Supernova LSQ13abf was discovered soon after explosion by the La Silla-QUEST Survey and followed by the Carnegie Supernova Project II at optical and near-IR ( NIR ) wavelengths .
Our analysis indicates LSQ13abf was discovered within two days of explosion and its first \approx 10 days of evolution reveal a B -band light curve with an abrupt drop in luminosity .
Contemporaneously , the V -band light curve exhibits a rise towards a first peak and the r - and i -band light curves show no early peak .
The early light-curve evolution of LSQ13abf is reminiscent of the post explosion cooling phase observed in the Type Ib SN 2008D , and the similarity between the two objects extends over weeks .
Spectroscopically , LSQ13abf also resembles SN 2008D with P Cygni He i features that strengthen over time .
Spectral energy distributions are constructed from broad-band photometry , and by fitting black-body ( BB ) functions a UVOIR light curve is constructed , and the underlying BB-temperature and BB-radius profiles are estimated .
Explosion parameters are estimated by simultaneously fitting an Arnett model to the UVOIR light curve and the velocity evolution derived from spectral features , and a post-shock breakout cooling model to the first two epochs of the bolometric evolution .
This combined model suggests an explosion energy of 1.27 \pm 0.23 \times 10 ^ { 51 } ergs , a relatively high ejecta mass of 5.94 \pm 1.10 M _ { \odot } , a ^ { 56 } Ni mass of 0.16 \pm 0.02 M _ { \odot } , and a progenitor-star radius of 28.0 \pm 7.5 R _ { \odot } .
The ejecta mass suggests the origins of LSQ13abf lie with a > 25 \leavevmode \nobreak M _ { \odot } zero-age-main-sequence mass progenitor and its estimated radius is three and nine times larger than values estimated from the same analysis applied to observations of SN 2008D and SN 1999ex , respectively .
Alternatively , comparison of hydrodynamical simulations of \gtrsim 20-25 M _ { \odot } zero-age-main-sequence progenitors that evolve to pre-supernova envelope masses of \lesssim 10 M _ { \odot } and extended ( \sim 100 R _ { \odot } ) envelopes also broadly match the observations of LSQ13abf .