Rare Supernova Defies Expectations With Extended Brightness
Astronomers observed a hydrogen-rich supernova that stayed abnormally bright for weeks longer than typical, releasing energy equivalent to billions of suns. The discovery challenges current models of stellar death and could reshape how scientists predict extreme cosmic explosions—relevant for space agencies and observatories planning next-generation detection systems.
Originaltitel: SN 2021aaev: A Hydrogen-rich Superluminous Supernova with Early Flash and Long-lived Circumstellar Interaction in an Unusual Host Environment
<p>We present photometric and spectroscopic observations of SN 2021aaev, a hydrogen-rich, superluminous supernova with persistent (at least ∼100 days) narrow Balmer lines (SLSN-IIn) at redshift <em>z</em> = 0.1557. SN 2021aaev rose over 28.1 ± 1.0 rest-frame days after explosion, reaching a peak absolute magnitude of −21.46 ± 0.01 in the ATLAS <em>o</em> band. The prepeak spectra resemble those of typical Type IIn SNe with flash-ionization features arising from the interaction with a dense, confined circumstellar medium (CSM), albeit the flash timescale is longer than usual (>20 days). Postpeak, the narrow emission lines evolve slowly, and the absence of ejecta features indicates strong deceleration by the CSM. The total radiated energy (about 1.41 × 10<sup>51</sup> erg) is possibly explained by a low-mass (1–2 <em>M</em><sub>⊙</sub>) ejecta ploughing into a massive (9–19 <em>M</em><sub>⊙</sub>), extended (outer radius >1 × 10<sup>16</sup> cm) H-rich CSM, or alternatively by magnetar-powered models. Interestingly, the host environment consists of a spiral galaxy with a red substructure in the southeastern part, and the SN’s exact location coincides with this quiescent red region (star formation rate <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?=%5C,0.0%7B2%7D_%7B-0.02%7D%5E%7B+0.13%7D%5C,%7BM%7D_%7B%5Codot%20%7D" data-classname="equation" data-title="" /> yr<sup>−1</sup>). Given the atypical environment and the obscuring effect of the massive CSM, a thermonuclear (Type Ia-CSM) origin cannot be ruled out. Altogether, SN 2021aaev is a compelling case to study the diversity of SLSN-IIn features and their host environments.</p>