Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-velocity feature as the indicator of the stellar population of Type
  Ia supernovae   Although type Ia supernovae (SNe Ia) are very useful in many astrophysical
fields, their exact nature is still unclear, e.g. the progenitor and explosion
models. The high-velocity features (HVFs) in optical spectra of SNe Ia could
provide some meaningful information to constrain the nature of SNe Ia. Here, I
show strong evidence that the SNe Ia with strong CaII infrared triple (CaII
IR3) HVF around maximum brightness associate with relatively younger population
than those with weak CaII IR3 HVF, e.g. the SNe Ia with strong CaII IR3 HVF
tend to occur in late-type galaxy, or early-type galaxy with significant star
formation. In addition, using pixel statistics I find that the SNe Ia with
strong maximum-light CaII IR3 HVF show a higher degree of association with star
formation index, e.g. ${\rm H}\alpha$ or near-UV emission, than those with weak
CaII IR3 HVF. Moreover, I find that the strength of the CaII IR3 HVF is
linearly dependent on the difference of the absorption-weighted velocities
between CaII IR3 and SiII 635.5 nm absorption lines, which then is a good index
to diagnose whether or not there is a high-velocity component in the CaII IR3
absorption feature in the spectra of SNe Ia. I finally discussed the origin of
the HVFs and the constraints from our discoveries on the progenitor model of
SNe Ia.

12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph