V3890 Sgr- Near-infrared spectrum reveals a return to quiescence
ATel #13764; C. E. Woodward (University of Minnesota), D. P.K. Banerjee (Physical Research Laboratory, India), A. Evans (Keele University)
on 27 May 2020; 17:00 UT
Credential Certification: Dipankar P.K. Banerjee (dpkb12345@gmail.com)
Subjects: Infra-Red, Nova
A near-infrared spectrum (0.7 - 2.5 micron) of the recurrent nova V3890 Sgr
(ATel #13096, #13088, #13047) obtained on 2020 May 20.525 UT at the NASA IRTF
3.2-m telescope using SpeX in cross-dispersed mode (with a 0.8 arcsec wide slit, in subarcsecond
seeing condition) reveals the system has returned to quiescence after its recent
eruption in August 2019.
The spectrum shows no evidence of the coronal emission lines that were seen earlier
from the nova ejecta (ATel #13088). Overall the spectrum is typical of that seen in
symbiotic systems (see Munari and Zwitter 2002, A&A 338, 188) and is dominated by
spectral features of the M-type red giant. Hydrogen lines of Brackett-gamma (2.166
micron), Pa-6, -7 are all weak and narrow (the peak-to-continuum ratio of the Pa beta line, the strongest Hydrogen line in the near-IR spectrum, is only ~1.2). The broad pedestal
upon which the Pa-beta 1.2812 micron line was superposed is not evident, while the HeI
2.0581 micron line was not detected. The first overtone bands of 12C16O arising from
the atmosphere of the cool secondary are in absorption, with bandheads at 2.2295 (v = 2-
0), 2.3227 (v = 3-1), 2.3525 (v = 4-2), 2.3829 (v = 5-3) and 2.4461 (v = 6-4) micron.
The second overtone bands of CO in the H band are also seen. Apart from the Brackett
and Paschen lines, some of the other lines seen in emission are the near-IR Ca II triplet
(0.8498, 0.854, and 0.8662 micron) and OI 0.8446 & OI 1.1287. Notably, the He I
1.0830 micron emission line has a strong P Cygni profile with the emission peak and
absorption minimum separated by ~400 km/s.
These observations were conducted under IRTF program 2020A010, and we thank
Greg Engh (U. Hawaii, IFA) for the assistance. We acknowledge partial support from
NASA grant 80NSSC19K0868.
