Spectroscopic detection of resolved ejecta of nova V1494 Aql

ATel #5454; E. A. Barsukova, A. F. Valeev (Special Astrophysical Observatory, Russia), V. P. Goranskij, A. V. Zharova (SAI, Moscow University)
on 8 Oct 2013; 18:06 UT
Credential Certification: Barsukova E.A. (bars@sao.ru)

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We performed spectroscopic observations of V1494 Aql with the Russian 6-m BTA telescope and SCORPIO multi-mode focal reducer around 2013 June 9.97 UT on the 4938 day (or 13.5 years) after the light maximum. Total exposure was 1201 s, seing 1.4 arcsec, spectral resolution 14 A, spectral range 3800-7800 A, and slit position angle ~0. We found spatially resolved structure around H alpha emission line extended by 6.5 arcsecs in angular size and for 2600 km/s along radial velocity. No such features were seen in other lines. The structure may be formed by an empty spherical shell expanding with the velocity of 1300 km/s. Alternatively this structure can be an edge-on ring located along the slit and expanding with the same velocity. The expansion velocity ~0.24 arcsec/year corresponds to a distance of 1.2 +/-0.2 kpc.

The strongest emission line in the spectrum is He II 4686 A. Other He II emissions at 4200, 4542, and 5412 A are identified. Balmer emissions are well presented at shortwave range till H zeta. Flux ratio of H beta to HeII 4686 A is equal to 0.38. There are weak emissions of He I at 4026, 5876 and 6678 A. Other lines are Bowen blend C III/N III, and C IV blend at 5805 A.

V1494 Aql is an eclipsing nova. It is the eastern component of a triple star, its angular distance to the nearest companion is 1.4 arcsec. Using direct BTA/SCORPIO images, we have measured the brightness of the companion 17.73 +/-0.03 mag in the V band. In four nights in June 2013, we carried out photometric monitoring of V1494 Aql with the 60-cm reflector of the SAI Crimean Station (Ukraine) and CCD Apogee-47p in the V band. The combined light for two stars was measured. Two eclipses were observed. Using 22 mid-eclipse times collected since July 2002, we obtained the following improved ephemeris: P = 0.13461610(1) day; T_0 = JD hel. 2456486.4404(5). Subtracting the companion light, we found that out-of-eclipse brightness varied between 17.6 and 18.2 mag, and eclipse minimum brightness varied between 19.6 and 20.2 mag. Duration of eclipses was ~40 minutes.

V1494 Aql has passed supersoft X-ray phase from the 218th to the 516th day after its visual maximum (G.J. Schwarz et al., ApJ Suppl. V.197, p.31, 2011). With such a deep eclipse in visible light, lack of even traces of eclipses in soft X-ray Chandra data is very surprising.

Fragment of the spectrum