ESC observations of SN 2005cf: II. Optical Spectroscopy and the high velocity features

TL;DR

This paper presents optical spectroscopy data of SN 2005cf, analyzing high velocity features of silicon and calcium, and compares its properties with other Type Ia supernovae to understand ejecta geometry and classification.

Contribution

It provides detailed spectral observations and synthetic spectra analysis of SN 2005cf, highlighting high velocity features and their implications for supernova ejecta structure.

Findings

High velocity SiII and CaII features are present in SN 2005cf.

Synthetic spectra reveal detached high velocity SiII at 19500 km/s.

SN 2005cf belongs to the Low Velocity Gradient (LVG) group.

Abstract

The ESC-RTN optical spectroscopy data-set for SN 2005cf is presented and analyzed. The observations range from -11.6 and +77.3 days with respect to B-band maximum light. The evolution of the spectral energy distribution of SN 2005cf is characterized by the presence of high velocity SiII and CaII features. SYNOW synthetic spectra are used to investigate the ejecta geometry of silicon. Based on the synthetic spectra the SiII high velocity feature appears detached at 19500 km/s. We also securely establish the presence of such feature in SN 1990N, SN 1994D, SN 2002er and SN 2003du. On a morphological study both the CaII IR Triplet and H&K absorption lines of SN 2005cf show high velocity features centered around 24000 km/s. When compared with other Type Ia SNe based on the scheme presented in Benetti et al. 2005 SN 2005cf definitely belongs to the LVG group.