Spectroscopic Classification of PNV J17581670-2914490 as a classical nova

ATel #14513; Kenta Taguchi, Miho Kawabata, Masayuki Yamanaka, Keisuke Isogai (Kyoto University)
on 6 Apr 2021; 05:25 UT
Credential Certification: Keisuke Isogai (isogai@kusastro.kyoto-u.ac.jp)

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We report our spectrum of the transient PNV J17581670-2914490. We obtained the spectrum on 2021-04-05.828 UT using the fiber-fed integral field spectrograph (KOOLS-IFU; Matsubayashi et al. 2019) mounted on the 3.8-m Seimei telescope (Kurita et al. 2020) at Okayama Observatory of Kyoto University.

As reported to CBAT, this transient was discovered by Andrew Pearce at 8.4 mag (unfiltered) on 2021-04-04.825 UT (see also vsnet-alert for detail). Rob McNaught reported non-detection on 2021-04-02.776 UT (unfiltered limiting mag 11.0). Seiichiro Kiyota reported multicolor photometry results: B = 9.03, V = 8.02, and Ic = 6.82 (these results were reported at 2021-04-05.4188 UT, but the observation time is not reported). Andrew Pearce also reported multicolor photometry results: V = 8.08 on 2021-04-05.482 UT, B = 9.16 on 2021-04-05.483 UT, and I = 6.50 on 2021-04-05.484 UT. ASAS-SN Sky Patrol also reported photometries: in average, it was g = 14.25 on 2021-04-05.290 UT and g = 14.22 on 2021-04-05.458 UT.

Our spectrum shows Balmer lines, Fe II lines, and the Na I D line. Note that the interstellar extinction is not corrected. The Hα line has the P-Cygni profile, whose absorption component is blue-shifted by ∼1000 km/s from the redder emission component (for convenience, we plot the spectrum in two ways: the blue curve is "rest" spectrum in which the emission peak of the Hα line is offset to its rest wavelength to correct the radial velocity of the target. the green one is red-shifted by 1000 km/s from the blue one, for the visibility of absorption components). Fe II lines have absorption profiles whose wavelengths are consistent with the 1000 km/s blue-shift. The Na I D line has a combined profile of a "rest" absorption component and a broad absorption component which is blue-shifted by ∼1000 km/s from the "rest" one. Hidehiko Akazawa also reported his spectrum, confirming our results.

According to our spectrum and the brightness, we conclude that this object is a classical nova. The spectrum is similar to those of the slow nova V1280 Sco in the early stage (Naito et al. 2012, Hanindyo et al. 2008).

Our Spectrum