A detailed study spanning approximately a year has been conducted on the Type Ib supernova 2007Y .
Imaging was obtained from X-ray to radio wavelengths , and a comprehensive set of multi-band ( w 2 m 2 w 1 u ^ { \prime } g ^ { \prime } r ^ { \prime } i ^ { \prime } UBVYJHK _ { s } ) light curves and optical spectroscopy is presented .
A virtually complete bolometric light curve is derived , from which we infer a ^ { 56 } Ni-mass of 0.06 M _ { \sun } .
The early spectrum strongly resembles SN 2005bf and exhibits high-velocity features of Ca ii and H \alpha ; during late epochs the spectrum shows evidence of a ejecta-wind interaction .
Nebular emission lines have similar widths and exhibit profiles that indicate a lack of major asymmetry in the ejecta .
Late phase spectra are modeled with a non-LTE code , from which we find ^ { 56 } Ni , O and total-ejecta masses ( excluding He ) to be 0.06 , 0.2 and 0.42 M _ { \sun } , respectively , below 4,500 km s ^ { -1 } .
The ^ { 56 } Ni mass confirms results obtained from the bolometric light curve .
The oxygen abundance suggests the progenitor was most likely a \approx 3.3 M _ { \sun } He core star that evolved from a zero-age-main-sequence mass of 10–13 M _ { \sun } .
The explosion energy is determined to be \approx 10 ^ { 50 } erg , and the mass-loss rate of the progenitor is constrained from X-ray and radio observations to be \lesssim 10 ^ { -6 } M _ { \sun } yr ^ { -1 } .
SN 2007Y is among the least energetic normal Type Ib supernovae ever studied .