Rapid Infrared spectroscopy of the highly reddened nova AT2021aadi with IRTF + SpeX: Fe II Classification and CO Overtone Emission
ATel #14958; K. De (MIT) reports on behalf of the Palomar Gattini-IR team
on 7 Oct 2021; 14:55 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Kishalay De (kde1@mit.edu)
The transient PGIR21git/Gaia21ejq/AT2021aadi was reported by the
Palomar Gattini-IR survey (ATel #14950) as young and rising highly
reddened Galactic nova. We obtained spectroscopic follow-up of the
nova using SpeX (Rayner et al. 2003) on the NASA Infrared Telescope
Facility. The data were acquired using the SXD and LXD modes with a
0.3 arcsec slit under good seeing conditions (~0.5 arcsec in K band),
for total on source exposure times of 600s in each mode on UT
2021-10-06.
The reduced spectrum covers the wavelength range from 0.75 to 5.3
microns. The spectrum shows a steeply red continuum rising from the
optical to the NIR bands, peaking at ~ 1.6 microns. The continuum is
dominated by a rich emission line complex consisting of H, He, N, O
and Fe lines. We identify numerous features of C I, suggesting a Fe II
classification (Banerjee & Ashok 2012). The strongest lines of H and
He are clearly resolved, showing a complex profile with at least three
peaks and a FWHM of ~ 900 km/s.
We clearly detect strong emission lines in the CO overtone in K band,
suggesting that the nova is likely to form dust. Continued photometric
coverage from Gattini-IR suggests that the nova has just peaked in
J-band and is currently exhibiting a plateau. Optical photometric
observations would be beneficial to detect the start of the dust
formation phase.
We thank the IRTF team, especially Bobby Bus, John Rayner and Miranda
Hawarden-Ogata for assistance with scheduling these observations
(Program 2021B094; PI: De).
