#TITLE_ALTERNATIVE#

• Main Author: IRAWAN AKBAR (NIM 10302012), EVAN
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/7844
• Institution: Institut Teknologi Bandung

Before evolving to white dwarf stage, intermediate mass stars will pass through planetary nebulae phase. Driven by stellar wind, some material will escape from the star and together with the ejected outer shell, they form nebula that surrounding the central star. The shape of nebula depends on the nature of central star, stellar winds (fast wind and superwind), and its interaction with interstellar matter. Planetary nebulae have a unique characteristic. Observationally, they have emission spectra that consist of strong forbidden lines with very weak continuum. Because of nebular expansion, the observed emission lines are Doppler shifted and seen as double. The expansion velocity is measured from the difference of wavelength between these line peaks. However, in case of compact planetary nebulae such as IC 418, the peaks are unresolved. Then, the expansion velocity is measured by applying Gaussian decomposition technique (Tamura & Shibata, 1990) and approximated model (Robinson et al., 1982). The spectrograms of IC 418 obtained in 28-29 September and 30 September-1 October 2006 using BCS attached to 45 cm-GOTO reflector at Bosscha Observatory, were reduced and calibrated using iraf. Due to the weakness of continuum, specific method was used to extract the spectrograms. This method also applied to SS 433 on PHK A-2 research, 2007 (Yuliawan et al, 2007). Data from IUE were also used to measure the terminal velocity of IC 418’s fast wind. As the results, the expansion velocity of IC 418 measured from emission lines were ranged from 9.11 km/s to 20.0 km/s due to stratification effect. While the terminal velocity of fast wind measured in CIV line was 1824.34 km/s. Based on some assumptions, using the value derived in this project and references, the kinematical age, distance, excitation class, morphological class and spatiokinematical model of IC 418 were discussed.