Type Refinement for SN 2005U in Arp 299
ATel #431; D. C. Leonard and S. B. Cenko (Caltech)
on 28 Feb 2005; 23:01 UT
Credential Certification: Avishay Gal-Yam (email@example.com)
Subjects: Optical, Supernovae
D. C. Leonard and S. B. Cenko report on behalf of the CCCP that a prelinarily reduced spectrum (range 5500 - 9500 A) of the previously identified Type II SN 2005U (Mattila et al., IAUC # 8473 ; Modjaz et al., IAUC # 8475 ) obtained using the double spectrograph mounted on the Palomar Observatory 200" Hale telescope, on Feb. 28, 2005, UT, shows it to resemble the spectrum of the Type IIb SN 1993J over a month past explosion (Matheson et al. 2000, AJ, 120, 1487). In addition to features typically seen in SNe II at this epoch, lines of He I with P-Cyg profiles have emerged, most notably those of 6678 and 7065 in our spectrum. This suggests that the progenitor of SN 2005U lost a substantial fraction of its hydrogen envelope prior to exploding.