Details

Autor(en) / Beteiligte

• Garavini, G
• Aldering, G
• Amadon, A
• Amanullah, R
• Astier, P
• Balland, C
• Blanc, G
• Conley, A
• Dahlén, T
• Deustua, S. E
• Ellis, R
• Fabbro, S
• Fadeyev, V
• Fan, X
• Folatelli, G
• Frye, B
• Gates, E. L
• Gibbons, R
• Goldhaber, G
• Goldman, B
• Goobar, A
• Groom, D. E
• Haissinski, J
• Hardin, D
• Hook, I
• Howell, D. A
• Kent, S
• Kim, A. G
• Knop, R. A
• Kowalski, M
• Kuznetsova, N
• Lee, B. C
• Lidman, C
• Mendez, J
• Miller, G. J
• Moniez, M
• Mouchet, M
• Mourão, A
• Newberg, H
• Nobili, S
• Nugent, P. E
• Pain, R
• Perdereau, O
• Perlmutter, S
• Quimby, R
• Regnault, N
• Rich, J
• Richards, G. T
• Ruiz-Lapuente, P
• Schaefer, B. E
• Schahmaneche, K
• Smith, E
• Spadafora, A. L
• Stanishev, V
• Thomas, R. C
• Walton, N. A
• Wang, L
• Wood-Vasey, W. M

Titel

Spectroscopic Observations and Analysis of the Unusual Type Ia SN 1999ac

Ist Teil von

• The Astronomical journal, 2005-11, Vol.130 (5), p.2278-2292

Ort / Verlag

IOP Publishing

Erscheinungsjahr

2005

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• We present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. Prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger Si II and Ca II signatures (more characteristic of a spectroscopically normal SN). Spectra after the B-band maximum appear more normal. The expansion velocities inferred from the iron lines appear to be lower than average, whereas the expansion velocity inferred from calcium H and K are higher than average. The expansion velocities inferred from Si II are among the slowest ever observed, although SN 1999ac is not particularly dim. The analysis of the parameters v10(Si II), R(Si II), , and m15 further underlines the unique characteristics of SN 1999ac. We find convincing evidence of C II l6580 in the day -15 spectrum with ejection velocity v > 16,000 km s-1, but this signature disappears by day -9. This rapid evolution at early times highlights the importance of extremely early-time spectroscopy.