[논문 리뷰] Spectral Dataset of Stripped-Envelope Supernovae from the Tsinghua Supernova Group

Danfeng Xiang, Xiaofeng Wang외 41명|arXiv (Cornell University)|2026. 03. 13.

Gamma-ray bursts and supernovae인용 수 0

한 줄 요약

이 논문은 2010–2020년 사이에 관측된 249개의 광학 스펙트럼으로 구성된 62개의 SESNe 데이터셋을 제시하고, 측정된 pseudo-equivalent widths와 blueshift velocities를 분석하며, 분광 특징을 분석해 서브타입 경향과 progenitor 질량에 대한 함의를 밝힌다.

ABSTRACT

The extent of envelope stripping in the progenitor stars is directly reflected in the diversity of spectral features observed in stripped-envelope supernovae (SESNe). Through extensive spectral observation and analysis, we aim to clarify the statistical differences between the subclasses of SESNe. The Tsinghua Supernova group obtained 249 optical spectra of 62 SESNe during the years from 2010 to 2020, covering phases from $-$16 to over 190 days relative to maximum light. Most spectra were obtained during the photospheric phases after the supernova explosion. For each spectrum, the pseudo-equivalent widths (pEWs) and blueshift velocities of principal lines were measured. We further investigated the common spectral features by analysing their velocity and strength correlations across all subtypes. We identify the feature near 6200~Å in SNe Ib as H$\mathrmα$ through comparison with SNe IIb and Ic, which resolves inconsistent literature interpretations. Our finding reveals prevalent residual hydrogen in SNe Ib, further supporting a continuous stripping sequence from SNe IIb to Ib. We observe a trend in increasing velocity among different subtypes of stripped-envelope SNe, with SNe IIb exhibiting the lowest line velocities, followed by Ib, Ic, and Ic-BL. Typically, the O~I lines in SNe Ic/Ic-BL are stronger than those seen in SNe IIb/Ib. In nebular phases, the [Ca II] emission dominates over [O I] in SNe IIb/Ib while [O I] is stronger in SNe Ic, including the He-rich SN 2016coi. This spectral dichotomy implies that progenitors of SNe Ic (BL) have more massive CO cores and hence higher initial masses.

연구 동기 및 목표

• Clarify statistical differences among SESNe subclasses by compiling and analyzing a large spectral dataset.
• Quantify spectral feature properties (pEWs and velocities) across phases from pre-maximum to late nebular stages.
• Investigate hydrogen retention and elemental line behavior to infer envelope-stripping sequences and progenitor masses.

제안 방법

• Collect and reduce 249 optical spectra of 62 SESNe observed from 2010–2020.
• Measure pseudo-equivalent widths and blueshift velocities for principal spectral lines.
• Analyze correlations of line velocity and strength across SESNe subtypes.
• Identify spectral features (e.g., feature near 6200 Å) with physical identifications by comparison to SN IIb and Ic.
• Compare nebular-phase line strengths of [Ca II] and [O I] among subtypes to infer core masses.

실험 결과

연구 질문

• RQ1 What are the statistical differences in spectral features among SESNe subtypes (IIb, Ib, Ic, Ic-BL)?
• RQ2 How do line velocities and pEWs correlate across phases and subtypes?
• RQ3 Is the 6200 Å feature in SNe Ib best explained as Hα, and what does this imply about residual hydrogen in SNe Ib?
• RQ4 What do nebular-phase [Ca II] vs [O I] strengths indicate about CO core masses and progenitor initial masses?

주요 결과

• The 6200 Å feature in SNe Ib is identified as Hα by comparison with SNe IIb and Ic, indicating residual hydrogen in SNe Ib.
• There is a general velocity trend with subtype: IIb slowest, followed by Ib, Ic, and Ic-BL with increasing velocities.
• O I lines tend to be stronger in SNe Ic/Ic-BL than in IIb/Ib.
• In nebular phases, [Ca II] dominates over [O I] in IIb/Ib, while [O I] is stronger in Ic and in the He-rich SN 2016coi.
• The results support a continuous envelope-stripping sequence from IIb to Ib and Ic, with more massive CO cores in Ic/ Ic-BL progenitors.