WFST Supernovae in the First Year. II. SN 2024aedt: Systematical Study of a Transitional Type Ia Supernova

Abstract

<p>We present comprehensive photometric and spectroscopic observations of a transitional Type Ia supernova (SN Ia), SN 2024aedt, discovered by the 2.5 m Wide Field Survey Telescope within 1 day of the explosion. Its light curve is characterized by a peak absolute magnitude of <em>M</em>_<em>B</em> = −18.49 ± 0.03 mag and a decline rate of Δ<em>m</em>₁₅(<em>B</em>) = 1.53 ± 0.36 mag, placing the object on the Δ<em>m</em>₁₅(<em>B</em>)–<em>M</em>_<em>B</em> diagram in the transition region between normal and subluminous SNe Ia. Furthermore, the early color evolution and host galaxy environment of SN 2024aedt underscore its transitional nature, sharing properties with both normal and SN 1991bg–like SNe Ia. Light-curve modeling with MOSFiT yields a synthesized ⁵⁶Ni mass of 0.414 ± 0.042 <em>M</em>_⊙and a total ejecta mass of 0.548 ± 0.108 <em>M</em>_⊙. A comparison with theoretical models suggests that the evolutionary trend can be broadly explained by both delayed-detonation and double-detonation (DDet) scenarios, while possible early-excess emissions predicted by DDet cannot be identified given the limited detections soon after the SN explosion. Although the overall spectral evolution of SN 2024aedt is similar to that of other transitional SNe Ia, the spectroscopic comparison reveals diversity in the early-phase blue-end features, which becomes more homogeneous at later phases. This result indicates the importance of early-time observations in understanding the origin of SN Ia diversity.<br></p>