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

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

HAL : in2p3-00025098, version 1

arXiv : astro-ph/0507288

Code Bibliographique ADS : 2005AJ....130.2278G

DOI : 10.1086/444595

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Astronomical Journal 130 (2005) 2278-2292

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

G. Garavini¹, G. Aldering, A. Amadon, R. Amanullah, P. Astier¹, C. Balland^{1, 2}, G. Blanc, A. Conley, T. Dahlén, S.E. Deustua, R. Ellis, S. Fabbro, V. Fadeyev, X. Fan, G. Folatelli, B. Frye, E.L. Gates, R. Gibbons, G. Goldhaber, B. Goldman, A. Goobar, D. E. Groom, J. Haissinski³, D. Hardin¹, I. Hook, D.A. Howell, S. Kent, A.G. Kim, R.A. Knop, M. Kowalski, N. Kuznetsova, B.C. Lee, C. Lidman, J. Mendez, G.J. Miller, M. Moniez³, M. Mouchet^{2, 4}, A. Mourão, H. Newberg, S. Nobili¹, P.E. Nugent, R. Pain¹, O. Perdereau³, S. Perlmutter, R. Quimby, N. Regnault¹, J. Rich, G.T. Richards, P. Ruiz-Lapuente, B.E. Schaefer, K. Schahmaneche¹, E. Smith, A.L. Spadafora, V. Stanishev, R.C. Thomas, N.A. Walton, L. Wang, W.M. Wood-Vasey

SUPERNOVAE Collaboration(s)

(2005)

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 SiII and CaII signatures (more characteristic of a spectroscopically normal SN). Spectra after 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 SiII are among the slowest ever observed, though SN 1999ac is not particularly dim. The analysis of the parameters v_10, R(SiII), dv(SiII)/dt, and d_m15 further underlines the unique characteristics of SN 1999ac. We find convincing evidence of CII 6580 in the day -15 spectrum with ejection velocity v > 16,000 km/s, but this signature disappears by day -9. This rapid evolution at early times highlights the importance of extremely early-time spectroscopy.

1 :	LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies

2 :	APC - AstroParticule et Cosmologie

3 :	LAL - Laboratoire de l'Accélérateur Linéaire

4 :	LUTH - Laboratoire Univers et Théories

équipe(s) de recherche : APC - Cosmologie et Gravitation

Thème(s)

Planète et Univers/Astrophysique

Physique/Astrophysique/Cosmologie et astrophysique extra-galactique

Planète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactique

Mot(s)-clé(s) : supernovae: general – supernovae: individual (SN 1999ac)

Lien vers le texte intégral :

http://fr.arXiv.org/abs/astro-ph/0507288


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Soumis le : Mardi 22 Novembre 2005, 09:46:38
Dernière modification le : Vendredi 10 Août 2012, 11:59:52