TY - JOUR
T1 - The very young type Ia supernova 2012cg
T2 - Discovery and early-time follow-up observations
AU - Silverman, Jeffrey M.
AU - Ganeshalingam, Mohan
AU - Cenko, S. Bradley
AU - Filippenko, Alexei V.
AU - Li, Weidong
AU - Barth, Aaron J.
AU - Carson, Daniel J.
AU - Childress, Michael
AU - Clubb, Kelsey I.
AU - Cucchiara, Antonino
AU - Graham, Melissa L.
AU - Marion, G. H.
AU - Nguyen, My L.
AU - Pei, Liuyi
AU - Tucker, Brad E.
AU - Vinko, Jozsef
AU - Wheeler, J. Craig
AU - Worseck, Gabor
PY - 2012
Y1 - 2012
N2 - On 2012 May 17.2 UT, only 1.5 ± 0.2 days after explosion, we discovered SN 2012cg, a Type Ia supernova (SN Ia) in NGC4424 (d ≈ 15Mpc). As a result of the newly modified strategy employed by the Lick Observatory Supernova Search, a sequence of filtered images was obtained starting 161s after discovery. Utilizing recent models describing the interaction of supernova (SN) ejecta with a companion star, we rule out a ∼ 1 M ⊙ companion for half of all viewing angles and a red-giant companion for nearly all orientations. SN 2012cg reached a B-band maximum of 12.09 ± 0.02 mag on 2012 June 2.0 and took ∼17.3days from explosion to reach this, typical for SNe Ia. Our pre-maximum-brightness photometry shows a narrower-than-average B-band light curve for SN 2012cg, though slightly overluminous at maximum brightness and with normal color evolution (including some of the earliest SN Ia filtered photometry ever obtained). Spectral fits to SN 2012cg reveal ions typically found in SNe Ia at early times, with expansion velocities ≳14,000kms-1 at 2.5days past explosion. Absorption from C II is detected early, as well as high-velocity components of both Si II λ6355 and Ca II. Our last spectrum (13.5days past explosion) resembles that of the somewhat peculiar SN Ia 1999aa. This suggests that SN 2012cg will have a slower-than-average declining light curve, which may be surprising given the faster-than-average rising light curve.
AB - On 2012 May 17.2 UT, only 1.5 ± 0.2 days after explosion, we discovered SN 2012cg, a Type Ia supernova (SN Ia) in NGC4424 (d ≈ 15Mpc). As a result of the newly modified strategy employed by the Lick Observatory Supernova Search, a sequence of filtered images was obtained starting 161s after discovery. Utilizing recent models describing the interaction of supernova (SN) ejecta with a companion star, we rule out a ∼ 1 M ⊙ companion for half of all viewing angles and a red-giant companion for nearly all orientations. SN 2012cg reached a B-band maximum of 12.09 ± 0.02 mag on 2012 June 2.0 and took ∼17.3days from explosion to reach this, typical for SNe Ia. Our pre-maximum-brightness photometry shows a narrower-than-average B-band light curve for SN 2012cg, though slightly overluminous at maximum brightness and with normal color evolution (including some of the earliest SN Ia filtered photometry ever obtained). Spectral fits to SN 2012cg reveal ions typically found in SNe Ia at early times, with expansion velocities ≳14,000kms-1 at 2.5days past explosion. Absorption from C II is detected early, as well as high-velocity components of both Si II λ6355 and Ca II. Our last spectrum (13.5days past explosion) resembles that of the somewhat peculiar SN Ia 1999aa. This suggests that SN 2012cg will have a slower-than-average declining light curve, which may be surprising given the faster-than-average rising light curve.
KW - supernovae: general
KW - supernovae: individual: SN 2012cg
UR - http://www.scopus.com/inward/record.url?scp=84865159847&partnerID=8YFLogxK
U2 - 10.1088/2041-8205/756/1/L7
DO - 10.1088/2041-8205/756/1/L7
M3 - Article
SN - 2041-8205
VL - 756
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L7
ER -