超新星SN 2024gyの観測でIa型超新星の遅延爆発モデルを支持（SN 2024gy Observations Support Ia Supernova Delayed-Detonation Model）

2026-01-13 中国科学院（CAS）

＜関連情報＞

• https://english.cas.cn/newsroom/research_news/phys/202601/t20260114_1145693.shtml
• https://iopscience.iop.org/article/10.3847/1538-4357/ae1ba0

SN 2024gy: Ia型超新星の遅延爆発を示唆する多段階スペクトル特徴 SN 2024gy: Multiepoch Spectroscopic Features Suggestive of Delayed Detonation in a Type Ia Supernova

Liping Li, Zhenyu Wang, Jialian Liu, Yu Pan, Alexei V. Filippenko, Jujia Zhang, Xiaofeng Wang, Brajesh Kumar, Yi Yang, Thomas G. Brink,…
The Astrophysical Journal  Published: 2025 December 22
DOI:10.3847/1538-4357/ae1ba0

Abstract

We present photometric and spectroscopic observations of SN 2024gy, a Type Ia supernova (SN Ia) exhibiting high-velocity features (HVFs) in its early-time spectra. This SN reaches a peak B-band magnitude of −19.25 ± 0.29 mag and subsequently declines by Δm₁₅(B) ≈ 1.12 mag, consistent with the luminosity–width relation characteristic of normal SNe Ia. Based on the peak thermal luminosity of (1.2 ± 0.3) × 10⁴³ erg s⁻¹, we estimate that 0.57 ± 0.14 M_⊙ of ⁵⁶Ni was synthesized during the explosion. Our dense early spectral monitoring revealed significant velocity disparities within the ejecta. Notably, absorption features from the Ca ii near-infrared triplet were observed at velocities exceeding 25,000 km s⁻¹, while the Si ii λ6355 line velocity at the same epoch was significantly lower at ∼16,000 km s⁻¹. This velocity disparity likely reflects distinct ionization states of intermediate-mass elements in the outermost layers. The prominent Ca ii HVFs may originate from ionization suppression within the highest-velocity ejecta, potentially indicative of minimal hydrogen mixing in a delayed-detonation explosion scenario. Additionally, the Ni/Fe ratio derived from the nebular spectrum of SN 2024gy provides further support for this model.