Aims. Nova Cyg 2006 has been intensively observed throughout its full outburst. We investigate the energetics and evolution of the central source and of the expanding ejecta, their chemical abundances and ionization structure, and the formation of dust. Methods. We recorded low, medium, and/or high-resolution spectra (calibrated into accurate absolute fluxes) on 39 nights, along with 2353 photometric UBVR c I c measures on 313 nights, and complemented them with IR data from the literature. Results. The nova displayed initially the normal photometric and spectroscopic evolution of a fast nova of the FeII-type. Premaximum, principal, diffuse-enhanced, and Orion absorption systems developed in a normal way. After the initial outburst, the nova progressively slowed its fading pace until the decline reversed and a second maximum was reached (eight months later), accompanied by large spectroscopic changes. Following the rapid decline from second maximum, the nova finally entered the nebular phase and formed optically thin dust. We performed a photo-ionization analysis of the emission-line spectrum during the nebular phase, which showed a strong enrichment of the ejecta in nitrogen and oxygen, and none in neon, in agreement with theoretical predictions for the estimated 1.0 M white dwarf in Nova Cyg 2006. The similarities with the poorly investigated V1493 Nova Aql 1999a are discussed.
We present and discuss accurate and densely mapped BV R C I C lightcurves of the neon Nova Mon 2012, supplemented by the evolution in Stromgren b and y bands and in the integrated flux of relevant emission lines. Our monitoring started with the optical discovery of the nova (50 days past the first detection in gamma-rays by Fermi-LAT) and extend to day +270, well past the end of the super-soft phase in X-rays. The nova was discovered during the nebular decline, well past t 3 and the transition to optically thin ejecta. It displayed very smoothly evolving lightcurves. A bifurcation between y and V light-curves took place at the start of the SSS phase, and a knee developed toward the end of the SSS phase. The apparent magnitude of the nova at the unobserved optical maximum is constrained to +2.8 V 4.2. The appearance, grow in amplitude and then demise of a 0.29585 (±0.00002) days orbital modulation of the optical brightness was followed along the nova evolution. The observed modulation, identical in phase and period with the analog seen in the X-ray and satellite ultraviolet, has a near-sinusoidal shape and a weak secondary minimum at phase 0.5. We favor an interpretation in terms of super-imposed ellipsoidal distortion of the Roche lobe filling companion and irradiation of its side facing the WD. Similar lightcurves are typical of symbiotic stars where a Roche lobe filling giant is irradiated by a very hot WD. Given the high orbital inclination, mutual occultation between the donor star and the accretion disk could contribute to the observed modulation. The optical+infrared spectral energy distribution of Nova Mon 2012 during the quiescence preceeding the outburst is nicely fitted by a early K-type main-sequence star (∼K3V) at 1.5 kpc distance, reddened by E B−V =0.38, with a WD companion and an accretion disk contributing to the observed blue excess and moderate Hα emission. A typical early Ktype main-sequence star with a mass of ∼0.75 M ⊙ and a radius of ∼0.8 R ⊙ , would fill its Roche lobe for a P=0.29585 day orbital period and a more massive WD companion (as implied by the large Ne overabundance of the ejecta).
We provide AAVSO Photometric All-Sky Survey (APASS) photometry in the Landolt BV and Sloan g r i bands for all 425,743 stars included in the fourth RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as the error of the mean of data obtained and separately calibrated over a median of four distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014, and 0.021 mag for the B, V, g , r , and i bands, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been χ 2 fitted to a densely populated synthetic photometric library designed to widely explore temperature, surface gravity, metallicity, and reddening. Resulting T eff and E B−V , computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process, we find that the reddening caused by a homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for E poles B−V = 0.036 ± 0.002 at the Galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b| 25 • .
The B V I lightcurves of seven recent novae have been extensively mapped with daily robotic observations from Atacama (Chile). They are V1534 Sco, V1535 Sco, V2949 Oph, V3661 Oph, MASTER OT J010603. 18-744715.8, TCP J1734475-240942 and ASASSN-16ma. Five belong to the Bulge, one to SMC and another is a Galactic disk object. The two program novae detected in γ-rays by Fermi-LAT (TCP J1734475-240942 and ASASSN-16ma) are Bulge objects with unevolved companions. They distinguish themselves in showing a double-component optical lightcurve. The first component to develop is the fireball from freely-expanding, ballistic-launched ejecta with the time of passage through maximum which is strongly dependent on wavelength (∼1 day delay between B and I bands). The second component, emerging simultaneously with the nova detection in γ-rays and for this reason termed gamma, evolves at a slower pace, its optical brightness being proportional to the γ-ray flux, and its passage through maximum not dependent on wavelength. The fact that γ-rays are detected from novae at the distance of the Bulge and at peak flux levels differing by 4× seems to contradict some common belief like: only normal novae close to the Sun are detected by Fermi-LAT, most normal novae emit γ-rays, and they emit γ-rays in similar amounts. The advantages offered by high-quality photometric observations collected with only one telescope (as opposed to data provided by a number of different instruments) are discussed in connection to the actual local realization of the standard filter bandpasses and the spectrum of novae dominated by emission lines. It is shown how, for the program novae, such high-quality and single-telescope optical photometry is able to disentangle effects like: the wavelength dependence of a fireball expansion, the recombination in the flashed wind of a giant companion, the subtle presence of hiccups and plateaus, tracing the super-soft X-ray phase, and determining the time of its switch-off. The non-detection by 2MASS of the progenitor excludes a giant or a sub-giant being present in four of the program novae (V2949 Oph, V3661 Oph, TCP J18102829-2729590, and ASASSN-16ma). For the remaining three objects, by modelling the optical-IR spectral energy in quiescence it is shown that V1534 Sco contains an M3III giant, V1535 Sco a K-type giant, and MASTER OT J010603.18-744715.8 a sub-giant.
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