Search Publications
Large-scale dynamics and polarities of magnetic structures
Meunier, N.
A large data set of MDI magnetograms is studied in order to analyse the dependence of the global dynamics of magnetic structures on their polarity. Two complementary techniques (feature tracking and correlation tracking) are used to determine the differential rotation and meridional circulation. A faster rotation of leading polarity structures is …
Accurate photometric light curves of the lensed components of Q2237+0305 derived with an optimal image subtraction technique: Evidence for microlensing in image A
Surdej, J.; Libbrecht, C.; Moreau, O. +1 more
Using an optimal image subtraction technique, we have derived the V and R light curves of the four lensed QSO components of Q2237+0305 from the monitoring CCD frames obtained by the GLITP collaboration with the 2.6 m NOT telescope in 1999/2000 (Alcalde et al. 2002). We give here a detailed account of the data reduction and analysis and of the erro…
High Excitation ISM and Gas
Peeters, Els; Rodríguez-Fernández, Nemesio J.; Martín-Hernández, Nieves Leticia +1 more
An overview is given of ISO results on regions of high excitation ISM and gas, i.e. H II regions, the Galactic Centre and Supernova Remnants. IR emission due to fine-structure lines, molecular hydrogen, silicates, polycyclic aromatic hydrocarbons and dust are summarised, their diagnostic capabilities illustrated and their implications highlighted.
Outbursts on normal stars. FH Leo misclassified as a novalike variable
Santos, N. C.; Schmidtobreick, L.; Israelian, G. +1 more
We present high resolution spectroscopy of the common proper motion system FH Leo (components HD 96273 and BD+07 2411B), which has been classified as a novalike variable due to an outburst observed by Hipparcos, and we present and review the available photometry. We show from our spectra that neither star can possibly be a cataclysmic variable, in…
Dust Morphology of Hidden Broad-Line Region and Non-Hidden Broad-Line Region Seyfert 2 Galaxies
Hwang, Chorng-Yuan; Yu, Po-Chieh
We investigate the nuclear dust properties of hidden broad-line region (HBLR) and non-HBLR Seyfert 2 galaxies. Optical images obtained from the Hubble Space Telescope for a selected sample of HBLR and non-HBLR Seyfert 2 galaxies are fitted with the Galfit package to probe the inner structures of these galaxies within the central 1 kpc regions. Mos…
The Discovery of Oxygen-rich Chromospheres in Two Massive DQ White Dwarfs
Provencal, J. L.; Shipman, H. L.; MacDonald, James
We present HST observations of the massive DQ white dwarfs G227-5 and G35-26 in which we find the first clear evidence of chromospheric activity in cool field white dwarfs. The chromospheric spectra, obtained over a very narrow wavelength range, show lines of the usually expected species O I, N I, C II, and possibly Si III and Mg II. The O I/C II …
Spin-resolved Far-Ultraviolet Observations of the Magnetic White Dwarf in YY Draconis
Szkody, Paula; Sion, Edward M.; Hoard, D. W. +1 more
We observed the intermediate polar YY Draconis with the Far Ultraviolet Spectroscopic Explorer (FUSE), yielding an average far-UV spectrum, as well as spectra and spectrophotometric light curves resolved on the spin phase of the white dwarf in this system. We utilized the BINSYN software suite to calculate model spectra based on a simple system mo…
Systematic motions in the galactic plane found in the Hipparcos catalogue using Herschel's Method
Vieira, K.; Abad, C.
Two motions in the galactic plane have been detected and characterized, based on the determination of a common systematic component in Hipparcos catalogue proper motions. The procedure is based only on positions, proper motions and parallaxes, plus a special algorithm which is able to reveal systematic trends. Our results come from two stellar sam…
Cosmic Shear from STIS pure parallels. III. Analysis of Cycle 9 pure parallels
Fosbury, R. A. E.; Schneider, P.; Erben, T. +4 more
Following the detection of a cosmic shear signal at the 30'' scale using archival parallel data from the STIS CCD camera onboard HST in the previous paper of this series, we analyzed a larger data set obtained from an HST GO pure parallel program. Although this data set is considerably larger than the one analyzed previously, we do not obtain a si…
Large-scale velocity fluctuations in polar solar wind
Bavassano, B.; Bruno, R.; D'Amicis, R.
The 3-D structure of the solar wind varies dramatically along the Sun's activity cycle. In the present paper we focus on some properties of the polar solar wind. This is a fast, teneous, and steady flow (as compared to low-latitude conditions) that fills the high-latitude heliosphere at low solar activity. The polar wind has been extensively inves…