Near-infrared spectroscopy of Nova Sagittarii 2001 (V4643 Sgr)

Abstract

Near-infrared spectra of the very fast ReiN-type nova, Nova Sagittarii 2001 (V464a Sgr) obtained in the early decline phase and the period 110 to 170 days after the discovery date are presented. The spectrum in the early decline phase is dominated by emission lines of hydrogen and accompanied by fluorescence excited 0 I line at 1.129 I'm. These lines have broad symmetric emission wings with full width at zero intensity (FWZI) corresponding to a velocity of "". 10,000 km S-I. About 120 days after the discovery the K band spectrum is dominated by emission lines due to Si VI and Si VII at 1.963 I'm and 2.476 JIm indicating that the nova had entered .the coronal phase. The line ratios of Brackett series deviate substantially from case B values indicating optical depth effects.