[] Type Ia SN 2011ek : rapid decline of line velocity



We performed the optical photometric and spectroscopic observations of Type Ia SN 2011ek. The line velocity of SiII6355 show a rapid decline until last day. The line velocity of SiII6355 on Aug. 6 reach 15000 km/s. These observational facts indicate that SN 2011ek is classified into high-velocity SNe Ia (Benetti et al. 2005). The depth ratio of SiII5972 to SiII6355 also shows rapid decline. This supports that the ejecta rapidly expands and its temperature become high. We confirm the secondary maximum in I-band. Its luminosity is a bit lower than a typical Type Ia SN. It means that the Fe-group mass would be smaller than a typical Type Ia SN.