Continuing spectroscopic monitoring of Nova Sct 2018
ATel #11859; Paolo Bernardi, David Boyd, Christian Buil, Stephane Charbonnel, Lorenzo Franco, Olivier Garde, Keith Graham, Massimiliano Mannucci, Nico Montigiani, Umberto Sollecchia, Peter Somogyi (ARAS Group
on 16 Jul 2018; 02:05 UT
Distributed as an Instant Email Notice Novae
Credential Certification: S. N. Shore (shore@df.unipi.it)
We report further spectroscopic observations of the classical nova Nova Sct 2018 = TCP J18292290-1430460 between 2018 Jun 30.8 UT and Jul 14.8 UT. Dispersions range from 600 (Alpy600 and low resolution instruments) to 12000 (eShel and LHIRES) between 3700 and 7900A. Signal to noise values range from ~20 to >80. The low resolution spectra displayed little overall change in the spectrum since the observations reported in (ATel #11802). The Balmer lines remain the dominant emission with absorption troughs (and red wings) extending to about -2300 km/s (minimum around -2000 km/s) and narrow absorption at around -900 km/s, the emission profiles were slightly stronger on the blue side. The Halpha to Hbeta emission ratio was about 5 on Jul 14.8. Echelle observations show that the Na I D broad emission appeared between Jul 6.8 and Jul. 7.8 (ATel #11826) and was still present on the Jul 14.8 echelle spectrum, the detached absorption broad absorption features, discernible even at low resolution, are now at -1800 km/s and -1000 km/s but have weakened relative to Jul 7. He I 5876, 6678 show persistent detached absorption at -1800 km/s and no emission. Fe II 4923, 5018 (partly blended in absorption with He I), 5169 all show the same broad absorption components but these appear to be slightly shifted (-1700 km/s,-900 to -1000 km/s) and possibly fragmenting relative to the earlier report. The Fe II emission profiles are show increasingly strong double peaked structure (-460,+670 km/s) with red wings as extended as those of the Balmer and Na I D emission lines. The Si II 6347,6371 lines are now undetectable. No [O I] or forbidden Fe-peak lines have appeared, additional neutral C and O lines are detectable throughout this period (e.g. O I 7773) and the nova remains in the optically thick stage of the expansion, and with the exception of the rapid onset and persistence of the sodium emission, the nova closely resembles the early stages of the Fe-curtain. The details of the individual observations and the reduced spectra are publicly available at http://www.astrosurf.com/aras/Aras_DataBase/Novae/2018_NovaSct2018.htm and ARAS group observations are continuing.
ARAS spectroscopic database