paper

Optical Observations of Type II Supernovae

arXiv:astro-ph/0002264 · doi:10.1063/1.1291705

Abstract

I present an overview of optical observations (mostly spectra) of Type II supernovae. SNe II are defined by the presence of hydrogen, and exhibit a very wide variety of properties. SNe II-L tend to show evidence of late-time interaction with circumstellar material. SNe IIn are distinguished by relatively narrow emission lines with little or no P-Cygni absorption component and (quite often) slowly declining light curves; they probably have unusually dense circumstellar gas with which the ejecta interact. Some SNe IIn, however, might not be genuine SNe, but rather are super-outbursts of luminous blue variables. The progenitors of SNe IIb contain only a low-mass skin of hydrogen; their spectra gradually evolve to resemble those of SNe Ib. Limited spectropolarimetry thus far indicates large asymmetries in the ejecta of SNe IIn, but much smaller ones in SNe II-P. There is intriguing, but still inconclusive, evidence that some peculiar SNe IIn might be associated with gamma-ray bursts. SNe II-P are useful for cosmological distance determinations with the Expanding Photosphere Method, which is independent of the Cepheid distance scale.

18 pages, 10 embedded figures, latex with aipproc style file included, to appear in "Cosmic Explosions" -- eds. S. Holt and W. W. Zhang (New York: American Institute of Physics), 2000

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