The Circumstellar Material around the Type IIP SN 2021yja

Abstract The majority of Type II-plateau supernovae (SNe IIP) have light curves that are not compatible with the explosions stars in a vacuum; instead, require progenitors to be embedded circumstellar matter (CSM). We report on successful fitting well-observed SN IIP 2021yja as core-collapse explosion massive star an initial mass ∼15 M ⊙ and pre-explosion radius 631 R . To explain early-time behavior broadband curves, presence 0.55 CSM within ∼2 × 10 14 cm is needed. Like many other SNe IIP, exhibits flux excess including ultraviolet wavelengths. This, together short rise time (<2 days) gri bands, indicates compact component CSM, essentially adjacent progenitor. discuss origin preexisting which most likely common property highly convective red supergiant envelopes. argue difficulty entire curve one spherical distribution around progenitor was asymmetric.