On the system of β Lyrae.

Abstract

view Abstract Citations (9) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the system of β Lyrae. Sahade, Jorge Abstract The "classical" model of the system of p Lyrae postulates two components, a supergiant BS primary star with a mass of about So o and a secondary star, of perhaps spectral type F, smaller in radius than the BS star and with a mass of about 50 0. This model encounters difficulties which have not been removed by recent high-dispersion observations by Struve and Sahade. One of these difficulties consists in the large masses which are attributed to the components; another arises from the fact that the rotation of the primary component seems to be smaller than required by synchronization. Now, the broad emissions which are displayed by the spectrum of p Lyrae oscillate in wave length opposite in phase with respect to the lines of the BS component. This was already reported by Belopolsky (i 593) and by Curtiss (1911), who found that the amplitude of the broad Hp emissions is about 75 km/sec as against about I S~ km/sec for the BS component. Furthermore, the broad emissions in Hei and in H seem to have a relatively stronger, narrower emission superimposed upon them. This narrow feature also oscillates opposite in phase with respect to the BS component but the amplitude is smaller than that derived by Belopolsky and Curtiss for the broad Hp emissions and the value of ~ is about 130 km/sec more positive. It seems that the emissions displayed by p Lyrae arise at least partly from matter which surrounds and moves with the secondary component. If the motion suggested by the emissions is indicative of the motion of the secondary component, it would imply that the secondary star is more massive than the primary; at the same time, it must be smaller in size than the latter, as suggested by the spectrographic observations. The fact that there is streaming of matter from each of the components towards the other star suggests that the lobe of the inner contact surface must be filled; therefore, the secondary component must have a large gaseous envelope. Moreover, the difficulty of the rotational velocity of the BS component could be removed if one assumes that the star has expanded from its original size. Therefore, if we further assume that the secondary component has been the more massive since the binary system was born, we can advance tentatively the hypothesis that the system of p Lyrae is formed by a primary BS star in a late stage of its evolution, having expanded from its original size and filling now its lobe of the inner contact surface, and by a smaller, more massive secondary which has evolved faster and is already past the stage at which we are observing the BS component, being now underluminous for its mass. The streaming of matter from each star toward the other component and the expanding shell which surrounds the entire system are features of p Lyrae which do not require modification. Leuschner Observatory, University of Calsfornia, Berkeley, CaIff. REFERENCES Belopolsky, A. 1893, Mem. Soc. Spettrosc. ital. 22, 101. Curtiss, R. H. 1911, Pub. Allegheny Obs. 2, 73. Publication: The Astronomical Journal Pub Date: February 1958 DOI: 10.1086/107688 Bibcode: 1958AJ.....63...52S full text sources ADS | data products SIMBAD (1)