The unique type Ia supernova 2000cx in NGC 524

Citation
Wd. Li et al., The unique type Ia supernova 2000cx in NGC 524, PUB AST S P, 113(788), 2001, pp. 1178-1204
Citations number
85
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC
ISSN journal
0004-6280 → ACNP
Volume
113
Issue
788
Year of publication
2001
Pages
1178 - 1204
Database
ISI
SICI code
0004-6280(200110)113:788<1178:TUTIS2>2.0.ZU;2-Y
Abstract
We present extensive photometric and spectroscopic observations of the Type Ia supernova (SN Ia) 2000cx in the S0 galaxy NGC 524, which reveal it to b e peculiar. Photometrically, SN 2000cx is different from all known SNe Ia, and its light curves cannot be fitted well by the fitting techniques curren tly available. There is an apparent asymmetry in the B-band peak, in which the premaximum brightening is relatively fast (similar to that of the norma l SN 1994D), but the postmaximum decline is relatively slow (similar to tha t of the overluminous SN 1991T). The color evolution of SN 2000cx is also p eculiar: the (B-V)(o) color has a unique plateau phase and the (V-R)(o) and (V-I)(o) colors are very blue. Although the premaximum spectra of SN 2000cx are similar to those of SN 199 1T-like objects (with weak Si ii lines), its overall spectral evolution is quite different. The Si ii lines that emerged near maximum B-band brightnes s stay strong in SN 2000cx until about 3 weeks past maximum. The change in the excitation stages of iron-peak elements is slow. Both the iron-peak and the intermediate-mass elements are found to be moving at very high expansi on velocities in the ejecta of SN 2000cx. We discuss theoretical models for SN 2000cx. SN 2000cx may be an overlumino us object like SN 1991T, but with a larger yield of Ni-56 and a higher kine tic energy in the ejecta. We also briefly discuss the implications of our o bservations for the luminosity versus light-curve width relation.