Anomalous extinction behaviour towards the Type Ia SN 2003cg

• Published in: Monthly notices of the Royal Astronomical Society Vol. 369; no. 4; pp. 1880 - 1900
• Main Authors: Elias-Rosa, N., Benetti, S., Cappellaro, E., Turatto, M., Mazzali, P. A., Patat, F., Meikle, W. P. S., Stehle, M., Pastorello, A., Pignata, G., Kotak, R., Harutyunyan, A., Altavilla, G., Navasardyan, H., Qiu, Y., Salvo, M., Hillebrandt, W.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 11.07.2006; Blackwell Science; Oxford University Press
• Subjects: Astronomy; dust; dust, extinction; Earth, ocean, space; Exact sciences and technology; extinction; Grain size; Spectrum analysis; Stars & galaxies; Supernovae; supernovae: general; supernovae: individual: SN 2003cg; supernovae: general; dust, extinction; supernovae: individual: SN 2003cg; Grain size; Extinction law; Infrared spectroscopy; supemovae: individual: SN 2003cg; Galaxies; Supernovae; Solar neighborhood; Infrared photometry; Color curve
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2006.10430.x

We present optical and near-infrared photometry and spectroscopy of the Type Ia SN 2003cg, which exploded in the nearby galaxy NGC 3169. The observations cover a period between −8.5 and +414 d post-maximum. SN 2003cg is a normal but highly reddened Type Ia event. Its B magnitude at maximum Bmax= 15.94 ± 0.04 and Δm15(B)obs= 1.12 ± 0.04 [Δm15(B)intrinsic= 1.25 ± 0.05]. Allowing RV to become a free parameter within the Cardelli et al. extinction law, simultaneous matches to a range of colour curves of normal SNe Ia yielded E(B−V) = 1.33 ± 0.11, and RV= 1.80 ± 0.19. While the value obtained for RV is small, such values have been invoked in the past, and may imply a grain size which is small compared with the average value for the local interstellar medium.