[] 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.

[] Optical Transient in UGC 2773 : update


We update the light curves of the optical transient in UGC 2773.


[] Type Ia SN 2011ek : high-velocity features and a possible CII line.

f:id:kanataobslog:20110814173333p:image f:id:kanataobslog:20110814173332p:image

We have observed Type Ia SN 2011ek since 2011 Aug 6. This SN was discovered on 2011 Aug 4.7 at the nearby galaxy NGC 918 by K. Itagaki. We performed follow-up spectroscopic observations of this SN. This SN was identified as high-velocity Type Ia SN at more 10 days before maximum-light (CBET 2785, 2786). The spectra exhibit high-velocity SiII 5972, 6355 and CaII IR triplet features. The blueshifts of these absorption lines are calculated to be 15000 km/s at Aug 6. These features also exhibit the broader absorption lines than low-velocity SNe Ia. These features are common to high-velocity Type Ia SNe (Benetti et al. 2005, Branch et al. 2006). We also possibly identify the very weak carbon absorption line at 6250A. They may be common features in some Type Ia SNe (Parrent et al. 2011). It may be a signature of the unburnt material of the white dwarf. We also performed phometric observations. The rising time seems to be faster than low-velocity SNe Ia (Ganeshalingam et al .2011). The luminosity still does not reach the maximum-light in B-band. We will observations of this SN.


[] Type Ia SN 2011B : update


We update the light curve of Type Ia SN 2011B.