SN 2022acko: a low-luminosity SNe IIP with signs of early circumstellar interaction
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| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866914223489024000 |
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| author | Han, Lin Jujia, Zhang Xiaofeng, Wang Maokai, Hu Shuai, Zha Danfeng, Xiang Liping, Li Andrea, Reguitti Xinghan, Zhang Yongzhi, Cai Zhenyu, Wang Zeyi, Zhao Qian, Zhai Fang, Huang Weili, Lin Jinming, Bai |
| author_facet | Han, Lin Jujia, Zhang Xiaofeng, Wang Maokai, Hu Shuai, Zha Danfeng, Xiang Liping, Li Andrea, Reguitti Xinghan, Zhang Yongzhi, Cai Zhenyu, Wang Zeyi, Zhao Qian, Zhai Fang, Huang Weili, Lin Jinming, Bai |
| contents | We present optical-ultraviolet photometry and optical spectra for the type II supernova (SN) 2022acko. The spectroscopic observations span phases from $\sim$ 1.5 to $\sim$ 60 days after the explosion, while the light curve was observed up to $\sim$ 300 days. The V-band peak is $-15.5 \pm 0.3$ mag, suggesting that SN 2022acko is a low-luminosity SN II (LLSN). The overall observed properties of SN 2022acko are consistent with those produced by a lower mass progenitor ($\rm M_{ZAMS} \sim $9-10M$_{\odot}$). The spectra at $t=1.5$d and $t=2.5$d exhibit a broad emission feature peaking near 4600 Å(the ``ledge'' feature), which we interpret as blueshifted He II 4686 Ålines arising from the ionized ejecta. Moreover, a possible flash-ionized (FI) emission line of H$α$ (FWHM $\sim 1100\ \rm km \ s^{-1}$) was superposed on the broad emission component of H$α$ P-Cgyni profile in the $t=1.5$d spectrum. Assuming an ejecta velocity of $\rm 12000\ km\ s^{-1}$, the rapid disappearance of this narrow H$α$ emission line within two days suggests highly confined CSM within $\sim \rm 2\times10^{14}\, cm$. Assuming a spherically symmetric CSM, the mass loss rate within this radius is estimated to be $\rm \sim 5 \times 10^{-4} M_{\odot} \ year^{-1}$ based on our hybrid light curve model. The early ``ledge'' feature observed in SN 2022acko have also been observed in other SNe II, suggesting that early-phase circumstellar interaction (CSI) is more common than previously thought. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_23267 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | SN 2022acko: a low-luminosity SNe IIP with signs of early circumstellar interaction Han, Lin Jujia, Zhang Xiaofeng, Wang Maokai, Hu Shuai, Zha Danfeng, Xiang Liping, Li Andrea, Reguitti Xinghan, Zhang Yongzhi, Cai Zhenyu, Wang Zeyi, Zhao Qian, Zhai Fang, Huang Weili, Lin Jinming, Bai High Energy Astrophysical Phenomena We present optical-ultraviolet photometry and optical spectra for the type II supernova (SN) 2022acko. The spectroscopic observations span phases from $\sim$ 1.5 to $\sim$ 60 days after the explosion, while the light curve was observed up to $\sim$ 300 days. The V-band peak is $-15.5 \pm 0.3$ mag, suggesting that SN 2022acko is a low-luminosity SN II (LLSN). The overall observed properties of SN 2022acko are consistent with those produced by a lower mass progenitor ($\rm M_{ZAMS} \sim $9-10M$_{\odot}$). The spectra at $t=1.5$d and $t=2.5$d exhibit a broad emission feature peaking near 4600 Å(the ``ledge'' feature), which we interpret as blueshifted He II 4686 Ålines arising from the ionized ejecta. Moreover, a possible flash-ionized (FI) emission line of H$α$ (FWHM $\sim 1100\ \rm km \ s^{-1}$) was superposed on the broad emission component of H$α$ P-Cgyni profile in the $t=1.5$d spectrum. Assuming an ejecta velocity of $\rm 12000\ km\ s^{-1}$, the rapid disappearance of this narrow H$α$ emission line within two days suggests highly confined CSM within $\sim \rm 2\times10^{14}\, cm$. Assuming a spherically symmetric CSM, the mass loss rate within this radius is estimated to be $\rm \sim 5 \times 10^{-4} M_{\odot} \ year^{-1}$ based on our hybrid light curve model. The early ``ledge'' feature observed in SN 2022acko have also been observed in other SNe II, suggesting that early-phase circumstellar interaction (CSI) is more common than previously thought. |
| title | SN 2022acko: a low-luminosity SNe IIP with signs of early circumstellar interaction |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2512.23267 |