Kavli Affiliate: Huawei Zhang
| First 5 Authors: Han Lin, Xiaofeng Wang, Jujia Zhang, Danfeng Xiang, Tianmeng Zhang
| Summary:
We present 206 unpublished optical spectra of 104 type II supernovae obtained
by the Xinglong 2.16m telescope and Lijiang 2.4m telescope during the period
from 2011 to 2018, spanning the phases from about 1 to 200 days after the SN
explosion. The spectral line identifications, evolution of line velocities and
pseudo equivalent widths, as well as correlations between some important
spectral parameters are presented. Our sample displays a large range in
expansion velocities. For instance, the Fe~{sc ii} $5169$ velocities measured
from spectra at $tsim 50$ days after the explosion vary from ${rm 2000 km
s^{-1}}$ to ${rm 5500 km s^{-1}}$, with an average value of ${rm 3872 pm
949 km s^{-1}}$. Power-law functions can be used to fit the velocity
evolution, with the power-law exponent quantifying the velocity decline rate.
We found an anticorrelation existing between H$beta$ velocity at mid-plateau
phase and its velocity decay exponent, SNe II with higher velocities tending to
have smaller velocity decay rate. Moreover, we noticed that the velocity decay
rate inferred from the Balmer lines (i.e., H$alpha$ and H$beta$) have
moderate correlations with the ratio of absorption to emission for H$alpha$
(a/e). In our sample, two objects show possibly flash-ionized features at early
phases. Besides, we noticed that multiple high-velocity components may exist on
the blue side of hydrogen lines of SN 2013ab, possibly suggesting that these
features arise from complex line forming region. All our spectra can be found
in WISeREP and Zenodo.
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