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An appraisal of the behavior of stellar entropy along stellar evolution is made. It is shown that the entropy per baryon of a star of a fixed baryon number decreases monotonically with increasing compactness of the star. The same entropy per baryon increases only whenever an irreversible collapse of the star happens. The recent proposals for a gravitational entropy related to curvature may justify the huge increase of the entropy in the ultimate collapse to a black hole.

Based on astrophysical constraints derived from Chandrasekhar's mass limit for white-dwarfs, we study the effects of the model on the parameters of unparticle-inspired gravity, on scales ΛU > 1 T eV and dU ≈ 1.

31Isoprene fluxes vary seasonally with changes in environmental factors (e.g., solar 32 radiation and temperature) and biological factors (e.g., leaf phenology). However, our 33 understanding of seasonal patterns of isoprene fluxes and associated mechanistic controls 34 are still limited, especially in Amazonian evergreen forests. In this paper, we aim to 35 connect intensive, field-based measurements of canopy isoprene flux over a central 36Amazonian evergreen forest with meteorological observations and with tower-camera 37 leaf phenology to improve understanding of patterns and causes of isoprene flux 38seasonality. Our results demonstrate that the highest isoprene emissions are observed 39 during the dry and dry-to-wet transition seasons, whereas the lowest emissions were 40 found during the wet-to-dry transition season. Our results also indicate that light and 41 temperature can not totally explain the isoprene flux seasonality. Instead, the camera-42 derived leaf area index (LAI) of recently mature leaf-age class (e.g. leaf ages of 3-5 43 months) exhibits the highest correlation with observed isoprene flux seasonality 44

We revisit the present status of the stiffness of the supranuclear equations of state, particularly the solutions that increase the stiffness in the presence of hyperons, the putative transition to a quark matter phase and the robustness of massive compact star observations.

We study in this work the evolution of the magnetic field in 'redback-black widow' pulsars. Evolutionary calculations of these 'spider' systems suggest that first the accretion operates in the redback stage, and later the companion star ablates matter due to winds from the recycled pulsar. It is generally believed that mass accretion by the pulsar results in a rapid decay of the magnetic field when compared to the rate of an isolated neutron star. We study the evolution of the magnetic field in black widow pulsars by solving numerically the induction equation using the modified Crank-Nicolson method with intermittent episodes of mass accretion on to the neutron star. Our results show that the magnetic field does not fall below a minimum value ('bottom field') in spite of the long evolution time of the black widow systems, extending the previous conclusions for much younger low-mass X-ray binary systems. We find that in this scenario, the magnetic field decay is dominated by the accretion rate, and that the existence of a bottom field is likely related to the fact that the surface temperature of the pulsar does not decay as predicted by the current cooling models. We also observe that the impurity of the pulsar crust is not a dominant factor in the decay of magnetic field for the long evolution time of black widow systems.

This paper is devoted to discuss the difference in the thermodynamic entropy budget per baryon in each type of stellar object found in Universe. We track and discuss the actual decrease of the stored baryonic thermodynamic entropy from the most primitive molecular cloud up to the final fate of matter in the black holes, passing through evolved states of matter as found in white dwarfs and neutron stars. We then discuss the case of actual stars of different masses throughout their evolution, clarifying the role of virial equilibrium condition for the decrease of the entropy and related issues. Finally, we discuss how gravity ultimately drives composition, hence structural changes along the stellar evolution all the way until the ultimate collapse to black holes, which may increase dramatically their entropy because of the gravitational contribution itself.

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