Search Publications
Low Redshift BAL QSOs in the Eigenvector 1 Context
Marziani, P.; Zamanov, R.; Braito, V. +4 more
We attempt to characterize the geometry of Broad Absorption Line (BAL) QSOs by studying a low redshift sample of 12 sources. We find that the majority of these sources are Population A quasars as defined in Sulentic et al. (2000a, broad HbetaFWHM ≤ 4000 km s(-1) ). A possible correlation between terminal velocity and absolute V magnitude suggests …
uvby - β Photoelectric Photometry of the Open Cluster α Per
Sareyan, J. -P.; Peña, J. H.
Absolute photoelectric photometry of stars in the direction of the Open Cluster α Per has been secured and is presented along with an analysis reinforced with all the available data in Strömgren uvby-β photometry compiled from the literature. Cluster membership is analyzed and the physical characteristics of the stars have been deduced. The member…
Determination of the Mass Loss Rate and the Terminal Velocity of Stellar Winds. I. Genetic Algorithm for Automatic Line Profile Fitting
Georgiev, L.; Hernández, X.
A new method for automatic fitting of Pline profiles in UV spectra of stellar winds is presented. The line source function is calculated using Sobolev's approximation and the emergent flux is obtained by exact integration of the equation of the radiation transport (similar to the SEI method described by Lamers et al. (1987)). The quality of the fi…
On the Nature of the LBV/WR Eclipsing Binary System HD 5980
Koenigsberger, G.
HD 5980 is a multiple star system in the Small Magellanic Cloud that underwent a luminous blue variable-like eruption in 1993-1994. The erupting star (star A) forms part of a close eclipsing binary whose companion's (star B) Wolf-Rayet nature has recently been questioned. The data analyzed in this paper cover the period 1979-2002, and support the …
A Revised Calibration of the MV-W(O I 7774) Relationship using Hipparcos Data: Its Application to Cepheids and Evolved Stars
Arellano Ferro, A.; Giridhar, S.; Rojo Arellano, E.
A new calibration of the MV-W(O I 7774) relationship has been calculated using better reddening and distance estimates for a sample of 27 calibrator stars of spectral types A to G, based on accurate parallaxes and proper motions from the Hipparcos and Tycho catalogues. The present calibration predicts absolute magnitude with accuracies …
CCD-Based Astrometric Measurement of Photographic Plates
Calderón, J. H.; Bustos Fierro, I. H.
We have developed a methodology for the astrometric measurement of photographic plates making use of a CCD camera. In order to measure a complete 2°x 2° plate a mosaic of 8×8 frames with 50% overlap in both coordinates was taken. The detection and centering of stellar images was performed with SExtractor, and by means of our own software triple …
Ultraviolet Spectroscopy of the Massive LMC Multiple Systems Sk-67^0m#circ;18 (Br 5) and HD 36402 (Br 31)
Koenigsberger, G.; Auer, L. H.; Moffat, A. F. J.
Following previous IUE-based spectroscopic studies of WR+O binaries in the Galaxy and in the SMC, we present a similar study of the two systems, Br 5 [O3 If^*(+O) + O8-B0 I(+OB?)] and Br 31 [WC4(+O?) + O8 I:] in the Large Magellanic Cloud. We detect wind eclipse effects in the WC4+O (P = 3.033 d) pair in Br 31 similar to, but weaker than those obs…
A Spectrographic Study of the Interacting Eclipsing Binary RY Scuti: An Episode in the Rapid Mass Loss Stage or a Protoplanetary Nebula?
Sahade, J.; West, R. M.; Skul'Sky, M. Yu.
RY Scuti, the 11-day [Fe III] eclipsing binary, has been reinvestigated on the basis of spectrographic material obtained in Chile at the European Southern Observatory, La Silla, and at the Cerro Tololo Interamerican Observatory, covering the spectral regions 3400-5150 Å and 5700-6700 Å . Ultraviolet IUE observations were also analyzed. The spectru…
Small Field CCD Astrometry with a Long Focus Reflector Telescope
Calderón, J. H.; Bustos Fierro, I. H.
We discuss the use of the block adjustment method for determining astrometric positions from a mosaic of CCD frames taken with a long focus reflector telescope. The observations cover an area of 25 arcmin × 25 arcmin around the open cluster Rup21. The source of reference positions was the Tycho-2 Catalogue. The internal error in the measured posit…
Quantitative Stellar Spectral Classification. II. Early Type Stars
García, J.; Stock, J.; Stock, M. J. +1 more
The method developed by Stock & Stock (1999) for stars of spectral types A to K to derive absolute magnitudes and intrinsic colors from the equivalent widths of absorption lines in stellar spectra is extended to B-type stars. Spectra of this type of stars for which the Hipparcos catalogue gives parallaxes with an error of less than 20% were ob…