Title:¬†Novae as Progenitors of Type Ia Supernovae — The Importance of Multi-wavelength Observations

A nova occurs in a binary system, in which the white dwarf (WD) accretes matter from the companion star. When a nova outburst occurs, the accreted matter is mostly blown off in a wind. In many cases, a surface layer of the WD core is dredged up and mixed into the ejecta. In recurrent novae a part of the accreted matter remains on the WD, which means that the WD grows in mass through a number of nova outbursts.  Some WD grow to near the Chandrasekhar mass and explode as type Ia supernovae (SNe Ia). Nova outbursts show rich varieties in their light curve shape, but there is a common property in the basic trend that is explained by the optically thick wind theory. We have determined the WD masses in a number of novae from comparison with theoretical light curve and multi-wavelength observation. The recurrent nova M31N 2008-12a is the most promising candidate for a SN Ia progenitor because it contains a very massive WD of about 1.38 solar masses. The modern single degenerate (SD) scenario of SNe Ia (e.g., Hachisu et al. 1999) is based on the optically thick wind theory. I will identify the candidate objects for SN Ia progenitors.