V1716 Sco: Infrared Coronal Line Emission Detected on Day 133
ATel #16222; C. E. Woodward (U. Minnesota, USA), A. Evans (Keele U., UK), D. K.P. Banerjee (PRL, India)
on 1 Sep 2023; 17:17 UT
Credential Certification: C.E. Woodward (chickw024@gmail.com)
Subjects: Infra-Red, Nova
We report 0.7 to 4.2 micron spectra of classical nova V1716 Sco (PNV J17224490-4137160) obtained on 2023 August 31.24 UT on the 3.2m NASA IRTF telescope using SpeX in cross-dispersed mode. The observations were made with a 0.5 arcsecond slit (R=1200) at an airmass between 2.1-2.24 but under photometric conditions and moderate seeing (less than 1.1 arcsec in the K-band). The near infrared spectra, obtained about 133 days after its discovery on 2023 Apr 20.678 UT (CBET#5245), show lines of the hydrogen Pa, Br, Pf and Hu series, the usual lines of He I, HeII and OI, and a rich suite of coronal lines. The strongest line in the spectrum is that of He I 1.0830 micron, the total integrated observed flux of 2.88e-11 ergs/s/cm^2; whereas the Paschen-beta 1.2818 micron line has a total integrated flux of 4.03e-12 ergs/s/cm^2. A large number of coronal lines are seen including [S XII] 0.7613, [S VIII] 0.9914 (total integrated flux of 1.54e-12 ergs/s/cm^2, [S IX] 1.2523 (total integrated flux of 1.49e-12 ergs/s/cm^2), [Si X] 1.4305 (total integrated flux of 1.11e-12 ergs/s/cm^2), [Si IX] 1.5599, [P VIII] 1.7361 possibly, [Si XI] 1.9320, [Si VI] 1.9650, [Al IX] 2.0400 (blended with HeI 2.058), [Ca VIII] 2.3211, [Si VII] 2.4833, [Al V] 2.9052, [Mg VIII] 3.0280, [Ca IV] 3.2067, [Al VI] 3.6597, [Al VIII] 3.6900 and [Si IX] 3.9357 micron. Of these, the [Si X] 1.4305 micron line has the largest ionization potential of 351 eV. The coronal line phase may be expected as the nova is passing through a prominent super-soft X-ray phase at present (ATel#16069). The H lines are boxy, with flat tops with some castellation, for instance the Paschen-beta line profile is well fit by a four component Gaussian. On the other hand, many of the coronal lines show a pronounced double peak structure (velocity separation of order +/- 1000 km/s) with a deep dip between the peaks. The FWHM of Paschen-beta 1.2818 micron line is of the order 2700 km/s.
Further X-ray, optical, and infrared spectroscopic observations are encouraged.
We thank the IRTF staff and telescope operator for assistance with these observations, which were conducted under the NASA IRTF Director's Discretionary Time program 2023B988.
