Spectroscopic observations and analysis of the unusual Type Ia SN 1999ac

G. Garavini, G. Aldering, A. Amadon, R. Amanullah, P. Astier, G. Ballanc, G. Blanc, A. Conley, T. Dahlén, S. E. Deustua, R. Ellis, S. Fabbro, V. Fadeyev, Xiaohui Fan, G. Folatelli, Brenda Louise Frye, E. L. Gates, R. Gibbons, G. Goldhaber, B. GoldmanA. 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

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

We present optical spectra of the peculiar Type la 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 v 10(Si II), R(Si II), v̇, and Δm 15 further underlines the unique characteristics of SN 1999ac. We find convincing evidence of C II λ6580 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.

Original languageEnglish (US)
Pages (from-to)2278-2292
Number of pages15
JournalAstronomical Journal
Volume130
Issue number5
DOIs
StatePublished - Nov 2005

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expansion
signatures
ejection
supernovae
optical spectrum
calcium
spectroscopy
iron
analysis
parameter

Keywords

  • Supernovae: general
  • Supernovae: individual (SN 1999ac)

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Garavini, G., Aldering, G., Amadon, A., Amanullah, R., Astier, P., Ballanc, G., ... Wood-Vasey, W. M. (2005). Spectroscopic observations and analysis of the unusual Type Ia SN 1999ac. Astronomical Journal, 130(5), 2278-2292. https://doi.org/10.1086/444595

Spectroscopic observations and analysis of the unusual Type Ia SN 1999ac. / Garavini, G.; Aldering, G.; Amadon, A.; Amanullah, R.; Astier, P.; Ballanc, G.; Blanc, G.; Conley, A.; Dahlén, T.; Deustua, S. E.; Ellis, R.; Fabbro, S.; Fadeyev, V.; Fan, Xiaohui; Folatelli, G.; Frye, Brenda Louise; 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.

In: Astronomical Journal, Vol. 130, No. 5, 11.2005, p. 2278-2292.

Research output: Contribution to journalArticle

Garavini, G, Aldering, G, Amadon, A, Amanullah, R, Astier, P, Ballanc, G, Blanc, G, Conley, A, Dahlén, T, Deustua, SE, Ellis, R, Fabbro, S, Fadeyev, V, Fan, X, Folatelli, G, Frye, BL, Gates, EL, Gibbons, R, Goldhaber, G, Goldman, B, Goobar, A, Groom, DE, Haissinski, J, Hardin, D, Hook, I, Howell, DA, Kent, S, Kim, AG, Knop, RA, Kowalski, M, Kuznetsova, N, Lee, BC, Lidman, C, Mendez, J, Miller, GJ, Moniez, M, Mouchet, M, Mourão, A, Newberg, H, Nobili, S, Nugent, PE, Pain, R, Perdereau, O, Perlmutter, S, Quimby, R, Regnault, N, Rich, J, Richards, GT, Ruiz-Lapuente, P, Schaefer, BE, Schahmaneche, K, Smith, E, Spadafora, AL, Stanishev, V, Thomas, RC, Walton, NA, Wang, L & Wood-Vasey, WM 2005, 'Spectroscopic observations and analysis of the unusual Type Ia SN 1999ac', Astronomical Journal, vol. 130, no. 5, pp. 2278-2292. https://doi.org/10.1086/444595
Garavini G, Aldering G, Amadon A, Amanullah R, Astier P, Ballanc G et al. Spectroscopic observations and analysis of the unusual Type Ia SN 1999ac. Astronomical Journal. 2005 Nov;130(5):2278-2292. https://doi.org/10.1086/444595
Garavini, G. ; Aldering, G. ; Amadon, A. ; Amanullah, R. ; Astier, P. ; Ballanc, G. ; Blanc, G. ; Conley, A. ; Dahlén, T. ; Deustua, S. E. ; Ellis, R. ; Fabbro, S. ; Fadeyev, V. ; Fan, Xiaohui ; Folatelli, G. ; Frye, Brenda Louise ; 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. / Spectroscopic observations and analysis of the unusual Type Ia SN 1999ac. In: Astronomical Journal. 2005 ; Vol. 130, No. 5. pp. 2278-2292.
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abstract = "We present optical spectra of the peculiar Type la 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 v 10(Si II), R(Si II), v̇, and Δm 15 further underlines the unique characteristics of SN 1999ac. We find convincing evidence of C II λ6580 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.",
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TY - JOUR

T1 - Spectroscopic observations and analysis of the unusual Type Ia SN 1999ac

AU - Garavini, G.

AU - Aldering, G.

AU - Amadon, A.

AU - Amanullah, R.

AU - Astier, P.

AU - Ballanc, G.

AU - Blanc, G.

AU - Conley, A.

AU - Dahlén, T.

AU - Deustua, S. E.

AU - Ellis, R.

AU - Fabbro, S.

AU - Fadeyev, V.

AU - Fan, Xiaohui

AU - Folatelli, G.

AU - Frye, Brenda Louise

AU - Gates, E. L.

AU - Gibbons, R.

AU - Goldhaber, G.

AU - Goldman, B.

AU - Goobar, A.

AU - Groom, D. E.

AU - Haissinski, J.

AU - Hardin, D.

AU - Hook, I.

AU - Howell, D. A.

AU - Kent, S.

AU - Kim, A. G.

AU - Knop, R. A.

AU - Kowalski, M.

AU - Kuznetsova, N.

AU - Lee, B. C.

AU - Lidman, C.

AU - Mendez, J.

AU - Miller, G. J.

AU - Moniez, M.

AU - Mouchet, M.

AU - Mourão, A.

AU - Newberg, H.

AU - Nobili, S.

AU - Nugent, P. E.

AU - Pain, R.

AU - Perdereau, O.

AU - Perlmutter, S.

AU - Quimby, R.

AU - Regnault, N.

AU - Rich, J.

AU - Richards, G. T.

AU - Ruiz-Lapuente, P.

AU - Schaefer, B. E.

AU - Schahmaneche, K.

AU - Smith, E.

AU - Spadafora, A. L.

AU - Stanishev, V.

AU - Thomas, R. C.

AU - Walton, N. A.

AU - Wang, L.

AU - Wood-Vasey, W. M.

PY - 2005/11

Y1 - 2005/11

N2 - We present optical spectra of the peculiar Type la 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 v 10(Si II), R(Si II), v̇, and Δm 15 further underlines the unique characteristics of SN 1999ac. We find convincing evidence of C II λ6580 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.

AB - We present optical spectra of the peculiar Type la 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 v 10(Si II), R(Si II), v̇, and Δm 15 further underlines the unique characteristics of SN 1999ac. We find convincing evidence of C II λ6580 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.

KW - Supernovae: general

KW - Supernovae: individual (SN 1999ac)

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