The IR coronal line emission phase in onset in V2891 Cygni
ATel #14033; C. E. Woodward (University of Minnesota), D. P.K. Banerjee, (PRL, India), A. Evans (Keele University)
on 21 Sep 2020; 12:24 UT
Credential Certification: C.E. Woodward (chickw024@gmail.com)
Subjects: Infra-Red, Nova
Further to infrared observations of the slow FeII nova V2891 Cygni discussed in
ATel #13759, we report additional 0.7 to 2.5 micron spectra obtained on
2020 Sept 19.258 UT 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). The spectra show that the nova has
evolved into the IR coronal line phase ~ 368 days after outburst exhibiting
[Si VI]1.962 micron, [Ca VIII]2.322 micron, [Si VII 2.428] micron and also
possibly [Al IX] 2.040 micron and [S IX] 1.2520 micron lines, the latter albeit at
low signal-to-noise. Both OI 0.8446 and 1.3164 micron are evident, as are numerous
hydrogen recombination lines with the HeI 2.0581 micron line being of comparable
integrated flux to that of Brackett-gamma at 2.1655 micron. The Brackett-gamma
hydrogen line shows a mild double peaked structure with peaks separated by
~ 750-820 km/s and a FWHM of the order 1400 km/s. P-Cygni absorption features
are absent in the HeI 1.0831 micron line, but the line profile is asymmetric.
No evidence for dust formation is seen. The visible light curve is showing a
plateau in its decline at this epoch typical of novae in the supersoft X-ray
phase (SSS), consistent with the detection of IR coronal line emission (e.g.,
Schwarz et al. 2011, ApJ Suppl. 197, 31). The possibility that the nova is in
the SSS phase needs to be confirmed. Further observations are encouraged.
These observations were conducted under IRTF program 2020B017. CEW
acknowledges partial support from NASA grant 80NSSC19K0868.
