Red supergiants have been confirmed as the progenitor stars of the majority of hydrogen-rich type II supernovae [ 1 ] .
However , while such stars are observed with masses > 25 { M } _ { \odot } [ 2 ] , detections of > 18 { M } _ { \odot } progenitors remain elusive [ 1 ] .
Red supergiants are also expected to form at all metallicities , but discoveries of explosions from low-metallicity progenitors are scarce .
Here , we report observations of the type II supernova , SN 2015bs , for which we infer a progenitor metallicity of \leq 0.1 { Z } _ { \odot } from comparison to photospheric-phase spectral models [ 3 ] , and a Zero Age Main-Sequence mass of 17-25 { M } _ { \odot } through comparison to nebular-phase spectral models [ 4 , 5 ] .
SN 2015bs displays a normal ‘ plateau ’ light-curve morphology , and typical spectral properties , implying a red supergiant progenitor .
This is the first example of such a high mass progenitor for a ‘ normal ’ type II supernova , suggesting a link between high mass red supergiant explosions and low-metallicity progenitors .