SN 1990U was a type Ic supernova event in the nucleus of the galaxy NGC 7479. It was discovered July 27, 1990 by the Berkeley Automated Supernova Search after reaching magnitude 16±0.5.[1] Initially this was classified as a Type Ib supernova, but the weakness of the neutral helium absorption lines led to a reclassification.[4]
References
^ abcdGomez, G.; Lopez, R. (July 1994), "Spectral evolution of the He-Poor supernovae 1990U in NGC 7479 and 1991A in IC 2973", The Astronomical Journal, 108 (1): 195–201, Bibcode:1994AJ....108..195G, doi:10.1086/117058
^Modjaz, M.; Kewley, L.; Bloom, J. S.; Filippenko, A. V.; Perley, D.; Silverman, J. M. (April 2011), "Progenitor Diagnostics for Stripped Core-collapse Supernovae: Measured Metallicities at Explosion Sites", The Astrophysical Journal Letters, 731 (1): 6, arXiv:1007.0661, Bibcode:2011ApJ...731L...4M, doi:10.1088/2041-8205/731/1/L4, S2CID56147580, L4