2009/04/17 by Masayuki Yamanaka, Hiroyuki Naito, Kenzo Kinugasa +6
Physics and Astronomy · #Astro and Planetary Science #Astronomy and Astrophysical Research #Feature (linguistics) #Gamma-ray bursts and supernovae #Interstellar medium #Line (geometry) #Nucleosynthesis #Spectral line #Stellar evolution #Supernova #Type (biology) #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.1093/pasj/61.4.713
20 pages, 7 figures, (Received 2008 August 17; Accepted 2009 April 13)
arxiv created 2009/04/17 · openalex publication_date 2009/08/25 · arxiv updated 2015/05/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Abstract We present optical spectroscopic and photometric observations of Type Ia supernova (SN Ia) 2006X from 10 d before the B-band maximum to 91 d after. This object exhibits one of the highest expansion velocities ever published for SNe Ia. At its premaximum phases, the spectra show strong and broad features of intermediate-mass elements, such as Si, S, Ca, and Mg, while the Oiλ7773 line is weak. The extremely high velocities of the Si ii and S ii lines and the weak feature of the Oi line suggest that an intense nucleosynthesis might take place in the outer layers, favoring a delayed detonation model. Interestingly, the Si iiλ5972 feature is quite shallow, resulting in an unusually low depth ratio of Si iiλ5972 to Si iiλ6355, \cal R(Si ii). The low \cal R(Si ii) is usually interpreted as being a high photospheric temperature. However, the weak Si iiiλ4560 line suggests a low temperature, in contradiction with an interpretation on the low \cal R(Si ii). This could imply that the Si iiλ5972 line might be contaminated by underlying emission. We propose that \cal R(Si ii) may not be a good temperature indicator for a rapidly expanding SN Ia in the premaximum phases.