Nova V1708 SCORPII = TCP J17234205-3103072
ATel #14028; Dipankar P. K. Banerjee, Pyysical Research Laboratory, India,
on 18 Sep 2020; 06:03 UT
Credential Certification: Dipankar P.K. Banerjee (dpkb12345@gmail.com)
The source TCP J17234205-3103072 classified in CBET 4848 as V1708 SCORPII = NOVA SCORPII 2020 = TCP J17234205-3103072
has been showing some interesting characteristics. The H-alpha emission line on Sept 14.8 is reported to be broad with a FWZI of about 9,000 km/s on which is superposed a narrower component (Aydi et al. ATel #14015 ). However, if the spectra shown by M. Fujii in VSNET-alert 24684 are examined, the FWZI of the H-alpha line is suggested to be almost 11000-12000 km/s on Sept 10.463. This shows the ejecta may have decelerated in the interim period of 4 days, a behaviour which is likely since the progenitor may be a symbiotic system. Mroz and Udalski (ATel # 14017) say the position of the nova is coincident with a bright variable source with pulsations typical of a semiregular red giant.
Examination of the H-alpha images from the SUPERCOSMOS and VPHAS+ (VST Photometric Halpha Survey of the Southern Galactic Plane and Bulge) databases, show a bright H-alpha source almost coincident with the nova's end figures of 42.05, 07.2, indicating the possibility that this is a symbiotic star. The source is brighter in the H-alpha image than in the R band image in SUPERCOSMOS data. If this is the source that is currently in outburst, then it implies the nova outburst is taking place in a symbiotic system and that further deceleration of the ejecta should be expected as the nova ejecta plows into the ambient wind of the giant.
Since such nova eruptions in a symbiotic system are rare, the object should be pursued further, at high cadence if possible, to document further deceleration of the broad 10,000 km/s component. Accurate astrometry of the nova's position is also most desirable to avoid source-confusion since there are several nearby stars.
