Search Publications
Principal component analysis of two ultraviolet emission-lines in 18 active galactic nuclei
Courvoisier, T. J. -L.; Turler, M.
We apply a principal component analysis (PCA) to the spectra of each of the 18 Seyfert 1-like objects observed more than 15 times by the international ultraviolet explorer (IUE) from 1978 until the end of 1991. PCA allows us to decompose the Lyalpha and Civl\ emission-lines of each object into two components with uncorrelated variations. We find t…
Detection of fine-structure line emission from carbon-rich and oxygen-rich AGB stars by the ISO SWS
Ohnaka, K.; Tsuji, T.; Aoki, W.
We detected five forbidden lines of iron, silicon and sulfur in red giants by the ISO SWS. [FeI] 24mu m emission was detected in two carbon stars, TX Psc and WZ Cas, and [SI] 25.2mu m emission was also detected in TX Psc, while none of these emission lines were detected in an oxygen-rich giant, 30g Her. On the other hand, the [FeII] 26mu m, [SiII]…
Solid CO_2 towards NGC7538 IRS1
Leto, G.; Strazzulla, G.; Nisini, B. +2 more
We report the observation of the young infrared source NGC7538 IRS1 with the Short Wavelength Spectrometer (SWS) onboard the ISO satellite in the 2.4-45 mu m range. The spectrum exhibits several absorption features due to silicates and to molecular species frozen on the refractory dust. In particular the stretching and bending mode of solid CO_2 h…
HIPPARCOS based astrometric analysis of M 3 and M 92 fields: optical identification of X-ray and radio sources, space motions of globular clusters M 3 and M 92 and a galactic orbit of the sdB star PG 1716+426
Geffert, M.
We present positions and proper motions with respect to the Hipparcos system of stars in the fields of the globular clusters M 3 and M 92. The data were used for the optical identification of X-ray and radio sources, a new determination of the absolute proper and space motions of the globular clusters M 3 and M 92. Moreover, we derived an accurate…
Localised neutral hydrogen absorption towards the radio jet of Markarian 6
Mundell, C. G.; Holloway, A. J.; Pedlar, A. +1 more
We present 0.15'' (56 pc) resolution MERLIN observations of neutral hydrogen (Hi) lambda 21cm absorption detected towards the arcsecond-scale radio jet of the Seyfert 1.5 galaxy Markarian 6. Absorption is detected only towards a bright, compact radio feature located, in projection, 380 pc north of the likely location of the optical nucleus. Based …
The HIPPARCOS proper motion link to the extragalactic reference system using NPM and SPM
Kozhurina-Platais, V.; Lindegren, L.; Platais, I. +9 more
We describe the use of the Lick Northern Proper Motion (NPM) program and its southern-sky complement, the Yale/San Juan Southern Proper Motion (SPM) program, to determine the Hipparcos proper motion link to the extragalactic reference system defined by galaxies. In total ~ 9,100 Hipparcos stars were chosen for the NPM link solution and ~ 4,100 for…
Kinematics of the narrow-line region of NGC 1068
Dietrich, M.; Wagner, S. J.
We investigated the kinematics of the Narrow Line Region of NGC 1068. In order to study the kinematics and to determine whether the unusual broad line width can be attributed to motion of NLR clouds in a deep gravitational potential or to expanding shocks, we carried out spatially resolved echelle spectroscopy. High spectral resolution enables the…
NGC 5252 - a Liner undercover
Goncalves, A. C.; Veron, P.; Veron-Cetty, M. -P.
Ground based long slit spectroscopic observations of the nuclear region of NGC 5252, and Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) spectra of the nucleus and two bright knots located 0.36'' NE and 0.31'' SW from it, show that the nuclear region exhibits the characteristics of a Liner with exceptionally strong [O i] emission, all…
Photocentre displacement of minor planets: analysis of HIPPARCOS astrometry
Hestroffer, D.
We present a study of the phase effect (or photocentre offset) on the astrometry of minor planets. Analysis of the high precision Hipparcos observations of the largest asteroids shows the validity of the model. Minor planets Ceres, Pallas, Vesta and Iris show a brightness distribution close to the lunar scattering properties, while Juno and Hebe a…
Identification of lambda Bootis stars using IUE spectra. I. Low resolution data
Solano, E.; Paunzen, E.
An analysis of the stars included in the catalogue of lambda Bootis stars by Paunzen et al. (1997) and which also have IUE observations is presented here. Population I A-F type stars as well as field horizontal branch stars were also included in the analysis. Using line-ratios of carbon to heavier elements (Al and Ni) allows us to establish unambi…