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; 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

doi:10.1086/444595

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, X. Fan, G. Folatelli, B. 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

Astronomy

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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.

Original language	English (US)
Pages (from-to)	2278-2292
Number of pages	15
Journal	Astronomical Journal
Volume	130
Issue number	5
DOIs	https://doi.org/10.1086/444595
State	Published - Nov 2005

Keywords

Supernovae: general
Supernovae: individual (SN 1999ac)

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/444595

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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, X., Folatelli, G., Frye, B., Gates, E. L., Gibbons, R., Goldhaber, 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

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, B, 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

@article{394b87411df64a6085fb147860e2c2aa,

title = "Spectroscopic observations and analysis of the unusual Type Ia SN 1999ac",

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), {\.v}, 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.",

keywords = "Supernovae: general, Supernovae: individual (SN 1999ac)",

author = "G. Garavini and G. Aldering and A. Amadon and R. Amanullah and P. Astier and G. Ballanc and G. Blanc and A. Conley and T. Dahl{\'e}n and Deustua, {S. E.} and R. Ellis and S. Fabbro and V. Fadeyev and X. Fan and G. Folatelli and B. Frye and Gates, {E. L.} and R. Gibbons and G. Goldhaber and B. Goldman and A. Goobar and Groom, {D. E.} and J. Haissinski and D. Hardin and I. Hook and Howell, {D. A.} and S. Kent and Kim, {A. G.} and Knop, {R. A.} and M. Kowalski and N. Kuznetsova and Lee, {B. C.} and C. Lidman and J. Mendez and Miller, {G. J.} and M. Moniez and M. Mouchet and A. Mour{\~a}o and H. Newberg and S. Nobili and Nugent, {P. E.} and R. Pain and O. Perdereau and S. Perlmutter and R. Quimby and N. Regnault and J. Rich and Richards, {G. T.} and P. Ruiz-Lapuente and Schaefer, {B. E.} and K. Schahmaneche and E. Smith and Spadafora, {A. L.} and V. Stanishev and Thomas, {R. C.} and Walton, {N. A.} and L. Wang and Wood-Vasey, {W. M.}",

year = "2005",

month = nov,

doi = "10.1086/444595",

language = "English (US)",

volume = "130",

pages = "2278--2292",

journal = "Astronomical Journal",

issn = "0004-6256",

publisher = "American Astronomical Society",

number = "5",

}

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, X.

AU - Folatelli, G.

AU - Frye, B.

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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UR - http://www.scopus.com/inward/citedby.url?scp=28944439249&partnerID=8YFLogxK

U2 - 10.1086/444595

DO - 10.1086/444595

M3 - Article

AN - SCOPUS:28944439249

SN - 0004-6256

VL - 130

SP - 2278

EP - 2292

JO - Astronomical Journal

JF - Astronomical Journal

IS - 5

ER -

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

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Keywords

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