THE EFFECT OF THE EVOLUTION OF HD 56925 TO NEBULA NGC 2359

• Main Author: Vichesa, Yolana
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39369
• Institution: Institut Teknologi Bandung

NGC 2359 is a bubble-shaped WR nebula whose formation, structure, and evolution are influenced by the central star HD 56925. The star is a massive star that is currently observed at the Wolf Rayet stage. The evolution of the HD 56925 star is modeled using EZ-Web, a simple web-based software that can build an interior model of a single star and process the stellar evolution code from ZAMS to a stopping point. Massive stars will undergo large mass losses due to strong stellar winds. The interaction between the stellar wind and the interstellar medium produces a bubble structure. The evolution of stars causes changes in stellar wind movements in three models. Stellar wind in the Main Sequence stage has a high velocity so that it can sweep the interstellar medium and form a stellar wind bubble with a thin shell. The wind velocity decreases at the RSG stage, but its density increases because the star starts throwing masses containing heavy elements so that an interstellar medium with high metallicity is formed. At the Wolf Rayet stage, the stellar wind velocity returned and the WR ring nebula began to form. Observation of NGC 2359 shows that the main feature of the nebula is an outer ring containing the inner ring and several smaller rings inside. The outer ring has a radius of 2.40, 2.98, and 3.89 pc each measured at distances of 4, 5 and 6 kpc with an expanding mean velocity of 26 km/s. NGC 2359 as a whole is not rich in heavy elements except in the filament, this indicates that the nebula is mostly produced at the Red Supergiant and the Wolf Rayet stage.