Optical and Infrared Spectroscopy of SN 1999ee and SN 1999ex

Mario Hamuy; Jose Maza; Philip A. Pinto; M. M. Phillips; Nicholas B. Suntzeff; R. D. Blum; K. A. G. Olsen; David J. Pinfield; Valentin D. Ivanov; T. Augusteijn; S. Brillant; M. Chadid; J. -G. Cuby; V. Doublier; O. R. Hainaut; E. Le Floc'h; C. Lidman; Monika G. Petr-Gotzens; E. Pompei; L. Vanzi

doi:10.1086/340968

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Optical and Infrared Spectroscopy of SN 1999ee and SN 1999ex

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Abstract

We report optical and infrared spectroscopic observations of the Type Ia SN 1999ee and the Type Ib/c SN 1999ex, both of which were hosted by the galaxy IC 5179. For SN 1999ee we obtained a continuous sequence with an unprecedented wavelength and temporal coverage beginning 9 days before maximum light and extending through day 42. Before maximum light SN 1999ee displayed a normal spectrum with a strong Si II 6355 absorption, thus showing that not all slow-declining SNe are spectroscopically peculiar at these evolutionary phases. A comparative study of the infrared spectra of SN 1999ee and other Type Ia supernovae shows that there is a remarkable homogeneity among the Branch-normal SNe Ia during their first 60 days of evolution. SN 1991bg-like objects, on the other hand, display spectroscopic peculiarities at infrared wavelengths. SN 1999ex was characterized by the lack of hydrogen lines, weak optical He I lines, and strong He I 10830,20581, thus providing an example of an intermediate case between pure Ib and Ic supernovae. We conclude therefore that SN 1999ex provides first clear evidence for a link between the Ib and Ic classes and that there is a continuous spectroscopic sequence ranging from the He deficient SNe Ic to the SNe Ib which are characterized by strong optical He I lines.

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Mario Hamuy, Jose Maza, Philip A. Pinto, M. M. Phillips, Nicholas B. Suntzeff, R. D. Blum, K. A. G. Olsen, David J. Pinfield, Valentin D. Ivanov, T. Augusteijn, S. Brillant, M. Chadid, J. -G. Cuby, V. Doublier, O. R. Hainaut, E. Le Floc'h, C. Lidman, Monika G. Petr-Gotzens, E. Pompei, L. Vanzi. 2002-03-27. Optical and Infrared Spectroscopy of SN 1999ee and SN 1999ex. https://doi.org/10.1086/340968

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