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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2510.00135 |
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| _version_ | 1866918227050758144 |
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| author | Chen, Chun Sun, Ning-Chen Xi, Qiang Tinyanont, Samaporn Aguado, David Pérez-Fournon, Ismael Poidevin, Frédérick Maund, Justyn R. Kumar, Amit Jin, Junjie Mao, Yiming Wang, Beichuan Zhang, Yu Guo, Zhen Li, Wenxiong Rojas-Bravo, César Shen, Rong-Feng Wang, Lingzhi Wang, Ziyang Zhao, Guoying Zheng, Jie Zhu, Yinan Fernández-Nespral, David López López-Oramas, Alicia Niu, Zexi Wang, Yanan Wiersema, Klaas Liu, Jifeng |
| author_facet | Chen, Chun Sun, Ning-Chen Xi, Qiang Tinyanont, Samaporn Aguado, David Pérez-Fournon, Ismael Poidevin, Frédérick Maund, Justyn R. Kumar, Amit Jin, Junjie Mao, Yiming Wang, Beichuan Zhang, Yu Guo, Zhen Li, Wenxiong Rojas-Bravo, César Shen, Rong-Feng Wang, Lingzhi Wang, Ziyang Zhao, Guoying Zheng, Jie Zhu, Yinan Fernández-Nespral, David López López-Oramas, Alicia Niu, Zexi Wang, Yanan Wiersema, Klaas Liu, Jifeng |
| contents | SN 2025coe is a calcium-strong transient located at an extremely large projected offset $\sim$39.3 kpc from the center of its host, the nearby early-type galaxy NGC 3277 at a distance of $\sim$25.5 Mpc. In this paper, we present multi-band photometric and spectroscopic observations spanning $\sim$100 days post-discovery. Its multi-band light curves display {multiple} distinct peaks: (1) an initial peak at $t \approx 1.6$ days attributed to shock cooling emission, (2) a secondary peak of $M_{R, \, peak} \approx$ $-$15.8 mag at $t \approx 10.2$ days powered by radioactive decay, and (3) a {possible} late-time bump at $t \approx 42.8$ days likely caused by ejecta-circumstellar material/clump interaction. Spectral evolution of SN 2025coe reveals a fast transition to the nebular phase within 2 months, where it exhibits an exceptionally high [Ca II]/[O I] ratio larger than 6. Modeling of the bolometric light curve suggests an ejecta mass of $M_{\rm ej} = 0.29^{+0.14}_{-0.15} \, M_{\odot}$, a $^{56}$Ni mass of $M_{\rm ^{56}Ni} = 2.4^{+0.06}_{-0.05} \times 10^{-2} M_{\odot}$, and a progenitor envelope with mass $M_e = 1.4^{+6.9}_{-1.2} \times 10^{-3} \, M_{\odot}$ and radius $R_e = 13.5^{+64.1}_{-11.1} \, R_{\odot}$. The tidal disruption of a hybrid HeCO white dwarf (WD) by a low-mass CO WD provides a natural explanation for the low ejecta mass, the small fraction of $^{56}$Ni, and the presence of an extended, low-mass envelope. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_00135 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | SN 2025coe: A Multiple-Peaked Calcium-Strong Transient from A White-Dwarf Progenitor Chen, Chun Sun, Ning-Chen Xi, Qiang Tinyanont, Samaporn Aguado, David Pérez-Fournon, Ismael Poidevin, Frédérick Maund, Justyn R. Kumar, Amit Jin, Junjie Mao, Yiming Wang, Beichuan Zhang, Yu Guo, Zhen Li, Wenxiong Rojas-Bravo, César Shen, Rong-Feng Wang, Lingzhi Wang, Ziyang Zhao, Guoying Zheng, Jie Zhu, Yinan Fernández-Nespral, David López López-Oramas, Alicia Niu, Zexi Wang, Yanan Wiersema, Klaas Liu, Jifeng High Energy Astrophysical Phenomena Astrophysics of Galaxies High Energy Physics - Phenomenology SN 2025coe is a calcium-strong transient located at an extremely large projected offset $\sim$39.3 kpc from the center of its host, the nearby early-type galaxy NGC 3277 at a distance of $\sim$25.5 Mpc. In this paper, we present multi-band photometric and spectroscopic observations spanning $\sim$100 days post-discovery. Its multi-band light curves display {multiple} distinct peaks: (1) an initial peak at $t \approx 1.6$ days attributed to shock cooling emission, (2) a secondary peak of $M_{R, \, peak} \approx$ $-$15.8 mag at $t \approx 10.2$ days powered by radioactive decay, and (3) a {possible} late-time bump at $t \approx 42.8$ days likely caused by ejecta-circumstellar material/clump interaction. Spectral evolution of SN 2025coe reveals a fast transition to the nebular phase within 2 months, where it exhibits an exceptionally high [Ca II]/[O I] ratio larger than 6. Modeling of the bolometric light curve suggests an ejecta mass of $M_{\rm ej} = 0.29^{+0.14}_{-0.15} \, M_{\odot}$, a $^{56}$Ni mass of $M_{\rm ^{56}Ni} = 2.4^{+0.06}_{-0.05} \times 10^{-2} M_{\odot}$, and a progenitor envelope with mass $M_e = 1.4^{+6.9}_{-1.2} \times 10^{-3} \, M_{\odot}$ and radius $R_e = 13.5^{+64.1}_{-11.1} \, R_{\odot}$. The tidal disruption of a hybrid HeCO white dwarf (WD) by a low-mass CO WD provides a natural explanation for the low ejecta mass, the small fraction of $^{56}$Ni, and the presence of an extended, low-mass envelope. |
| title | SN 2025coe: A Multiple-Peaked Calcium-Strong Transient from A White-Dwarf Progenitor |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2510.00135 |