A white dwarf-neutron star relativistic binary model for soft gamma-ray repeaters

A scenario for SGRs is introduced in which gravitational radiation reaction effects drive the dynamics of an ultrashort orbital period X-ray binary embracing a high-mass donor white dwarf (WD) to a rapidly rotating low magnetised massive neutron star (NS) surrounded by a thick, dense and massive accretion torus. Driven by GR reaction, sparsely, the binary separation reduces, the WD overflows its Roche lobe and the mass transfer drives unstable the accretion disk around the NS. As the binary circular orbital period is a multiple integer number ($m$) of the period of the WD fundamental mode (Pons et al. 2002), the WD is since long pulsating at its fundamental mode; and most of its harmonics, due to the tidal interaction with its NS orbital companion. Hence, when the powerful irradiation glows onto the WD; from the fireball ejected as part of the disk matter slumps onto the NS, it is partially absorbed. This huge energy excites other WD radial ($p$-mode) pulsations (Podsiadlowski 1991,1995). After each mass-transfer episode the binary separation (and orbital period) is augmented significantly (Deloye & Bildsten 2003; Al\'ecyan & Morsink 2004) due to the binary's angular momentum redistribution. Thus a new adiabatic inspiral phase driven by GR reaction starts which brings the binary close again, and the process repeats. This model allows to explain most of SGRs observational features: their recurrent activity, energetics of giant superoutbursts and quiescent stages, and particularly the intriguing subpulses discovered by BeppoSAX (Feroci et al. 1999), which are suggested here to be {\it overtones} of the WD radial fundamental mode (see the accompanying paper: Mosquera Cuesta 2004b).Comment: This paper was submitted as a "Letter to the Editor" of MNRAS in July 17/2004. Since that time no answer or referee report was provided to the Author [MNRAS publication policy limits reviewal process no longer than one month (+/- half more) for the reviewal of this kind of submission). I hope this contribution is not receiving a similar "peer-reviewing" as given to the A. Dar and A. De Rujula's "Cannonball model for gamma-ray bursts", or to the R.K. Williams' "Penrose process for energy extraction from rotating black holes". The author welcomes criticisms and suggestions on this pape

A determination of the LMC dark matter subhalo mass using the MW halo stars in its gravitational wake

Our goal is to study the gravitational effects caused by the passage of the Large Magellanic Cloud (LMC) in its orbit on the stellar halo of the Milky Way (MW). We employed the Gaia Data Release 3 to construct a halo tracers data set consisting of K-Giant stars and RR-Lyrae variables. Additionally, we have compared the data with a theoretical model to estimate the DM subhalo mass. We have improved the characterisation of the local wake and the collective response due to the LMC orbit. On the other hand, we have estimated for the first time the dark subhalo mass of the Large Magellanic Cloud, of the order of $2\times 10^{11}$ M$_{\odot}$, comparable to previously reported values in the literature.Comment: submitted to A&

Effect of Tree Species and Density on Pasture Production in Galicia, Spain

Galicia produces 50% of the forest products of Spain. Livestock production earns 62% of the income of the agrarian sector in Galicia. Afforestation has been very important in the last decade to such an extent that the area of forest and woodlands now covers 62% of Galicia. It is necessary to increase the rate of return on investments in planted forests in order to avoid rural depopulation through improvement of rural development and welfare. This paper reports on the effect of combining pastures with trees

Seasonal Variation of Crude Protein Content of Different Herbaceous, Shrub and Tree Species

Silvopastoralism is a sustainable way of land management that reduces fire risk due to the reduction of fuel under trees when plants are used as animal food. This is particularly important in areas like Galicia that have 16% of the fired area of Europe. Silvopastoral systems can contribute to environment conservation and provide feed for autochthonous breeds more adapted to mountain conditions, enhancing biodiversity conservation. In formation on seasonal changes in crude protein content of spontaneous species will indicate better management of pasture resources in mountain areas