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We present an investigation of the optical spectra of 264 low-redshift (z <0.2) Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory,an untargeted transient survey. We focus on velocity and pseudo-equivalentwidth measurements of the Si II 4130, 5972, and 6355 A lines, as well those ofthe Ca II near-infrared (NIR) triplet, up to +5 days relative to the SN B-bandmaximum light. We find that a high-velocity component of the Ca II NIR tripletis needed to explain the spectrum in ~95 per cent of SNe Ia observed before -5days, decreasing to ~80 per cent at maximum. The average velocity of the Ca IIhigh-velocity component is ~8500 km/s higher than the photospheric component.We confirm previous results that SNe Ia around maximum light with a largercontribution from the high-velocity component relative to the photosphericcomponent in their Ca II NIR feature have, on average, broader light curves andlower Ca II NIR photospheric velocities. We find that these relations aredriven by both a stronger high-velocity component and a weaker contributionfrom the photospheric Ca II NIR component in broader light curve SNe Ia. Weidentify the presence of C II in very-early-time SN Ia spectra (before -10days), finding that >40 per cent of SNe Ia observed at these phases show signsof unburnt material in their spectra, and that C II features are more likely tobe found in SNe Ia having narrower light curves.

Exploring the spectral diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory