POST-MAIN SEQUENCE EVOLUTION IN INTERMEDIATE-MASS STAR: A CASE STUDY OF CEPHEID-TYPE STARS

• Main Author: Ramadia, Defira
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/74490
• Institution: Institut Teknologi Bandung

Intermediate-mass stars undergo evolution during their lifetime, from protostars to white dwarfs. During this process, some parameters affect the evolution of stars, among other overshooting and rotation. These two parameters will affect in increasing the stellar luminosity and extending the main sequence lifetimes during the evolution. In this study, we review the effects of overshooting and rotation to the evolution of intermediate-mass stars, using Cepheid observational data. Cepheids are in the instability strip on the HR diagram. With the help of the data, we can model the evolution of Cepheid star in HR diagrams. Using Linux-based MESA with the release series r12778, stellar evolution will be carried out to review the effects of overshooting and rotation on the evolution of intermediate-mass stars with defined parameters. From the modeling, we obtain that overshooting and rotation affect the star's evolutionary tracks, resulting in changes of the luminosity, radius, and mass of the convective core during evolution. Then, by fitting the Cepheid star observational data with the model, we also obtain that our objects, Cepheid stars, are in the blue loop phases and are passing through the instability strip.