The Outermost Ejecta of Type Ia Supernovae

M. Tanaka, P. Mazzali, S. Benetti, K. Nomoto, N. Elias-Rosa, Rubina Kotak, G. Pignata, V. Stanishev, S. Hachinger

Research output: Contribution to journalArticle

70 Citations (Scopus)


The properties of the highest velocity ejecta of normal Type Ia supernovae (SNe Ia) are studied via models of very early optical spectra of six SNe. At epochs earlier than 1 week before maximum, SNe with a rapidly evolving Si II ?6355 line velocity (HVG) have a larger photospheric velocity than SNe with a slowly evolving Si II ?6355 line velocity (LVG). Since the two groups have comparable luminosities, the temperature at the photosphere is higher in LVG SNe. This explains the different overall spectral appearance of HVG and LVG SNe. However, the variation of the Ca II and Si II absorptions at the highest velocities (v>~20,000 km s-1) suggests that additional factors, such as asphericity or different abundances in the progenitor white dwarf, affect the outermost layers. The C II ?6578 line is marginally detected in three LVG SNe, suggesting that LVGs undergo less intense burning. The carbon mass fraction is small, only less than 0.01 near the photosphere, so that he mass of unburned C is only
Original languageEnglish
Pages (from-to)448-460
Number of pages13
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 10 Apr 2008

ASJC Scopus subject areas

  • Space and Planetary Science

Fingerprint Dive into the research topics of 'The Outermost Ejecta of Type Ia Supernovae'. Together they form a unique fingerprint.

  • Cite this

    Tanaka, M., Mazzali, P., Benetti, S., Nomoto, K., Elias-Rosa, N., Kotak, R., Pignata, G., Stanishev, V., & Hachinger, S. (2008). The Outermost Ejecta of Type Ia Supernovae. Astrophysical Journal, 677(1), 448-460.