El modelo de V453 Scorpii

El análisis de espectrogramas tomados en Córdoba, Mount Wilson y Lick, combinados con los datos disponibles de la fotometría, permite describir al sistema V453 Scorpii como formado por una estrella primaria de tipo B1 Iab y una secundaria de radio menor pero cuya masa es probablemente mayor y, en todo caso, del mismo orden de magnitud que la de otra estrella. Como se informó en el Boletín Nº4 el espectro de la estrella secundaria sólo muestra líneas de emisión, las cuales deben originarse en material que es eyectado por dicha estrella con simetría esférica. El comportamiento de los detalles espectrales sugiere la existencia de una corriente gaseosa desde la estrella B hacia la compañera (en la descripción que apareció en el Boletín Nº4 se ha deslizado un error) que puede ser la fuente de opacidad continua que afecta al espectro en ciertas fases del ciclo. El trabajo in extenso aparecerá en el número del 15 de febrero de 1965 del Astrophysical Journal.Asociación Argentina de Astronomí

El modelo de V453 Scorpii

El análisis de espectrogramas tomados en Córdoba, Mount Wilson y Lick, combinados con los datos disponibles de la fotometría, permite describir al sistema V453 Scorpii como formado por una estrella primaria de tipo B1 Iab y una secundaria de radio menor pero cuya masa es probablemente mayor y, en todo caso, del mismo orden de magnitud que la de otra estrella. Como se informó en el Boletín Nº4 el espectro de la estrella secundaria sólo muestra líneas de emisión, las cuales deben originarse en material que es eyectado por dicha estrella con simetría esférica. El comportamiento de los detalles espectrales sugiere la existencia de una corriente gaseosa desde la estrella B hacia la compañera (en la descripción que apareció en el Boletín Nº4 se ha deslizado un error) que puede ser la fuente de opacidad continua que afecta al espectro en ciertas fases del ciclo. El trabajo in extenso aparecerá en el número del 15 de febrero de 1965 del Astrophysical Journal.Asociación Argentina de Astronomí

El modelo de V453 Scorpii

El análisis de espectrogramas tomados en Córdoba, Mount Wilson y Lick, combinados con los datos disponibles de la fotometría, permite describir al sistema V453 Scorpii como formado por una estrella primaria de tipo B1 Iab y una secundaria de radio menor pero cuya masa es probablemente mayor y, en todo caso, del mismo orden de magnitud que la de otra estrella. Como se informó en el Boletín Nº4 el espectro de la estrella secundaria sólo muestra líneas de emisión, las cuales deben originarse en material que es eyectado por dicha estrella con simetría esférica. El comportamiento de los detalles espectrales sugiere la existencia de una corriente gaseosa desde la estrella B hacia la compañera (en la descripción que apareció en el Boletín Nº4 se ha deslizado un error) que puede ser la fuente de opacidad continua que afecta al espectro en ciertas fases del ciclo. El trabajo in extenso aparecerá en el número del 15 de febrero de 1965 del Astrophysical Journal.Asociación Argentina de Astronomí

Eclipsing Binaries Showing Light Time Effect

Four eclipsing binaries, which show apparent changes of period, have been studied with respect to a possible presence of the light time effect. With a least squares method we calculated new light elements of these systems, the mass function of the predicted third body, and its minimum mass. We discuss the probability of the presence of such bodies in terms of mass function, changes in radial velocity and third light in solution of light curves.Comment: 4 pages, 4 figures, 1 table, conference proceeding

Eclipsing Binaries with Possible Light-Time Effect

The period changes of six eclipsing binaries have been studied with focus on the light-time effect. With the least squares method we also calculated parameters of such an effect and properties of the unresolved body in these systems. With these results we discussed the probability of presence of such bodies in the systems with respect to possible confirmation by another method. In two systems we also suggested the hypothesis of fourth body or magnetic activity for explanation of the "second-order variability" after subtraction of the light-time effect of the third body.Comment: 4 pages, 1 figure, 2 tables, conference proceeding

Period changes in six semi-detached Algol-type binaries

Six semi-detached Algol-type binaries lacking a period analysis were chosen to test for a presence of a third body. The O-C diagrams of these binaries were analyzed with the least-squares method by using all available times of minima. Also fourteen new minima, obtained from our observations, were included in the present research. The light-time effect was adopted as a main factor for the detailed description of the long-term period changes. Third bodies were found with orbital periods from 46 up to 84 years, and eccentricities from 0.0 to 0.78 for the selected binaries. The mass functions and the minimal masses of such bodies were also calculated.Comment: 14 pages, 8 figure

Period changes in six contact binaries: WZ And, V803 Aql, DF Hya, PY Lyr, FZ Ori, and AH Tau

Six contact binaries lacking a period analysis have been chosen to search for the presence of a third body. The O-C diagrams of these binaries were analyzed with the least-squares method by using all available times of minima. Ten new minima times, obtained from our observations, were included in the present research. The Light-Time Effect was adopted for the first time as the main cause for the detailed description of the long-term period changes. Third bodies were found with orbital periods from 49 up to 100 years, and eccentricities from 0.0 to 0.56 for the selected binaries. In one case (WZ And), a fourth-body LITE variation was also applied. The mass functions and the minimal masses of such bodies were also calculated and a possible angular separation and magnitude differences were discussed for a prospective interferometric discovery of these bodies.Comment: 7 pages, 8 figures, 2009 New Astronomy 14, 12

Did the ancient egyptians record the period of the eclipsing binary Algol - the Raging one?

The eclipses in binary stars give precise information of orbital period changes. Goodricke discovered the 2.867 days period in the eclipses of Algol in the year 1783. The irregular orbital period changes of this longest known eclipsing binary continue to puzzle astronomers. The mass transfer between the two members of this binary should cause a long-term increase of the orbital period, but observations over two centuries have not confirmed this effect. Here, we present evidence indicating that the period of Algol was 2.850 days three millenia ago. For religious reasons, the ancient Egyptians have recorded this period into the Cairo Calendar, which describes the repetitive changes of the Raging one. Cairo Calendar may be the oldest preserved historical document of the discovery of a variable star.Comment: 26 pages, 5 figures, 11 table

Combining astrometry with the light-time effect: The case of VW Cep, zeta Phe and HT Vir

Three eclipsing binary systems with astrometric orbit have been studied. For a detailed analysis two circular-orbit binaries (VW Cep and HT Vir) and one binary with an eccentric orbit (zeta Phe) have been chosen. Merging together astrometry and the analysis of the times of minima, one is able to describe the orbit of such a system completely. The O-C diagrams and the astrometric orbits of the third bodies were analysed simultaneously for these three systems by the least-squares method. The introduced algorithm is useful and powerful, but also time consuming, due to many parameters which one is trying to derive. The new orbits for the third bodies in these systems were found with periods 30, 221, and 261 yr, and eccentricities 0.63, 0.37, and 0.64 for VW Cep, zeta Phe, and HT Vir, respectively. Also an independent approach to compute the distances to these systems was used. The use of this algorithm to VW Cep gave the distance d=(27.90 +/- 0.29) pc, which is in excellent agreement with the previous Hipparcos result.Comment: 10 pages, 8 figures, 3 tables, submitted to A