Strong near-infrared carbon in the Type Ia supernova iPTF13ebh

摘要: We present near-infrared (NIR) time-series spectroscopy, as well complementary ultraviolet (UV), optical, and NIR data, of the Type Ia supernova (SN Ia) iPTF13ebh, which was discovered within two days from estimated time explosion. The first spectrum taken merely 2:3 after explosion may be earliest yet obtained a SN Ia. most striking features in are several Ci lines, 1.0693 m line is strongest ever observed Interestingly, no strong optical Cii counterparts were found, even though spectroscopic series began early densely cadenced. Except at very epochs, few explosion, we show that compared to weaker appears general SNe iPTF13ebh fast decliner with m15(B) = 1:79 0:01, its absolute magnitude obeys linear part width-luminosity relation. It therefore categorized “transitional” event, on fast-declining end normal opposed subluminous/91bg-like objects. shows properties distinct both classes, bridging characteristics classes. These observations suggest composition density inner core similar 91bg-like events, it has deep-reaching carbon burning layer not more slowly declining There also substantial di erence between times inferred early-time light curve velocity evolution Siii 0.6355 line, implying long dark phase 4 days.