Nova Cygni 1992: Results of the McDonald Observatory monitoring program
Session 53 -- Recent Observational Results on Nova Cygni 1992
Oral presentation, Wednesday, 1, 1994, 2:00-5:30

## [53.06] Nova Cygni 1992: Results of the McDonald Observatory monitoring program

Robert A. Benjamin (U. of Texas)

We have monitored Nova Cygni 1992 in the near-infrared ($1 - 2.5 \mu m$) from June 1992 to July 1993 from McDonald Observatory. Our observations were made using a InSb array grating spectrometer at resolving powers of 100-600, and concentrated primarily in the K band. The degree of ionization of the ejecta continued to increase during the monitoring period , with ions spanning a range of ionization potentials from He II (I.P.=24 eV) to S IX (I.P.=328 eV) successively appearing and strengthening relative to the continuum emission. We argue that the line and continuum emission arises primarily in photoionized gas rather than shock heated gas, and interpret the spectral evolution as being due to the declining density of the ejecta and rising surface temperature of the white dwarf which photoionizes the nova shell. We use our data to constrain the ejecta density and white dwarf surface temperature and compare our results to those based on monitoring campaigns in other spectral regions.