Cananea, México. High quality spectra with S/N> 50 in the continuum near Hα and Hβ were obtained, covering the spectral range ∼(4000 –(More)
We present results of the photoionization code IRIS, which calculates the spectrum emitted by the Warm Absorber (WA) in Seyfert 1 galaxies for a large grid of parameters (density, column density, ionization parameter...). We show that in Seyfert 1s, coronal lines ([Fe x], [Fe xi], [Fe xiv]...), whose emission region shares common characteristics with the(More)
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