THE ANALYSIS OF ? LYR SYSTEM: FROM SPECTROSCOPIC OBSERVATION AND STELLAR EVOLUTION SIMULATION

• Main Author: Prana Putra, Singgih
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/38541
• Institution: Institut Teknologi Bandung

Beta Lyrae (? Lyr) system, two brigthest stars in the Lyra constellation, is a double star system with B-type star and has emission lines in its spectrum so it is also classified as B-emission (Be) type star. The orbital inclination of ? Lyr system is 86° with current orbital period of about 12.9 days with an additional orbital period of 19 seconds/year. The mass of the primary component of the system is 2.88M? with a radius of 14.7R? and an effective temperature of 13,000 K, with a spectrum class B6-B8II. The secondary component has a mass of about 12.97M? with a radius of 6.1R? and an effective temperature of 27.989 K, as a spectrum class of B0.5V. Because the mass of the primary component is smaller than the secondary component, ? Lyr is also categorized as the Algol star system. This research is focused on two methods. The first method is the implementation of observation. Observations were conducted from May to August 2018, at the Bosscha Observatory, adjusted to the phases of the ? Lyr system. We obtained 15 spectra, then we calculated their parameters: FWHM, EW, V/R, E/C, ?Vp, rH?/r*, rHeI 5876 Å/r* and rHeI 6678 Å/r*. Radius calculation shows that these three lines are in extend process. The second method is implementing the evolution of the Lyr ? system simulation using MESA software with the MESAbinary programming code. From the simulation, we obtained the age of the binary system 2.7 x 107 years, mass and radius of the primary component M1 = 3.54M?, R1 = 16.1R?, and mass and radius of the secondary component M2 = 13.1M?, R2 = 6.85R?, and Lyr ? system is in non-conventional mass transfer epoch. The two methods show that Lyr ? system is in non-conventional mass transfer epoch and the accretion disc will disappear from the secondary component due to the cessation of mass transfer.