HIGH-VELOCITY LINE FORMING REGIONS IN THE TYPE Ia SUPERNOVA 2009ig

• Published in: The Astrophysical journal 2013-11, Vol.777 (1), p.1-15
• Main Authors: Marion, G H, VINKO, JOZSEF, Wheeler, J Craig, Foley, Ryan J, Hsiao, Eric Y, Brown, Peter J, Challis, Peter, Filippenko, Alexei V, Garnavich, Peter, Kirshner, Robert P
• Format: Article
• Language: English
• Subjects: ABSORPTION SPECTRA; ASTRONOMY; ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; Correlation; Iron; LUMINOSITY; PHOTOSPHERE; Polyvinyl fluorides; Silicon; SILICON IONS; Spectra; Spectral lines; SUPERNOVAE; Supernovas; VELOCITY; VISIBLE RADIATION
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/777/1/40

We report measurements and analysis of high-velocity (HVF) (>20,000 km s super(-1)) and photospheric absorption features in a series of spectra of the Type Ia supernova (SN) 2009ig obtained between -14 days and +13 days with respect to the time of maximum B-band luminosity (B-max). We identify lines of Si II, Si III, S II, Ca II, and Fe II that produce both HVF and photospheric-velocity (PVF) absorption features. Similarly, the S II [lambda]6355 velocity at the time of B-max is greater than "normal" for an SN Ia, but it is not extreme (v sub(Si) = 13,400 km s super(-1)). Most SNe Ia show evidence for HVF from multiple lines in spectra obtained before -10 days, and we compare the spectra of SN 2009ig to observations of other SNe. We show that each of the unusual line profiles for Si II [lambda]6355 found in early-time spectra of SNe Ia correlate to a specific phase in a common development sequence from HVF to PVF.