Continuing optical spectroscopic monitoring of PNV J17224490-4137160

ATel #16006; Steve Shore (Univ. Pisa), Stephane Charbonnel, Pascal Le Du, Olivier Garde, Lionel Mulato, Thomas Petit (2SPOT, Chile; ARAS Group), Sean Curry (ARAS Group)
on 23 Apr 2023; 17:39 UT
Distributed as an Instant Email Notice Novae
Credential Certification: S. N. Shore (shore@df.unipi.it)

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Our spectroscopic monitoring of the development of PNV J17224490-4137160 = Nova Sco 2023 (ATel #16002, #16003, #16004) is continuing, using medium resolution spectroscopy of the newly announced classical nova (and possible gamma-ray source) in Scorpius (ATel #16002, #16003, #16004, #16005). New spectra were obtained on 2023 Apr. 23.19 UT (MJD 60057.74) in remote operation (Chile) using an RC12 reflector with sShel echelle fibre spectrograph (R=11000) and an ATIK 460ex camera for a total exposure of 10800 sec (18 exposures, 600 sec each) in the range 3850 - 7600A for a total S/N > 30 (continuum, 4900A). Additional low resolution (R=960) spectra were obtained on Apr 22.6 (MJD 60057.2) with a UVIX600 spectrograph. The lines continue to show multiple absorption components but with systematic changes in their velocities. The optical depth of the ejecta is decreasing, the emission to absorption ratio has steadily increased on all lines. Na I D continues to show the a single pair of well separated but now shifted to -1800 km/s, the emission component extends to +/-2200 km/s. Si II 6346 shows only weak absorption at the same velocity, Si II 4128/30 is absent. The absorption on Fe II 4923, 5018, 5169 is at -1800 km/s (as for Na I) but there is a new higher velocity component at -2200 km/s. Redward emission on Fe II mirrors the absorption features, suggesting a recombining biconical (or at least aspherical ejection). The strength of the second Fe peak spectrum indicates a still high opacity between 2200 - 2700A, which is accessible with Swift grism spectroscopy. Although in a complex part of the spectrum, Ca I 4226 shows a broad (400 km/s) absorption, stronger than the previous observation, at -1600 km/s, lower than Na I D. The feature previously identified as Fe I 5851 is confirmed, the absorption component at -1900 km/s has strengthened since the previous observation. For the Balmer lines, all transitions continue to show strong absorption with widths of order 500 km/s with absorption components detected on all lines through Heps, Halpha: -3300 k/s, -2000, with red wing emission extending to +3500 km/s; Hbeta - Hdelta show the same features with decreasing relative optical depth. In all cases, the absorptions show asymmetric profiles (shaded to the red), the blue edge of the absorption is at -3600 km/s. Ca II H,K: -2000, broad and strong high velocity absorption with only weak emission. There are still no detected neutral helium transitions (e.g., He I 4471, 5896, 6678, 7065). Using the Na I ISM line velocities to delimit the range of the LAB HI 21 cm profile, the derived hydrogen column density is N_H ~ 3.5E21/cm^2; this implies 0.45 < E(B-V) < 0.6, the new observation confirm that the profile is clearly composite (-65, -40 [+/- 5] km/s]), consistent with the 21 cm profile.

ARAS Database: Novae