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Although type Ia supernovae (SNe Ia) are very useful in many astrophysicalfields, their exact nature is still unclear, e.g. the progenitor and explosionmodels. The high-velocity features (HVFs) in optical spectra of SNe Ia couldprovide some meaningful information to constrain the nature of SNe Ia. Here, Ishow strong evidence that the SNe Ia with strong CaII infrared triple (CaIIIR3) HVF around maximum brightness associate with relatively younger populationthan those with weak CaII IR3 HVF, e.g. the SNe Ia with strong CaII IR3 HVFtend to occur in late-type galaxy, or early-type galaxy with significant starformation. In addition, using pixel statistics I find that the SNe Ia withstrong maximum-light CaII IR3 HVF show a higher degree of association with starformation index, e.g. ${\rm H}\alpha$ or near-UV emission, than those with weakCaII IR3 HVF. Moreover, I find that the strength of the CaII IR3 HVF islinearly dependent on the difference of the absorption-weighted velocitiesbetween CaII IR3 and SiII 635.5 nm absorption lines, which then is a good indexto diagnose whether or not there is a high-velocity component in the CaII IR3absorption feature in the spectra of SNe Ia. I finally discussed the origin ofthe HVFs and the constraints from our discoveries on the progenitor model ofSNe Ia.

High-velocity feature as the indicator of the stellar population of Type Ia supernovae