Search Publications
Stellar parameters for Pop II A-type stars from IUE spectra and new-ODF ATLAS9 model atmospheres
Cacciari, C.; Castelli, F.
Stellar parameters for twenty-seven field horizontal branch A-type stars, a post-AGB star (BD +32 2188), and a possible cool sdB star (BD +00 0145) were obtained by fitting the whole IUE energy distributions taken from the IUE-INES archive to the ultraviolet energy distributions predicted by new-ODF ATLAS9 model atmospheres, which include the Lyma…
Variable stars in the Tycho photometric observations. I. Detection
Halbwachs, J. -L.; Soubiran, C.; Fabricius, C. +3 more
We present an original way to detect variable stars in the Tycho photometric observations. A modified Kolmogorov-Smirnov statistical test has been constructed, based on a model of most of the satellite's parameters, leading to the dispersion in the measurements. This allows us to build a treatment taking into account truncated detections and censo…
A QSO survey via optical variability and zero proper motion in the M 92 field. I. QSO candidates and selection effects
Meusinger, H.; Brunzendorf, J.
The combination of variability and proper motion constraints (VPM search) is believed to provide an unconventional yet efficient search strategy for QSOs with selection effects quite different from conventional optical QSO surveys. Previous studies in a field of high galactic latitude have shown that the VPM method is indeed an efficient search st…
Crab pulsar photometry and the signature of free precession
Vidrih, S.; Carramiñana, A.; Čadež, A. +1 more
Optical photometry for the pulsar PSR 0531+21 has been extended with new observations that strengthen evidence for a previously observed 60 s periodicity. This period is found to be increasing with time at approximately the same rate as the rotational period of the pulsar. The observed period and its time dependence fit a simple free precession mo…
Long term evolution of a non-active region sigmoid and its CME activity
Culhane, J. L.; Harra, L. K.; Matthews, S. A. +2 more
Recent studies have considered sigmoidal features in the Solar corona to possess a high probability of eruption. Unlike these studies which have focussed only on active region sigmoids, the present work centres on a large area which developed S-like morphology unconfined by a single active region. The S-like feature formed near the central meridia…
SX Phœnicis stars in the core of 47 Tucanae
Christensen-Dalsgaard, J.; Edmonds, P. D.; Bono, G. +5 more
We present new results on five of six known SX Phœnicis stars in the core of the globular cluster 47 Tucanae. We give interpretations of the light curves in the V and I bands from 8.3 days of observations with the Hubble Space Telescope near the core of 47 Tuc. The most evolved SX Phe star in the cluster is a double-mode pulsator (V2) and we deter…
Broad-line radio galaxies: Old and feeble?
van Bemmel, I.; Barthel, P.
Far-infrared photometry of broad-line radio galaxies shows this class of AGN to consist of many hot and some cool infrared emitters, with peaks in their spectral energy distributions around 25 mu m or longward of 60 mu m, respectively. Quantitative analysis indicates that this distribution relates to a substantial dispersion in the strength of the…
Eclipsing binaries with candidate CP stars. II. Parameters of the system V392 Carinae
North, P.; Debernardi, Y.
We present a detailed study of an eclipsing binary which had been classified Ap SrCrEu (Hartoog \cite{hart}) before being known as a binary. Radial velocities measured at the times of both quadratures allow us to obtain precise masses for both components, while the light curve yields the radii. The following ephemeris and fundamental parameters of…
HST and ground-based observations of the gravitational lens system Q1009-0252 A & B
Surdej, J.; Sluse, D.; Claeskens, J. -F. +2 more
In this paper, we propose a critical study of direct images and spectra obtained for the doubly imaged QSO Q1009-0252 A & B (=LBQS1009-0252 A & B). First, we report new observations with the WFPC2 onboard the Hubble Space Telescope (HST), in which the lensing galaxy is very clearly detected. We combine these with existing NICMOS observatio…
Mass segregation of different populations inside the cluster NGC 6101
Pulone, L.; Testa, V.; Marconi, G. +3 more
We have used ESO telescopes at La Silla and the Hubble Space Telescope (HST) in order to obtain accurate B, V, I CCD photometry for the stars located within 200arcsec ( =~ 2 half-mass radii, rh = 1.71arcmin ) from the center of the cluster NGC 6101. Color-Magnitude Diagrams (CMDs) extending from the red-giant tip to about 5 magnitudes b…