Search results for "STELLA"
showing 10 items of 1995 documents
Oracion evangelica, politico-moral, que predicò a la ... Ciudad de Zaragoza, el dia tercero de Pasqua de Espiritu Santo, en el Templo Metropolitano …
1755
Caplletres grav., fris i altres ornaments tip. Sign.: a-b4, c1, A3, B-E4 Text amb postil·les marginals Reclams
Oracion evangelica, politico-moral, que predicò a la ... Ciudad de Zaragoza, el dia tercero de Pasqua de Espiritu Santo, en el Templo Metropolitano d…
Caplletres grav., fris i altres ornaments tip Sign.: a-b4, c1, A3, B-E4 Text amb postil·les marginals Reclams
La Carta dei Suoli irrigui della dominazione araba (827 – 1072 D.C. ) in agro di Castello Di Baida (Castellammare Del Golfo - TP).
2013
A survey of the weedy communities of Sicily
2007
As Sicily has been a central crossroads of human activity for thousands of years, it offers a major perspective on the Mediterranean weedy plant communities. This syntaxonomical survey of the Sicilian weedy vegetation groups together for the first time 30 plant associations, that have been described from the main and neighboring island in the last three decades. The surveyed vegetation is ascribed to the classes Papaveretea rhoeadis and Stellarietea mediae, whose floristic autonomy is here discussed, and to the orders Aperetalia spicae-venti and Papaveretalia rhoeadis for the former, Polygono-Chenopodietalia polispermi, Solano-Polygonetalia convolvuli, Thero-Brometalia and Urtico-Scrophular…
Food web reconstruction gives evidence of increased trophic levels in no-trawl areas: the red mullet, Mullus barbatus L. case in northern Sicily
2018
This study was aimed at identifying the food web of the red mullet, Mullus barbatus in order to understand how it is affected by trawling disturbance. To achieve this objective: a) the main features of the red mullet habitat were investigated; b) the food web of this habitat was studied in two no-trawl areas and in two areas open to trawling. The working hypothesis is that trawling affects the biochemistry of the sediment and the trophic structure of the benthic assemblage. It was predicted: a) less biomass, smaller size and higher production rate in the benthic assemblages of protected gulfs; b) higher average trophic level for both the red mullet and its predators in protected gulfs; c) a…
Time Resolved X-Ray Spectral Analysis of Class II YSOs in NGC 2264 During Optical Dips and Bursts
2016
Pre-Main Sequence stars are variable sources. The main mechanisms responsible for their variability are variable extinction, unsteady accretion, and rotational modulation of both hot and dark photospheric spots and X-ray active regions. In stars with disks this variability is thus related to the morphology of the inner circumstellar region (<0.1 AU) and that of photosphere and corona, all impossible to be spatially resolved with present day techniques. This has been the main motivations of the Coordinated Synoptic Investigation of NGC2264, a set of simultaneous observations of NGC2264 with 15 different telescopes. We analyze the X-ray spectral properties of stars with disks extracted du…
The magnetosphere of the close accreting PMS binary V4046 Sgr AB
2013
We present a preliminary 3D potential field extrapolation model of the joint magnetosphere of the close accreting PMS binary V4046 Sgr. The model is derived from magnetic maps obtained as part of a coordinated optical and X-ray observing program.
Multi-wavelength observing of a forming solar-like star
2009
V2129 Oph is a 1.35 solar mass classical T Tauri star, known to possess a strong and complex magnetic field. By extrapolating from an observationally derived magnetic surface map, obtained through Zeeman-Doppler imaging, models of V2129 Oph's corona have been constructed, and used to make predictions regarding the global X-ray emission measure, the amount of modulation of X-ray emission, and the density of accretion shocks. In late June 2009 we will under take an ambitious multi-wavelength, multi-observing site, and near contemporaneous campaign, combining spectroscopic optical, nIR, UV, X-ray, spectropolarimetric and photometric monitoring. This will allow the validity of the 3D field topo…
Orbital Evolution of an Accreting Millisecond Pulsar: Witnessing the Banquet of a Hidden Black Widow?
2007
We have performed a timing analysis of all the four X-ray outbursts from the accreting millisecond pulsar SAX J1808.4-3658 observed so far by the PCA on board RXTE. For each of the outbursts we derived the best-fit value of the time of ascending node passage. We find that these times follow a parabolic trend, which gives an orbital period derivative $\dot P_{\rm orb} = (3.40 \pm 0.18) \times 10^{-12}$ s/s, and a refined estimate of the orbital period, $P_{\rm orb} = 7249.156499 \pm 1.8 \times 10^{-5}$ s (reference epoch $T_0 = 50914.8099$ MJD). This derivative is positive, suggesting a degenerate or fully convective companion star, but is more than one order of magnitude higher than what is…
Accretion in young stars: measure of the stream velocity of TW Hya from the X-ray Doppler shift
2015
High-resolution X-ray spectra are a unique tool to investigate the accretion process in young stars. In fact X-rays allow to investigate the accretion-shock region, where the infalling material is heated by strong shocks due to the impact with the denser stellar atmosphere. Here we show for the first time that it is possible to constrain the velocity of the accretion stream by measuring the Doppler shift of the emitted X-rays. To this aim we analyzed the deep Chandra/HETGS observation of the accreting young star TW Hya. We selected a sample of emission lines free from significant blends, fitted them with gaussian profiles, computed the radial velocity corresponding to each line, and average…