SN 2021aefx

SN 2021aefx is a Type Ia supernova discovered in 2021 in the galaxy NGC 1566.

SN 2021aefx

SN 2021aefx in NGC 1566 at ≈2–21 μm. Left panel: MIRI F1130W PHANGS-JWST image of NGC 1566 showing the location of SN 2021aefx, marked with a green circle. Right panels: zoom-ins on SN 2021aefx in each PHANGS-JWST filter.[1]
Ia
Right ascension	04h 19m 53.402s[2]
Declination	−54° 56′ 53.08″[2]
Distance	17.69 ± 2.02 Mpc[1]
Redshift	0.00502 ± 0.00001[1]
Host	NGC 1566

Discovery

SN 2021aefx was discovered on November 11, 2021, by the Distance Less Than 40 Mpc (DLT40) transient survey in the spiral galaxy NGC 1566 at a distance of 17.69 ± 2.02 Mpc.^[1] It is located 61.2″ west and 36.5″ south of the center.^[2] It was discovered at apparent magnitude of 17.24 and classified as a high-velocity SN Type Ia.^[3]

Observations

Light curves for SN 2021aefx in four photometric bands, plotted from data published by Hosseinzadeh et al. (2022)^[4]

SN 2021aefx was observed in multiband by the Precision Observations for Infant Supernovae Explosions (POISE) a day after discovery. The photometry was obtained on the 1 m Swope Telescope at the Las Campanas Observatory. Observations were acquired twice per night in order to look for small scale fluctuations in the light curve.^[3]

The brightness and close proximity of SN 2021aefx make it an excellent target for nebular-phase James Webb Space Telescope observations. Kwok et al. (2022) and DerKacy et al. (2023) provided the first demonstration of the impressive spectroscopic capabilities of JWST for studying nebular-phase SNe Ia. Their spectra of SN 2021aefx, obtained +255 and +323 days after, respectively, represent the highest-quality look at the emission properties >2.5 μm of SNe Ia to date. Their spectra show prominent emission features from the iron-group elements (Ni, Co, Fe), as well as a wide, flat-topped [Ar iii] profile that indicates a spherical shell of emission.^[1]

Researchers show that "the observations of SN 2021aefx are consistent with an off-center delayed detonation explosion of a near–Chandrasekhar mass (MCh) WD at a viewing angle of −30° relative to the point of the deflagration to detonation transition."^[5]