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Continuing ARAS visible spectroscopic monitoring of the slow classical nova Sct 2017 = ASASSN-17hx

ATel #10737; Joan Guarro, Paolo Berardi, Umberto Sollecchia, Tim Lester, Terry Bohlsen, Paul Luckas, Fran Campos, Lorenzo Franco, Olivier Garde, Christian Buil, Jim Edlin, François Teyssier (ARAS Group)
on 12 Sep 2017; 01:37 UT
Distributed as an Instant Email Notice Novae
Credential Certification: S. N. Shore (shore@df.unipi.it)

Subjects: Optical, Nova

We report the results of our continuing spectroscopic monitoring of the slow classical nova Sct 2017 = ASASSN-17hx (Atel# 10523, #10524, #10527, #10558, #10736) as part of the ongoing program by members of the ARAS group. Spectra span the interval from 2017 Jun 29.6 through Sep. 9 with resolutions ranging from from about 580 to 14000, depending on the spectrograph (Alpy600, LISA, LHIRES, eShel) covering ~3800-7200A and S/N of about 50-100) with exposure times ranging from 3500 to 10400 sec. The sequence spans the light curve interval starting at the plateau following the initial rise through the ongoing second maximum and we report here some preliminary results to indicate the richness of the growing archive and the complexity of the phenomenology. All lines have varied in strength and profile with what appears to be cycling coincident with light curve changes. The Balmer emission line wings varied in extent, first rto 1000 km/s until around Jul. 14, then narrow (500 km/s) through extending to about 500 km/s, showed a dramatic re-broadening to 1000 km/s around Aug. 2 and reaching 1300 km/s by Aug. 20. Although the core of the profile (|vrad|<500 km/s) has become more boxy (like Fe II), he low level extended wings have persisted. Balmer line absorption velocities ranged from -400 km/s (from discovery through Aug. 1), the wings expanded Aug. 13 through Aug. 19 with the narrow absorption at -400 km/s steadily decreasing through Sep. 5. High velocity absorption at -1000 km/s reappeared on Sep. 8 along with increased visibility of the -400 km/s feature, the main changes began around the time of rise to second visible maximum. The Si II 6347,6371 doublet showed strong P Cyg profiles from Jul. 10 through Jul 28, then only absorption through Aug.1, a new absorption features appeared at -800 km/s that persisted (width about 150 km/s) and the emission briefly reappeared through Aug. 7. Fe II 5169 (used as a proxy for the iron absorption spectrum) tracked the Si II lines through Aug. 12, thereafter developing a boxy, complex emission profile with absorption at The Si II doublet disappeared during the local visible minimum and reappeared as strong P Cyg on Aug. 7 with an wings extending to 800 km/s. The low velocity (-300 km/s) absorption reappeared on Sep. 8. The Na I D doublet displayed detached absorption at -300 km/s from around Jul 18 through Aug. 3, when a high velocity absorption appeared at -800 km/s that lasted only a few days, coincident with the appearance of He I 5876 in emission. Na I D absorption has remained otherwise invariant through out this interval. He I 5876 showed a P Cyg profile from Jul 16 through around Jul 18 and disappeared between around Jul 25 - Aug. 1, after which the high velocity absorption at -1000 km/s reappeared through Sep. 8. He I 6678 behaved similarly. No [O I] lines have yet appeared, nor have the C I 6828,7114 lines seen during the Fe-curtain stage of V339 Del and other CO novae. Observations are continuing, all spectra are publicly available though the ARAS database http://www.astrosurf.com/aras/Aras_DataBase/Novae/2017_NovaSct2017.htm

RAS Database for N Sct 2017