27 research outputs found
Spectral evolution of Nova (V1494) Aql and its high velocity jets
No full textSpectral evolution of the fast nova V1494 Aql was monitored soon
after its discovery in December 1999 to September 2000. The first spectra
showed prominent emission lines of H I and Fe II, while He I was seen in
absorption. The radial velocities of the absorption components of H I,
He I and N II rapidly increased (in the negative sense) during the early
decline stage, while those of Fe II remained nearly constant. When a
new spectrum was taken on February 6, 2000 after the seasonal interruption,
this nova was in the transition stage. The spectra in the transition stage
showed emission lines of H I, He I, He II, N II, N III, Si II, [N II], [O I],
[O III], [Fe II], [Fe VI], [Ca V] etc., hence the emission lines of Fe II had
disappeared. A quasi-periodic oscillation of luminosity with a time scale of
about days and a mean amplitude of about 1.2 mag in V band was
seen from February to the middle of April 2000. The emission lines of He II
and [Ca V] disappeared around a light maximum of the oscillation, while the
emission lines of N II and N III strengthened. At the
same time high velocity (-2900 and +2830 km s-1) broad emission wings of
H I lines appeared, which suggest an ejection of high velocity jets.
The excitation state increased throughout the nebular stage. The last
spectra taken in September 2000 showed highly excited emission lines up to
[Fe VII] and [Fe X] λ6374.5.
The interstellar extinction is estimated as from
the equivalent widths of the interstellar absorption components of Na I D1
and D2. Using this result, the distance to the nova is estimated as
kpc. The mass and the helium abundance of the ejecta are
estimated as 6.2 ±
1.4 10 and N(He)/N(H) ±
0.01, respectively. The electron density of the ejecta decreased as
during the nebular stage, where t is time
from light maximum. This low decline rate suggests that the ejecta had a
ring like shape as well a large mass loss which may have continued
throughout the nebular stage
A photometric study of SDSS J081256.85+191157.8: Detection of orbital and negative superhump periods
No full textThe results obtained from unfiltered photometric CCD observations of SDSS J081256.85+191157.8 made during 3 nights in January 2012 are presented. A period of 0.160151(d) +/- 0.000079 was detected in the data. This period is consistent with the previously proposed orbital period of P P-orb = 0.160151(79) day. A quasi-periodicity of 0.148159(86) day was discovered in all data. This period is a negative superhump period. Therefore we suggest that SDSS J081256.85+191157.8 is classified as a negative superhump system. An improved orbital ephemeris is also determined: T-min (HJD) = 2455929.510163(364) + 0.1600 46(46)*E. (C) 2013 Elsevier B.V. All rights reserved
A photometric study of SDSS J081256.85+191157.8: Detection of orbital and negative superhump periods
No full textThe results obtained from unfiltered photometric CCD observations of SDSS J081256.85+191157.8 made during 3 nights in January 2012 are presented. A period of 0.160151(d) +/- 0.000079 was detected in the data. This period is consistent with the previously proposed orbital period of P P-orb = 0.160151(79) day. A quasi-periodicity of 0.148159(86) day was discovered in all data. This period is a negative superhump period. Therefore we suggest that SDSS J081256.85+191157.8 is classified as a negative superhump system. An improved orbital ephemeris is also determined: T-min (HJD) = 2455929.510163(364) + 0.1600 46(46)*E. (C) 2013 Elsevier B.V. All rights reserved
Discovery of irradiation-induced variations in the light curve of the classical nova V2275 Cyg (N Cyg 2001 No. 2)
No full textWe present charge-coupled device (CCD) photometry, light curve and time-series analysis of the classical nova V2275 Cyg (N Cyg 2001 No. 2). The source was observed for 14 nights in total in 2002 and 2003 using an R filter with the 1.5-m Russian-Turkish joint telescope (RTT150) at the TUBITAK National Observatory in Antalya, Turkey, as part of a large programme on the CCD photometry of cataclysmic variables. We report the detection of two distinct periodicities in the light curve of the nova: (a) P-1 = 0.314 49( 15) d [7.6 h], and (b) P-2 = 0.017 079(17) d [24.6 min]. The first period is evident in both 2002 and 2003 whereas the second period is only detected in the 2003 data set. We interpret the first period as the orbital period of the system and attribute the orbital variations to aspect changes of the secondary irradiated by the hot white dwarf (WD). We suggest that the nova was a supersoft X-ray source in 2002 and, perhaps, in 2003. The second period could be a quasi-periodic oscillation originating from the oscillation of the ionization front (due to a hot WD) below the inner Lagrange point or a beat frequency in the system as a result of the magnetic nature of the WD if steady accretion has already been re-established
Study of nova shells .2. FH Serentis 1970 and QU Vulpeculae 1984, nebular expansion, parallax and luminosity
No full textWe present H alpha direct imaging and shell spectroscopic observations of two classical novae: FH Ser 1970 and QU Vul 1984. The distances, reddenings, luminosities at maximum, and the mass of the shell ejected by FH Ser are derived and discussed
Spectral Evolution and Photo-ionization Analysis of Nova Cas 2020 (V1391 Cas)
No full textWe present spectroscopic observations of Nova Cas 2020(V1391 Cas) obtained using the Russian Turkish Telescope during different stages of its 2020 outburst. We followed the spectral evolution of the nova until it entered the nebular phase. The expansion velocity of the ejecta reached 780 . The fluxes of the neutral [O I] lines at wavelengths 6300, 6364, and 5577 were used to calculate the electron temperature and the mass of neutral oxygen in the ejecta. We found average values , which are consistent with the values calculated for other novae. We modeled the nova\u27s ejected envelope 515 days after its discovery and found that the log elemental abundances by number relative to Hydrogen of the envelope are He = -0.7, C = -5.5, O = -2.5, N = -2.0 and Ne = -4.0
CCD photometry of V2275 Cygni (N Cyg 2001 No.2) in 2002-2003
No full textWe present the CCD photometry, light curve and time series analysis of the classical nova V2275 Cyg. The source is observed for 14 nights in total using standard R filters in 2002 and 2003 with the 1.5m Russian-Turkish joint telescope (RTT150) at the TUBITAK National Observatory (TUG) in Antalya Turkey. We report the detection of two periodicities in the light curve of the nova : a) P-1=0.31449(15) d, b) P-2=0.017079(17) d. We propose that the first period is the orbital period of the system as a result of the aspect changes of the secondary irradiated by the hot WD. The second period could be a QPO originating from the oscillation of the ionization front below the inner Lagrange point as predicted by King (1989) or could be a QPO/beat period related to the magnetic nature of the WD
Searching for superhump period of cataclysmic variable AY Psc
No full textThe results obtained from unfiltered photometric CCD observations of AY Psc made during 17, 20 and 12 nights, respectively, in 2003, 2004 and 2005 are presented. A period of 0.21732 +/- 0.00001 d was detected in the data. This period is consistent with the previously proposed orbital period of P(orb) = 0.2173209 d ((Diaz and Steiner, 1990)). Since this period was present in the light curves taken in all three years, with no apparent change in its value or amplitude. it is interpreted as the orbital period of this binary system. In addition, quasi-periodicities of 0.2057 +/- 0.0001 d, 0.2063 +/- 0.0001 d, 0.2072 +/- 0.0001 d for the years 2003, 2004 and 2005, respectively, were also discovered. These periods were interpreted as negative superhump periods and it was seen that they changes from year to year. Therefore AY Psc is then classified as a negative superhump system. (C) 2008 Elsevier B.V. All rights reserved
CCD photometry of V2275 Cygni (N Cyg 2001 No.2) in 2002-2003
No full textWe present the CCD photometry, light curve and time series analysis of the classical nova V2275 Cyg. The source is observed for 14 nights in total using standard R filters in 2002 and 2003 with the 1.5m Russian-Turkish joint telescope (RTT150) at the TUBITAK National Observatory (TUG) in Antalya Turkey. We report the detection of two periodicities in the light curve of the nova : a) P-1=0.31449(15) d, b) P-2=0.017079(17) d. We propose that the first period is the orbital period of the system as a result of the aspect changes of the secondary irradiated by the hot WD. The second period could be a QPO originating from the oscillation of the ionization front below the inner Lagrange point as predicted by King (1989) or could be a QPO/beat period related to the magnetic nature of the WD
A study of RW Ursae Minoris shell
No full textWe find an expansion parallax for the slow nova RW UMi (Nova Ursae Minoris 1956). A narrow-band H-alpha image shows that the diameter of the nova shell in 1995 was 2.94(+0.37)(-0.49) arcsec. We derive a distance of 5250(+590)(-1050) pc, and an absolute magnitude at maximum of M-v = -7.7(+0.3)(-0.4) which are consistent with previous estimates for the nova. We also revised known relations between various parameters of nova systems
