Spectroscopic Observations of ASASSN-18fv as a Classical Nova in the Iron Curtain Phase
ATel #11460; Paul Luckas (International Centre for Radio Astronomy Research, University of Western Australia)
on 21 Mar 2018; 17:35 UT
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Observations of ASASSN-18fv (ATel# 11454) were obtained on 2018 Mar. 21.49 (MJD 58199.0), with an Alpy600 spectrograph having a resolution of about 540 in the range 3800-7300A using a Atik414 CCD and a total exposure time 5x120 sec. The spectrum confirms that this source is a classical nova on the rise in the optically thick (Fe curtain) phase, The Fe II 5018, 5169 lines, for instance, show absorption troughs (about as strong as the emission) extending to about -800 km/s, about the same as the zero intensity width of the redshifted emission wing. The Balmer lines (H-alpha to H-gamma) show absorption with similar maximum velocities and strongly decreasing emission-to-absorption ratio with increasing line number, similar profiles and kinematics are found on Si II 6347,6371 and other metallic ion lines. Ca II H and K are mainly in absorption, as are the Na I D lines, but the absorption is displaced by about But in both cases the profiles are broad and poorly resolved, although the Na I D is centered at about vrad=0 km/s while Ca II K has a vrad ~ -400 km/s deepest absorption and a similar maximum absorption velocity, suggesting the Na I line is dominated by interstellar absorption. Neither O I nor He I are seen in this spectrum. The optical depth is quite large now and, with these absorption velocities, it would be of interest to obtain high resolution time sequences to study the appearance of multiple absorption systems and track the changes in ejecta transparency.
ARAS Nova Spectroscopic Database