We present the discovery and follow-up observations of SN 2008jb , a core-collapse supernova in the southern dwarf irregular galaxy ESO 302 - 14 ( M _ { B } = -15.3 mag ) at 9.6 Mpc .
This nearby transient was missed by galaxy-targeted surveys and was only found in archival optical images obtained by the Catalina Real-time Transient Survey and the All-Sky Automated Survey .
The well sampled archival photometry shows that SN 2008jb was detected shortly after explosion and reached a bright optical maximum , V _ { max } \simeq 13.6 mag ( M _ { V, max } \simeq - 16.5 ) .
The shape of the light curve shows a plateau of \sim 100 days , followed by a drop of \sim 1.4 mag in V -band to a slow decline with the approximate ^ { 56 } Co decay slope .
The late-time light curve is consistent with 0.04 \pm 0.01 M _ { \odot } of ^ { 56 } Ni synthesized in the explosion .
A spectrum of the supernova obtained 2 years after explosion shows a broad , boxy H \alpha emission line , which is unusual for normal type IIP supernovae at late times .
We detect the supernova in archival Spitzer and WISE images obtained 8 - 14 months after explosion , which show clear signs of warm ( 600 - 700 K ) dust emission .
The dwarf irregular host galaxy , ESO 302 - 14 , has a low gas-phase oxygen abundance , 12 + log ( O / H ) = 8.2 ( \sim 1 / 5 Z _ { \odot } ) , similar to those of the SMC and the hosts of long gamma-ray bursts and luminous core-collapse supernovae .
This metallicity is one of the lowest among local ( \lesssim 10 Mpc ) supernova hosts .
We study the host environment using GALEX far-UV , R -band , and H \alpha images and find that the supernova occurred in a large star-formation complex .
The morphology of the H \alpha emission appears as a large shell ( R \simeq 350 pc ) surrounding the FUV and optical emission .
Using the H \alpha -to-FUV ratio , and FUV and R -band luminosities , we estimate an age of \sim 9 Myr and a total mass of \sim 2 \times 10 ^ { 5 } M _ { \odot } for the star-formation complex , assuming a single-age starburst .
These properties are consistent with the expanding H \alpha supershells observed in many well-studied nearby dwarf galaxies , which are tell-tale signs of feedback from the cumulative effect of massive star winds and supernovae .
The age estimated for the star-forming region where SN 2008jb exploded suggests a relatively high-mass progenitor star with initial mass M \sim 20 M _ { \odot } , and warrants further study .
We discuss the implications of these findings in the study of core-collapse supernova progenitors .