Effect of solar activity on the lower atmospheric layers

Solar activity effects on magnetosphere, troposphere, and stratospher

On the origin of a very close similarity between the spectra of the supernova type 1 in NGC 3198 and the absorption of DQ HeR

The type 1 supernova discovered late in 1966 in NGC 3198 has broad minima in its spectrum break down into a number of significantly narrower absorption bands. The broad minima of tau, sigma and mu, which usually show no details in the spectra of type supernovas, contain a number of narrow absorption bands. The reality of most of these absorption bands is demonstrated by comparison of recordings of spectra of the supernova presented for two moments in time. These minima (particularly of tau and mu,) are a result of blending of several broad absorption bands. The minimum of tau should be a blend of intensive and very broad Fe absorption lines, in which the lower level is metastable. The wavelengths of these line are: 5169, 5198, 5235, 5276, 5317, 5363A

Early spectral evolution of Nova Sgr 2004 (V5114 Sgr)

We present optical and near-infrared spectral evolution of the Galactic nova V5114 Sgr (2004) during few months after the outburst. We use multi-band photometry and line intensities derived from spectroscopy to put constrains on the distance and the physical conditions of the ejecta of V5114 Sgr. The nova showed a fast decline (t_2 \simeq 11 days) and spectral features of FeII spectroscopic class. It reached M_V = -8.7 \pm 0.2 mag at maximum light, from which we derive a distance of 7700 \pm 700 kpc and a distance from the galactic plane of about 800 pc. Hydrogen and Oxygen mass of the ejecta are measured from emission lines, leading to 10^{-6} and 10^{-7} M_\odot, respectively. We compute the filling factor of the ejecta to be in the range 0.1 -- 10^{-3} . We found the value of the filling factor to decrease with time. The same is also observed in other novae, then giving support to the idea that nova shells are not homogeneously filled in, rather being the material clumped in relatively higher density blobs less affected by the general expanding motion of the ejecta.Comment: accepted for publication in Astronomy & Astrophysics, 16 pages and 8 figure

The Evolution of Nova V382 Vel 1999

We report results of spectroscopic observations of V382 Vel (Nova Vel 1999) carried out at La Silla between 5 and 498 days after maximum light (23 May 1999, V(max) $\sim 2.3\pm 0.1$). The analysis of the photometric and spectroscopic evolution shows this object to be a {\sl fast nova} belonging to the Fe II {\sl broad} spectroscopic class. A distance of 1.7 kpc ($\pm 20$) is derived from the maximum magnitude vs. rate of decline relationship after correcting for the small reddening toward the nova, E(B--V)\lsim 0.10. From the measured H$\alpha$ flux and the associated rate of expansion we derive an approximate mass for the ejected shell, M_{env}\lsim 10^{-5} M$_\odot$. We have also observed during the early decline a broad, short-lived (\lsim 10 days) feature at 6705-6715 \AA for which several identifications are possible, one of which is the lithium doublet at 6708 \AA and which could place an empirical limit on the lithium production that might occur during the outburst of a {\sl fast nova}. The high luminosity at maximum, M$_v=-8.9$, and the relatively small height above the galactic plane (z\lsim 160pc) suggest that V382 Vel originated from a massive white dwarf, likely in the mass range 1.1--1.2 M$_\odot$.Comment: 13 pages + 9 plots(gif). Accepted by A&