SN 2025dys: A luminous supernova explosion from a partially stripped helium star
Abstract
We present well-sampled multi-band imaging and low- to medium-resolution spectroscopic observations of the early-discovered Type~II supernova (SN)~2025dys. The photometric evolution exhibits a rise time of ∼\,18 days (r band) and a rapid decline transitioning to the radioactive decay tail at ∼\,70 days. SN~2025dys is among the high-luminosity events with a peak pseudo-bolometric luminosity of Lopt=8.57×1042 erg s−1. Early X-ray emission was identified, displaying a luminosity of 7.55×1040 erg s−1. The observational investigation points to a dense, hydrogen-rich circumstellar medium with a mass of MCSM≈0.5--0.7 M⊙, suggesting a partially stripped, hydrogen-poor inner ejecta with a relatively low mass of Mej≈2.5 M⊙. The explosion possessed a kinetic energy of Ek≈0.3−−0.5~foe and yielded a synthesized nickel mass of MNi≈0.042−0.011+0.012 M⊙. These physical parameters indicate an extreme mass-loss episode before the explosion, characterized by a high mass-loss rate of Ṁ ≳ 0.01 M⊙ yr−1. SN~2025dys represents a stripped progenitor, intrinsically resembling a Type~IIb or even a Type~Ib SN, that exploded within a dense, hydrogen-rich circumstellar environment.
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BibTeX
@misc{zhao20262025dys,
title = {{SN 2025dys: A luminous supernova explosion from a partially stripped helium star}},
author = {Jiewei Zhao and Brajesh Kumar and Gitika Rameshan and Devendra K. Sahu and Bin-Bin Zhang and Kamil Nadaf and Guowang Du and Wenyu Li and Zehui Peng and Jinghua Zhang and Shiyan Zhong and Xiangkun Liu and Avinash Singh and Xinlei Chen and Yuan Fang and Yu Pan and Xingzhu Zou and Hrishav Das and Mridweeka Singh and Amrit Dutta and G. C. Anupama and Xueling Du and Yang Yang and Kaushik Chatterjee and Tao Wang and Xufeng Zhu and Yuan-Pei Yang and Xiaowei Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.41729},
eprint = {2610.41729},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.41729},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - SN 2025dys: A luminous supernova explosion from a partially stripped helium star
AU - Jiewei Zhao
AU - Brajesh Kumar
AU - Gitika Rameshan
AU - Devendra K. Sahu
AU - Bin-Bin Zhang
AU - Kamil Nadaf
AU - Guowang Du
AU - Wenyu Li
AU - Zehui Peng
AU - Jinghua Zhang
AU - Shiyan Zhong
AU - Xiangkun Liu
AU - Avinash Singh
AU - Xinlei Chen
AU - Yuan Fang
AU - Yu Pan
AU - Xingzhu Zou
AU - Hrishav Das
AU - Mridweeka Singh
AU - Amrit Dutta
AU - G. C. Anupama
AU - Xueling Du
AU - Yang Yang
AU - Kaushik Chatterjee
AU - Tao Wang
AU - Xufeng Zhu
AU - Yuan-Pei Yang
AU - Xiaowei Liu
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2610.41729
UR - https://arxiv.org/abs/2610.41729
AB - We present well-sampled multi-band imaging and low- to medium-resolution spectroscopic observations of the early-discovered Type~II supernova (SN)~2025dys. The photometric evolution exhibits a rise time of ∼\,18 days (r band) and a rapid decline transitioning to the radioactive decay tail at ∼\,70 days. SN~2025dys is among the high-luminosity events with a peak pseudo-bolometric luminosity of L_opt=8.57×10^42 erg s^−1. Early X-ray emission was identified, displaying a luminosity of 7.55×10^40 erg s^−1. The observational investigation points to a dense, hydrogen-rich circumstellar medium with a mass of M_CSM≈0.5--0.7 M_⊙, suggesting a partially stripped, hydrogen-poor inner ejecta with a relatively low mass of M_ej≈2.5 M_⊙. The explosion possessed a kinetic energy of E_k≈0.3−−0.5~foe and yielded a synthesized nickel mass of M_Ni≈0.042_−0.011^+0.012 M_⊙. These physical parameters indicate an extreme mass-loss episode before the explosion, characterized by a high mass-loss rate of Ṁ ≳ 0.01 M_⊙ yr^−1. SN~2025dys represents a stripped progenitor, intrinsically resembling a Type~IIb or even a Type~Ib SN, that exploded within a dense, hydrogen-rich circumstellar environment.
ER -