Seeing Red (and Blue): Two Sub-Populations of Type Ia Supernovae?
We present a new analysis of the optical and near-infrared properties of a sample of 100 Type Ia supernovae (SNe Ia) observed by the Hubble Space Telescope (HST) and ground-based telescopes. We find that the optical and near-infrared colors of SNe Ia are well described by two distinct sub-populations, one with red optical colors (R-V =
0.5) and blue optical colors (R-V = -0.5). The red sub-population has a higher metallicity than the blue sub-population, as indicated by the optical depth to the Balmer series. We also find that the near-infrared colors of SNe Ia are well described by a single power law with a slope of -1.2. Our results suggest that the optical and near-infrared properties of SNe I


Abstract:

We present a new analysis of the optical and near-infrared properties of a sample of 100 Type Ia supernovae (SNe Ia) observed by the Hubble Space Telescope (HST) and ground-based telescopes. We find that the optical and near-infrared colors of SNe Ia are well described by two distinct sub-populations, one with red optical colors (R-V =
 0.5) and blue optical colors (R-V = -0.5). The red sub-population has a higher metallicity than the blue sub-population, as indicated by the optical depth to the Balmer series. We also find that the near-infrared colors of SNe Ia are well described by a single power law with a slope of -1.2. Our results suggest that the optical and near-infrared properties of SNe I