Search Publications
A morphological comparison between the central region in AGN and normal galaxies using HST data
Papadakis, I. E.; Xilouris, E. M.
We study the morphology of the central region of a sample of Active Galactic Nuclei (AGN) and a ``control'' sample of normal galaxies using archival observations of the WFPC2 instrument onboard the Hubble Space Telescope (HST). We use the ellipse fitting technique in order to get a good description of the inner ``smooth'' light distribution of the…
Precision and accuracy of the orbital parameters derived from 2D & 1D space observations of visual or astrometric binaries
Pourbaix, D.
Recent investigations (e.g. Han et al. \cite{Han-2001:a}) have shown that fitting the Hipparcos observations with an orbital model when the astrometric wobble caused by the companion is below the noise level can have rather unexpected consequences. With new astrometric missions coming out within the next ten years, it is worth investigating the or…
Diagnosis of coronal magnetic field with data of Nobeyama Radio Heliograph
Nakajima, Hiroshi; Huang, Guang-Li
The expression is derived for the coronal magnetic field strength from the observations of brightness, temperature, peak frequency, spectral index, and polarization degree of solar microwave bursts. One example of solar burst on November 28, 1998 is given for the calculation of coronal magnetic field from the data of Nobeyama Radio Heliograph (NoR…
No Hexagonal Wave around Saturn's Southern Pole
Sánchez-Lavega, A.; Pérez-Hoyos, S.; French, R. G. +1 more
Hubble Space Telescope (HST) images (1997-2002) do not show a hexagonal wave in the south pole that is a counterpart of the northern one (D. A. Godfrey 1988, Icarus76, 335-356). However, a polar jet similar to that in which the north polar hexagonal wave is embedded has been discovered in the southern hemisphere. The HST images also reveal the exi…
On the source of the flaring activity in AB Doradus: the UV spectral signatures
Gómez de Castro, Ana I.
AB Dor is a young, 30-Myr-old, low-mass star with a short rotation period and strong flaring activity. In this work, a detailed analysis of the flaring activity is carried out based on ultraviolet spectral tracers of hot (T ~105 ) plasma, namely HST /GHRS profiles of the Civ[uv1] and Siiv[uv1] lines. The quiescent component has been sub…
The Interpretation of the Emission Spectra of the Seyfert 2 Galaxy NGC 7130: Determination of the Active Galactic Nucleus and Starburst Contributions
Rafanelli, P.; Radovich, M.; Contini, M. +1 more
Detailed modeling of the different regions of NGC 7130 is presented, accounting for its composite nature of an active galactic nucleus (AGN) and a starburst galaxy. Shock waves, created by stellar winds from hot massive stars and by supernova ejecta, are evident in the continuum and line spectra emitted from the clouds. Therefore, the SUMA code, w…
The signature of high-velocity gas in the spectra of NGC 4151
Prieto, M. A.; Contini, M.; Viegas, S. M.
The multiwavelength emission spectrum and associated velocity field of the Seyfert prototype NGC 4151 is modeled. Since the thirties NGC 4151 has been the subject of extensive modeling, nuclear photoionization being the basic approach considered by all authors. HST data has impressively revealed the existence of a large range of velocities (100-15…
Mrk 1014: an AGN-dominated ultraluminous infrared galaxy
Lutz, D.; Sturm, E.; Boller, Th. +1 more
In this paper we report on an XMM-Newton observation of the ultraluminous infrared QSO Mrk 1014. The X-ray observation reveals a power-law-dominated (Γ~ 2.2) spectrum with a slight excess in the soft energy range. Active galactic nucleus (AGN) and starburst emission models fit the soft excess emission equally well, however, the most plausible expl…
Hubble Space Telescope Spectroscopy of the Dwarf Nova RX Andromedae during Outburst Rise and Decline
Szkody, Paula; Sion, Edward M.; Gänsicke, Boris T. +1 more
We obtained Hubble Space Telescope far-ultraviolet spectra of the Z Cam-type dwarf nova RX And during the early rise to outburst and the decline from the same outburst. The spectral wavelength range covered was 1149-1435 Å. The rise spectrum is dominated by strong, very broad absorption lines, while the decline spectrum has strong, narrower absorp…
CCD photometric search for peculiar stars in open clusters. IV. Collinder 272, Pismis 20, Lyng\aa 14, NGC 6396 and NGC 6611
Paunzen, E.; Maitzen, H. M.; Pintado, O. I.
The time scale on which chemical peculiarity in upper main sequence stars begins is unknown. Results from the Hipparcos measurements indicate that the classical chemically peculiar (CP) stars occupy the whole area from the zero age main sequence to the terminal age main sequence (Gómez et al. \cite{Gom98}). However, Hubrig et al. (\cite{Hub00}) re…