Relationship of the content of vitamin D and melatonin in blood serum and pineal gland calcifications in patients with malignant bone tumors

The aim of the study was to investigate the relationship between the vitamin D content, melatonin and the characteristics of pineal gland calcifications in patients with malignant tumors of the bones of the lower extremities. Vitamin D deficiency and pineal gland calcifications are observed in almost 100 % of patients with malignant tumors of the lower extremities’ bones. The high heterogeneity of calcifications and its dynamics during the treatment of patients may indicate the processes of their litholysis and dissolution

Symbiotic stars on Asiago archive plates. I

The rich plate archive of the Asiago observatory has been searched for plates containing the symbiotic stars AS 323, Ap 3-1, CM Aql, V1413 Aql (=AS 338), V443 Her, V627 Cas (=AS 501) and V919 Sgr. The program objects have been found on 602 plates, where their brightness has been estimated against the UBVRI photometric sequences calibrated by Henden and Munari (2000, A&AS 143, 343). AS 323 is probably eclipsing, with a preliminary P=197.6 day period. If confirmed, it would be the shortest orbital period known among symbiotic stars. CM Aql does not seem to undergo a series of outbursts, its lightcurve being instead modulated by a large amplitude sinusoidal variation with a P~1058 day period. V627 Cas presents a secular trend in agreement with the possible post-AGB nature of its cool component.Comment: A&A in pres

Helium Nova on a Very Massive White Dwarf -- A Light Curve Model of V445 Puppis (2000) Revised

V445 Pup (2000) is a unique object identified as a helium nova. Color indexes during the outburst are consistent with those of free-free emission. We present a free-free emission dominated light curve model of V445 Pup on the basis of the optically thick wind theory. Our light curve fitting shows that (1) the white dwarf (WD) mass is very massive (M_WD \gtrsim 1.35 M_\sun), and (2) a half of the accreted matter remains on the WD, both of which suggest that the increasing WD mass. Therefore, V445 Pup is a strong candidate of Type Ia supernova progenitor. The estimated distance to V445 Pup is now consistent with the recent observational suggestions, 3.5 < d < 6.5 kpc. A helium star companion is consistent with the brightness of m_v=14.5 mag just before the outburst, if it is a little bit evolved hot (\log T (K) \gtrsim 4.5) star with the mass of M_He \gtrsim 0.8 M_\sun. We then emphasize importance of observations in the near future quiescent phase after the thick circumstellar dust dissipates away, especially its color and magnitude to specify the nature of the companion star. We have also calculated helium ignition masses for helium shell flashes against various helium accretion rates and discussed the recurrence period of helium novae.Comment: 8 pages including 12 figures, to appear in Ap

The 2010 nova outburst of the symbiotic Mira V407 Cyg

The nova outburst experienced in 2010 by the symbiotic binary Mira V407 Cyg has been extensively studied at optical and infrared wavelengths with both photometric and spectroscopic observations. This outburst, reminiscent of similar events displayed by RS Oph, can be described as a very fast He/N nova erupting while being deeply embedded in the dense wind of its cool giant companion. The hard radiation from the initial thermonuclear flash ionizes and excites the wind of the Mira over great distances (recombination is observed on a time scale of 4 days). The nova ejecta is found to progressively decelerate with time as it expands into the Mira wind. This is deduced from line widths which change from a FWHM of 2760 km/s on day +2.3 to 200 km/s on day +196. The wind of the Mira is massive and extended enough for an outer neutral and unperturbed region to survive at all outburst phases.Comment: MNRAS Letter, in pres

The secondary minimum in YY Her: Evidence for a tidally distorted giant

We present and analyze quiescent UBVRI light curves of the classical symbiotic binary YY Her. We show that the secondary minimum, which is clearly visible only in the quiescent VRI light curves, is due to ellipsoidal variability of the red giant component. Our simple light curve analysis, by fitting of the Fourier cosine series, resulted in a self-consistent phenomenological model of YY Her, in which the periodic changes can be described by a combination of the ellipsoidal changes and a sinusoidal changes of the nebular continuum and line emission.Comment: 5 pages, 2 figures, to appear in Astronomy & Astrophysic

Dust rings and filaments around the isolated young star V1331 Cygni

We characterize the small and large scale environment of the young star V1331 Cygni with high resolution HST/WFPC2 and Digitized Sky Survey images. In addition to a previously known outer dust ring (~30'' in diameter), the HST/WFPC2 scattered light image reveals an inner dust ring for the first time. This ring has a maximum radius of 6.5'' and is possibly related to a molecular envelope. Large-scale optical images show that V1331 Cyg is located at the tip of a long dust filament linking it to the dark cloud LDN 981. We discuss the origin of the observed dust morphology and analyze the object's relation to its parent dark cloud LDN 981. Finally, based on recent results from the literature, we investigate the properties of V1331 Cyg and conclude that in its current state the object does not show suffcient evidence to be characterized as an FU Ori object.Comment: 15 pages ApJ preprint style including 3 figures, accepted for publication in ApJ (Feb. 2007

Evolution of the Symbiotic Nova PU Vul -- Outbursting White Dwarf, Nebulae, and Pulsating Red Giant Companion

We present a composite light-curve model of the symbiotic nova PU Vul (Nova Vulpeculae 1979) that shows a long-lasted flat optical peak followed by a slow decline. Our model light-curve consists of three components of emission, i.e., an outbursting white dwarf (WD), its M-giant companion, and nebulae. The WD component dominates in the flat peak while the nebulae dominate after the photospheric temperature of the WD rises to log T (K) >~ 4.5, suggesting its WD origin. We analyze the 1980 and 1994 eclipses to be total eclipses of the WD occulted by the pulsating M-giant companion with two sources of the nebular emission; one is an unocculted nebula of the M-giant's cool-wind origin and the other is a partially occulted nebula associated to the WD. We confirmed our theoretical outburst model of PU Vul by new observational estimates, that spanned 32 yr, of the temperature and radius. Also our eclipse analysis confirmed that the WD photosphere decreased by two orders of magnitude between the 1980 and 1994 eclipses. We obtain the reddening E(B-V) ~ 0.3 and distance to PU Vul d ~ 4.7 kpc. We interpret the recent recovery of brightness in terms of eclipse of the hot nebula surrounding the WD, suggesting that hydrogen burning is still going on. To detect supersoft X-rays, we recommend X-ray observations around June 2014 when absorption by neutral hydrogen is minimum.Comment: 16 pages including 8 figs, to appear in Ap

Lithium in the Symbiotic Mira V407 Cyg

We report an identification of the lithium resonance doublet LiI 6708A in the spectrum of V407 Cyg, a symbiotic Mira with a pulsation period of about 745 days. The resolution of the spectra used was R~18500 and the measured equivalent width of the line is ~0.34A. It is suggested that the lithium enrichment is due to hot bottom burning in the intermediate mass AGB variable, although other possible origins cannot be totally ruled out. In contrast to lithium-rich AGB stars in the Magellanic clouds, ZrO 5551A, 6474A absorption bands were not found in the spectrum of V407Cyg. These are the bands used to classify the S-type stars at low-resolution. Although we identified weak ZrO 5718A, 6412A these are not visible in the low-resolution spectra, and we therefore classify the Mira in V407 Cyg as an M type. This, together with other published work, suggests lithium enrichment can precede the third dredge up of s-process enriched material in galactic AGB stars.Comment: 4 pages, 2 figures, to be published in MNRA

A new approach towards ferromagnetic conducting materials based on TTF-containing polynuclear complexes

International audienceFive complexes containing binuclear cation [Cu2(LH)2]2+ (LH2 = 1 : 2 Schiff base of 1,3-diaminobenzene and butanedione monoxime) were prepared and characterized. Metathesis of one perchlorate anion in [Cu2(LH)2(H2O)2](ClO4)2 (1) by anionic TTF-carboxylate (TTF-CO2−) leads to the complex [Cu2(LH)2(CH3OH)2](TTF-CO2)(ClO4)*H2O (2). Reactions of 1 with substituted pyridines bipy, dpe and TTF-CH = CH-py result in formation of the complexes {[Cu2(LH)2(bipy)](ClO4)2}n*2nH2O (3), [Cu2(LH)2(dpe)2](ClO4)2*2CH3OH (4) and [Cu2(LH)2(TTF-CH = CH-py)(H2O)](ClO4)2*1.5H2O (5), where bipy = 4,4′-bipyridine, dpe = trans-(4-pyridyl)-1,2-ethylene and TTF-CH = CH-py = 1-(2-tetrathiafulvalenyl)-2-(4-pyridyl)ethylene. Whereas complex 2 is built from discrete ionic particles (with rather long Cu-S contacts), compounds 1 and 3 contain 1D polymeric chains, in which structural units are bonded through Cu-O bonds or through bridging bipy molecule, respectively. Dinuclear complexes 4 and 5 are linked though π-stacking of dpe or TTF-CH = CH-py, respectively. All complexes are characterized by dominating ferromagnetic behavior with J values in the range from +9.92(8) cm−1 to +13.4(2) cm−1 for Hamiltonian H = -JS1S2. Magnetic properties of the compounds, containing stacks of aromatic molecules in crystal structures (4 and 5), correspond to ferromagnetic intradimer and antiferromagnetic intermolecular interactions (zJ′ = −0.158(3) and −0.290(2) cm−1, respectively). It was found that TTF-CH = CH-py ligand in [Cu2(LH)2(TTF-CH = CH-py)(H2O)]2+ could be electrochemically oxidized to cation-radical form in the solution