From Nova to Type Ia Supernova -- toward sophisticated binary evolution

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K05026
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: Keio University
• Principal Investigator: KATO Mariko 慶應義塾大学, 理工学部(日吉), 教授 (50185873)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 新星 / 連星系 / 超新星

Outline of Final Research Achievements

The decay phase of nova outbursts can be followed by Kato's optically thick wind theory. Based on this method, we analyzed a number of nova light curves to determine binary parameters such as the white dwarf mass. We proposed stretched color-magnitude diagram and found common paths. Using this property we determined the distance and interstellar absorption of each nova. The recurrent nova M31N 2008-12a, a most promising candidate of Type Ia supernova, is observed in detail by our international observation team and I contributed from the theoretical side. We also calculated silicon and heavy element production during He shell flash on very massive white dwarfs that explains high velocity feature commonly observed in early phase of SN Ia explosion.

Free Research Field

天文学

Academic Significance and Societal Importance of the Research Achievements

Ia型超新星は爆発時に鉄をまきちらし宇宙の元素組成の進化に大きく寄与する天体である。また宇宙の加速膨張を検出する決め手になった天体でもある。このように重要な天体であるが、そのIa型超新星の爆発直前の天体（親天体）はいまだに確定していない。本研究は新星と回帰新星の理論的・観測的研究をおこない、連星系中の白色矮星がどのように重くなり爆発に至るかの道筋を理論的に緻密においかけて、Ia型超新星についての理解を深めるものである。