TY - JOUR
T1 - SN 2025coe: A Multiple-peaked Calcium-strong Transient from a White-dwarf Progenitor
AU - Chen, Chun
AU - Sun, Ning-Chen
AU - Xi, Qiang
AU - Tinyanont, Samaporn
AU - Aguado, David
AU - Pérez-Fournon, Ismael
AU - Poidevin, Frédérick
AU - Maund, Justyn R.
AU - Kumar, Amit
AU - Jin, Junjie
AU - Mao, Yiming
AU - Wang, Beichuan
AU - Zhang, Yu
AU - Guo, Zhen
AU - Li, Wenxiong
AU - Rojas-Bravo, César
AU - Shen, Rong-Feng
AU - Wang, Lingzhi
AU - Wang, Ziyang
AU - Zhao, Guoying
AU - Zheng, Jie
AU - Zhu, Yinan
AU - López Fernández-Nespral, David
AU - López-Oramas, Alicia
AU - Niu, Zexi
AU - Wang, Yanan
AU - Wiersema, Klaas
AU - Liu, Jifeng
PY - 2026/1/14
Y1 - 2026/1/14
N2 - SN 2025coe is a calcium-strong transient located at an extremely large projected offset ∼39.3 kpc from the center of its host, the nearby early-type galaxy NGC 3277 at a distance of ∼25.5 Mpc. In this paper, we present multiband photometric and spectroscopic observations spanning ∼100 days postdiscovery. Its multiband light curves display multiple distinct peaks: (1) an initial peak at t ≍ 1.6 day attributed to shock cooling emission, (2) a secondary peak of MR, peak ≍ −15.8 mag at t ≍ 10.2 days powered by radioactive decay, and (3) a possible late-time bump at t ≍ 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 Mej=0.29−0.15+0.14M⊙, a 56Ni mass of M56Ni=2.4−0.05+0.06×10−2M⊙, and a progenitor envelope with mass Me=1.4−1.2+6.9×10−3M⊙ and radius Re=13.5−11.1+64.1R⊙. 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 56Ni, and the presence of an extended, low-mass envelope.
AB - SN 2025coe is a calcium-strong transient located at an extremely large projected offset ∼39.3 kpc from the center of its host, the nearby early-type galaxy NGC 3277 at a distance of ∼25.5 Mpc. In this paper, we present multiband photometric and spectroscopic observations spanning ∼100 days postdiscovery. Its multiband light curves display multiple distinct peaks: (1) an initial peak at t ≍ 1.6 day attributed to shock cooling emission, (2) a secondary peak of MR, peak ≍ −15.8 mag at t ≍ 10.2 days powered by radioactive decay, and (3) a possible late-time bump at t ≍ 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 Mej=0.29−0.15+0.14M⊙, a 56Ni mass of M56Ni=2.4−0.05+0.06×10−2M⊙, and a progenitor envelope with mass Me=1.4−1.2+6.9×10−3M⊙ and radius Re=13.5−11.1+64.1R⊙. 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 56Ni, and the presence of an extended, low-mass envelope.
KW - Supernovae
KW - 1668
KW - High Energy Astrophysical Phenomena
KW - Astrophysics of Galaxies
KW - High Energy Physics - Phenomenology
U2 - 10.3847/1538-4357/ae285c
DO - 10.3847/1538-4357/ae285c
M3 - Article
SN - 0004-637X
VL - 997
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 72
ER -