Near-infrared (0.8-2.5 micron) spectroscopy of Nova Sagittarius 1998=v4633 Sagittarii

摘要

The 0.8-2.4 km spectroscopy of the moderately fast Nova Sgr 1998 = V4633 Sgr, obtained approximately 525 and 850 days after peak brightness, revealed an expanding, hydrogen-deficient shell of medium excitation level that increased with time. The strongest lines were He I and He II and the coronal line of Si VI 1.9641 mum. Also prominent were the lines of H I, and coronal Ca VIII 2.3205 mum and Si VII 2.4807 mum. Other lines included the S III lines at 0.9069 and 0.9532 mum and the coronal lines of Al IX 2.0444 mum and Ti VI 1.7155 mum. Five lines that frequently appear in novae spectra remain unidentified: 0.8926, 1.1114, 1.1900, 1.5545, and 2.1000 +/- 0.005 mum. All the observed lines were roughly 1800 km s(-1) wide (FWHM), and no asymmetries or underlying plateaus were seen. The continuum was significantly shallower than a 1/lambda (4) blackbody emission (approximately stellar photosphere) and steepened with age. References: 18