Optical photometry and spectroscopy of Nova Cyg 2014
ATel #6060; T. Tomov, E. Swierczynski, D. Puchalski (Uniwersytet Mikolaja Kopernika, Torun, Poland), D. Dimitrov, D. Chanliev, A. Kurtenkov, T. Bonev (Institute of Astronomy and NAO, Sofia, Bulgaria), D. Marchev, D. Kjurkchieva (Shumen University, Shumen, Bulgaria)
on 10 Apr 2014; 10:12 UT
Credential Certification: Toma Tomov (tomtom@astri.uni.torun.pl)
We report first results from the observations of Nova Cyg 2014 (PNV J20214234+3103296) between
April 2.125 UT and April 9.104 UT. Two identical 60 cm Cassegrain telescopes were used for the
photometric observations. The telescope at the Nicolaus Copernicus University Observatory
(Torun, Poland) was equipped with a SBIG STL-1001 camera. The data from April 2.125 UT allowed
us to estimate the brightness of the Nova as B=11.91+/-0.02 mag, V=10.98+/-0.02 mag and
R=10.37+/-0.02 mag. The 60 cm Rozhen telescope (Rozhen Observatory, Bulgaria) was equipped by
a FLI PL09000 camera. According to The Rozhen data the Nova magnitudes on April 9.104 UT were
B=10.56+/-0.03 mag, V=9.66+/-0.02 mag and R=8.99+/-0.03 mag. We established a monotonic increase
of the brightness by ~0.03 mag in all bands during the 40-minute run on April 9.
The moderate-resolution spectral observations (R~2300) were performed in the 5100-6850 AA range
using the grizm spectrograph attached to the 2 m RCC telescope at Rozhen Observatory on
April 2.129 UT and April 4.079 UT. Moreover, high-resolution spectra (R~16000) in regions
covering ~200 A around the lines Halpha, Hbeta and NaI were obtained using the Coude spectrograph
of the Rozhen 2 m RCC telescope. Our spectral observations confirmed that the object is a
"Fe II"-type classical Nova (see Arai & Ayani, CBET 3482) because the spectrum is dominated by
lines of the Fe II multiplets 42, 49, 74, etc. The lines Halpha and Hbeta were also strong.
All spectral lines showed P Cyg type profiles.
We measured the radial velocities of the emission and absorption components of the lines,
deblending them by fitting Gaussians. The average radial velocities of the emission features
were respectively -150+/-20 km/s on April 2, -125+/-19 km/s on April 4 and -125+/-9 km/s on April 9.
The corresponding average velocities of the absorption features were -425+/-40 km/s,
-370+/-44 km/s and -400+/-35 km/s. The FWHM of the Halpha emission and absorption components were
~450 km/s on April 2. The FWHM of the Halpha emission features corresponded to ~380 km/s both
on April 4 and 9 while their absorption components revealed different FWHM: ~330 km/s on April 4
and ~250 km/s on April 9. The FWHM of the Hbeta emission and absorption components were respectively
300 km/s and 250 km/s on April 4 and April 9.
The strong interstellar absorption lines of Na I and several DIBs (5780 A, 6282 A, 6614 A) in our
spectra are consistent with the significant reddening of the Nova, noted by Munari et al. (CBET 3482). The Na I interstellar features were single absorptions with radial velocity of -3.4+/-0.6 km/s and EW of 1.05+/-0.04 A for the 5889 A line and 0.82+/-0.03 A for the 5895 A line. Using the calibrations of Poznanski et al. (2012) for the EW of the particular Na I lines and their sum, we obtained E(B-V)=2.10+/-0.23 mag. This value is considerably larger than the maximum interstellar reddening of ~0.88 mag to the Nova direction (Schlegel et al. 1998; Schlafly & Finkbeiner 2011) taken from NASA IPAC Infrared Science Archive (IRSA).
Our data, the AAVSO observations and the data published in CBET 3482 show that Nova Cyg 2014 is most probably a relatively slow nova, discovered during its pre-max halt in the first week of April. The photometric observations obtained during the last several days (see also the AAVSO light curve and vsnet-alert 17182) indicate that the nova is on its final brightness rise since April 8.
