The IR spectral evolution of Nova Sagittarius 2002 #2 and Nova Cassiopeia 2020
ATel #14034; C. E. Woodward (University of Minnesota), D. P.K. Banerjee, (PRL, India), A. Evans (Keele University)
on 21 Sep 2020; 12:45 UT
Credential Certification: C.E. Woodward (chickw024@gmail.com)
Subjects: Infra-Red, Nova
We report recent 0.7 to 2.5 micron spectra obtained on the 3.2m IRTF telescope
using SpeX in cross-dispersed mode with an 0.8 arcsec slit (R = 750) during
broken cloud conditions and moderate seeing (0.9 arcsec at K-band) of
Nova Sgr 2020 #2 (equivalently ASASSN-20ga / AT 2020lrv; ATel #13790, #13801)
on 2020 Sept 19.221 UT and Nova Cas 2020 (TCP J00114297+6611190 = V1391 Cas;
ATel #14006, #14004) 2020 Sept 19.297 UT. The spectra of N Cas 2020 show that
all the lines mentioned in ATel #14006 are present and no significant evolution
is seen in them. However, the first overtone CO emission appears to have either
disappeared or it could be present at a very faint level. A careful analysis is
needed to be certain. Spectra of N Sgr 2002 #2 show marked weakening of the
strength of the hydrogen recombination lines versus those fluxes reported in
ATel #13801, and complete disappearance of deep P-Cygni absorption features.
The detection of the first overtone bands of carbon monoxide bands (ATel #13852)
suggested that dust was likely to form; indeed, this is what is now seen
~80 days later as the spectral energy distribution longward of 2.04 micron shows
a steep rise to the red. Further observations of both novae are encouraged.
These observations were conducted under IRTF program 2020B017. CEW acknowledges
partial support from NASA grant 80NSSC19K0868.