Journal article
Spectroscopic Observations and Analysis of the Unusual Type Ia SN 1999ac
The Astronomical journal, v 130(5), pp 2278-2292
01 Nov 2005
Abstract
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.
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Details
- Title
- Spectroscopic Observations and Analysis of the Unusual Type Ia SN 1999ac
- Creators
- G. Garavini - Laboratoire de Physique Nucléaire et de Hautes ÉnergiesG. AlderingA. AmadonR. AmanullahP. Astier - Laboratoire de Physique Nucléaire et de Hautes ÉnergiesC. Balland - APC - CosmologieG. BlancA. ConleyT. DahlénS.E. DeustuaR. EllisS. FabbroV. FadeyevX. FanG. FolatelliB. FryeE.L. GatesR. GibbonsG. GoldhaberB. GoldmanA. GoobarD.E. GroomJ. Haissinski - Laboratoire de l'Accélérateur LinéaireD. Hardin - Laboratoire de Physique Nucléaire et de Hautes ÉnergiesI. HookD.A. HowellS. KentA.G. KimR.A. KnopM. KowalskiN. KuznetsovaB.C. LeeC. LidmanJ. MendezG.J. MillerM. Moniez - Laboratoire de l'Accélérateur LinéaireM. Mouchet - AstroParticule et CosmologieA. MourãoH. NewbergS. Nobili - Laboratoire de Physique Nucléaire et de Hautes ÉnergiesP.E. NugentR. Pain - Laboratoire de Physique Nucléaire et de Hautes ÉnergiesO. Perdereau - Laboratoire de l'Accélérateur LinéaireS. PerlmutterR. QuimbyN. Regnault - Laboratoire de Physique Nucléaire et de Hautes ÉnergiesJ. RichG.T. RichardsP. Ruiz-LapuenteB.E. SchaeferK. Schahmaneche - Laboratoire de Physique Nucléaire et de Hautes ÉnergiesE. SmithA.L. SpadaforaV. StanishevR.C. ThomasN.A. WaltonL. WangW.M. Wood-VaseySupernova Cosmology Project
- Publication Details
- The Astronomical journal, v 130(5), pp 2278-2292
- Publisher
- American Astronomical Society
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:000232977900027
- Scopus ID
- 2-s2.0-28944439249
- Other Identifier
- 991021869218604721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Astronomy & Astrophysics