SN 2021hpr: A Normal Type Ia Supernova Showing Excess Emission in the Early Rising Phase
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arXiv
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| Natura: | Preprint |
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2025
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| author | Iskandar, Abdusamatjan Wang, Xiaofeng Esamdin, Ali Zeng, Xiangyun Pellegrino, Craig Yan, Shengyu Liu, Jialian Filippenko, Alexei V. Howell, D. Andrew McCully, Curtis Brink, Thomas G. Hu, Maokai Yang, Yi Zheng, WeiKang Lü, Guoliang Zhang, Jujia Song, CuiYing Huang, RuiFeng Amaro, Rachael Bai, Chunhai Dettman, Kyle G. Galbany, Lluís Hiramatsu, Daichi Azalee, Bostroem K. Itagaki, Koichi Jha, Saurabh W. Ma, Shuguo Sand, David Andrews, Jennifer E. Jencson, Jacob Milne, Peter Pearson, Jeniveve Shrestha, Manisha Smith, Nathan Könyves-Tóth, Réka Wyatt, Samuel Zhang, Xuan Yaqup, Shahidin Wang, Letian Zhang, Mengfan |
| author_facet | Iskandar, Abdusamatjan Wang, Xiaofeng Esamdin, Ali Zeng, Xiangyun Pellegrino, Craig Yan, Shengyu Liu, Jialian Filippenko, Alexei V. Howell, D. Andrew McCully, Curtis Brink, Thomas G. Hu, Maokai Yang, Yi Zheng, WeiKang Lü, Guoliang Zhang, Jujia Song, CuiYing Huang, RuiFeng Amaro, Rachael Bai, Chunhai Dettman, Kyle G. Galbany, Lluís Hiramatsu, Daichi Azalee, Bostroem K. Itagaki, Koichi Jha, Saurabh W. Ma, Shuguo Sand, David Andrews, Jennifer E. Jencson, Jacob Milne, Peter Pearson, Jeniveve Shrestha, Manisha Smith, Nathan Könyves-Tóth, Réka Wyatt, Samuel Zhang, Xuan Yaqup, Shahidin Wang, Letian Zhang, Mengfan |
| contents | We present extensive optical observations of a nearby Type Ia supernova (SN Ia), SN 2021hpr, located in the spiral galaxy NGC 3147 at a distance of $\sim$ 45 Mpc. Our observations cover a phase within $\sim 1-2$ days to $\sim 290$ days after the explosion. SN 2021hpr is found to be a spectroscopically normal SN Ia, with an absolute B-band peak magnitude of $M_{max}(B) \approx -19.16 \pm 0.14$ mag and a post-peak decline rate of $Δm_{15}(B)= 1.00 \pm 0.01 $ mag. Early-time light curves showed a $\sim 7.0 \%$ excess emission compared to a homogeneously expanding fireball model, likely due to SN ejecta interacting with a companion or immediate circumstellar matter. The optical spectra of SN 2021hpr are overall similar to those of normal SNe Ia, but characterized by prominent detached high-velocity features (HVFs) of Si {\sc ii} and Ca {\sc ii} in the early phase. After examining a small sample of well-observed normal SNe Ia, we find that the HVFs are likely common for the subgroup with early-excess emission. The association of early bump feature with the HVFs could be attributed to density or abundance enhancement at the outer layer of the exploding star, likely as a result of interactions with companion$/$CSM or experiencing more complete burning. Nevertheless, the redshifted Fe {\sc ii} and Ni {\sc ii} lines in the nebular-phase spectra of SN 2021hpr, contrary to the blueshift trend seen in other SNe Ia showing early bump features, indicate its peculiarity in the explosion that remains to be understood. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_02257 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | SN 2021hpr: A Normal Type Ia Supernova Showing Excess Emission in the Early Rising Phase Iskandar, Abdusamatjan Wang, Xiaofeng Esamdin, Ali Zeng, Xiangyun Pellegrino, Craig Yan, Shengyu Liu, Jialian Filippenko, Alexei V. Howell, D. Andrew McCully, Curtis Brink, Thomas G. Hu, Maokai Yang, Yi Zheng, WeiKang Lü, Guoliang Zhang, Jujia Song, CuiYing Huang, RuiFeng Amaro, Rachael Bai, Chunhai Dettman, Kyle G. Galbany, Lluís Hiramatsu, Daichi Azalee, Bostroem K. Itagaki, Koichi Jha, Saurabh W. Ma, Shuguo Sand, David Andrews, Jennifer E. Jencson, Jacob Milne, Peter Pearson, Jeniveve Shrestha, Manisha Smith, Nathan Könyves-Tóth, Réka Wyatt, Samuel Zhang, Xuan Yaqup, Shahidin Wang, Letian Zhang, Mengfan High Energy Astrophysical Phenomena Astrophysics of Galaxies Solar and Stellar Astrophysics We present extensive optical observations of a nearby Type Ia supernova (SN Ia), SN 2021hpr, located in the spiral galaxy NGC 3147 at a distance of $\sim$ 45 Mpc. Our observations cover a phase within $\sim 1-2$ days to $\sim 290$ days after the explosion. SN 2021hpr is found to be a spectroscopically normal SN Ia, with an absolute B-band peak magnitude of $M_{max}(B) \approx -19.16 \pm 0.14$ mag and a post-peak decline rate of $Δm_{15}(B)= 1.00 \pm 0.01 $ mag. Early-time light curves showed a $\sim 7.0 \%$ excess emission compared to a homogeneously expanding fireball model, likely due to SN ejecta interacting with a companion or immediate circumstellar matter. The optical spectra of SN 2021hpr are overall similar to those of normal SNe Ia, but characterized by prominent detached high-velocity features (HVFs) of Si {\sc ii} and Ca {\sc ii} in the early phase. After examining a small sample of well-observed normal SNe Ia, we find that the HVFs are likely common for the subgroup with early-excess emission. The association of early bump feature with the HVFs could be attributed to density or abundance enhancement at the outer layer of the exploding star, likely as a result of interactions with companion$/$CSM or experiencing more complete burning. Nevertheless, the redshifted Fe {\sc ii} and Ni {\sc ii} lines in the nebular-phase spectra of SN 2021hpr, contrary to the blueshift trend seen in other SNe Ia showing early bump features, indicate its peculiarity in the explosion that remains to be understood. |
| title | SN 2021hpr: A Normal Type Ia Supernova Showing Excess Emission in the Early Rising Phase |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2503.02257 |