Nova ASASSN-17hx fast returning to maximum brightness, now at much larger velocities
ATel #10736; U. Munari (INAF Padova), P. Ochner (Univ. Padova), F.-J. Hambsch, A. Frigo, F. Castellani, A. Milani, P. Valisa, A. Vagnozzi (ANS Collaboration)
on 11 Sep 2017; 21:54 UT
Credential Certification: U. Munari (ulisse.munari@oapd.inaf.it)
Referred to by ATel #: 10737
Nova ASASSN-17hx continues its unexpected and rapid re-brightening (ATel
#10725), approaching the brightness attained at primary maximum when it
peaked at B=9.65, V=8.44, R=7.79, I=7.05 around July 30.1 UT (ATel
#10641). Our daily photometry from Italy and Chile shows that, after
declining to a minimum B=11.81, V=11.01, R=9.54, I=9.40 around Sept 5.0 UT,
well past t(2), the nova abruptly begun a rapid rise in brightness, reaching
B=9.88, V=9.01, I=7.77 on our last measurement for Sept 11.0 UT. The
starting brightness and the rising pace of the current re-brightening
episode resemble closely the final rise toward the first maximum, that
suddenly begun on July 21 after a protracted plateau phase.
As part of our continuing spectroscopic monitoring of ASASSN-17hx we have
just obtained an Echelle spectrum on Sept 11.80 UT with the Varese 61cm and
an Astrolight mk.III multi-mode spectrograph. The spectrum is that typical
of FeII novae around maximum, with strong Balmer and FeII emission lines
from various multiplets, and no significant He lines. The Balmer and FeII
lines present structured and multi-component P-Cyg absorptions. The
absorption for H-alpha is composed by at least three components, at -500,
-875 and -1130 km/s (with FWHM=115, 235 and 210 km/s, respectively). The
Halpha emission, with a photo-center close to null heliocentric radial
velocity, measures FHWM=770 km/s. Both the FWHM of the emission and the
radial velocity of the absorptions are now much larger than observed during
the rise toward the primary maximum of July 30.
