Late-Time Spectroscopy of Supernova 2023ufx Constrains Progenitor Mass and Pre-Explosion Mass Loss in Low-Metallicity Host
What Was Observed (Empirical Data)
Deep nebular spectroscopy of Type II supernova 2023ufx obtained approximately one year post-explosion revealed a triple-peaked [O I] emission profile and a low [Ca II]/[O I] line ratio of ~0.4. Late-time photometry at roughly two years demonstrated light-curve flattening accompanied by diminishing, broad, boxy Hα emission. Optical and near-infrared imaging characterized the host as a dwarf galaxy with a stellar mass of 10^(6.6±0.1) M_☉ and star formation rate of 10^(-2.5±0.1) M_☉/yr, yielding an inferred environmental metallicity of 0.02–0.07 Z_☉.
The Reality Check (Anti-Hype Analysis)
The inferred zero-age main sequence mass of 25–35 M_☉ and asymmetric ejecta structure are derived from synthetic spectral modeling rather than direct pre-explosion progenitor detection. Evidence of late-time interaction points to episodic mass-loss history in a stripped red supergiant, fitting established core-collapse frameworks rather than indicating exotic explosion physics. Furthermore, the low metallicity is constrained primarily through host galaxy integrated SED fitting and scaling relations rather than localized in-situ abundance measurements.
PRIMARY SOURCE:
arXiv Astrophysics (astro-ph)