More on Peculiar Abundances in Dwarf Novae and NLs: Implications for Past Novae Explosions

摘要

Enhanced abundances of P, Mn and Al and a general enhancement of N/C ratios provide the first direct evidence that past thermonuclear runaways have occurred on the white dwarfs in dwarf novae and novalikes and indicate that these systems share a common history. Four different types of observations (elevated Al in HST spectra, unusual N/C ratios in FUSE and IUE spectra, the CN blend in optical spectra and low CO in IR spectra) show that a wide variety of systems exhibit peculiar abundances. Since these abundances share a common pattern, they provide clues to the past history of these systems, yet also provoke unsolved questions.