Supernova 2010ev: A reddened high velocity gradient type Ia supernova

Abstract

Aims: We present and study the spectroscopic and photometric evolution of the type Ia supernova (SN Ia) 2010ev. <BR /> Methods: We obtain and analyze multiband optical light curves and optical/near-infrared spectroscopy at low and medium resolution spanning -7 days to +300 days from the B-band maximum. <BR /> Results: A photometric analysis shows that SN 2010ev is a SN Ia of normal brightness with a light-curve shape of ∆m<SUB>15</SUB>(B) = 1.12 ± 0.02 and a stretch s = 0.94 ± 0.01 suffering significant reddening. From photometric and spectroscopic analysis, we deduce a color excess of E(B - V) = 0.25 ± 0.05 and a reddening law of R<SUB>v</SUB> = 1.54 ± 0.65. Spectroscopically, SN 2010ev belongs to the broad-line SN Ia group, showing stronger than average Si IIλ6355 absorption features. We also find that SN 2010ev is a high velocity gradient SN with v̇<SUB>Si</SUB> = 164 ± 7 km s<SUP>-1</SUP> d<SUP>-1</SUP>. The photometric and spectral comparison with other supernovae shows that SN 2010ev has similar colors and velocities to SN 2002bo and SN 2002dj. The analysis of the nebular spectra indicates that the [Fe II]λ7155 and [Ni II]λ7378 lines are redshifted, as expected for a high velocity gradient supernova. All these common intrinsic and extrinsic properties of the high velocity gradient (HVG) group are different from the low velocity gradient (LVG) normal SN Ia population and suggest significant variety in SN Ia explosions. <P />This paper includes data gathered with the Du Pont Telescope at Las Campanas Observatory, Chile; and the Gemini Observatory, Cerro Pachon, Chile (Gemini Program GS-2010A-Q-14). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO Programme 085.D-0577).