Massive stars: stellar models and stellar yields, impact on Galactic Archaeology

The physics of massive stars depends (at least) on convection, mass loss by stellar winds, rotation, magnetic fields and multiplicity. We briefly discuss the impact of the first three processes on the stellar yields trying to identify some guidelines for future works.Comment: 8 pages, 6 figures, in press for the proceedings of IAU Symposium 334, Rediscovering our Galaxy, C. Chiappini, I. Minchev, E. Starkenburg, M. Valentini ed

Star-planet interactions. IV. Possibility of detecting the orbit-shrinking of a planet around a red giant

The surface rotations of some red giants are so fast that they must have been spun up by tidal interaction with a close companion, either another star, a brown dwarf, or a planet. We focus here on the case of red giants that are spun up by tidal interaction with a planet. When the distance between the planet and the star decreases, the spin period of the star decreases, the orbital period of the planet decreases, and the reflex motion of the star increases. We study the change rate of these three quantities when the circular orbit of a planet of 15 M$_{J}$ that initially orbits a 2 M$_\odot$ star at 1 au shrinks under the action of tidal forces during the red giant phase. We use stellar evolution models coupled with computations of the orbital evolution of the planet, which allows us to follow the exchanges of angular momentum between the star and the orbit in a consistent way. We obtain that the reflex motion of the red giant star increases by more than 1 m s$^{-1}$ per year in the last $\sim$40 years before the planet engulfment. During this phase, the reflex motion of the star is between 660 and 710 m s$^{-1}$. The spin period of the star increases by more than about 10 minutes per year in the last 3000 y before engulfment. During this period, the spin period of the star is shorter than 0.7 year. During this same period, the variation in orbital period, which is shorter than 0.18 year, is on the same order of magnitude. Changes in reflex-motion and spin velocities are very small and thus most likely out of reach of being observed. The most promising way of detecting this effect is through observations of transiting planets, that is, through{\it } changes of the beginning or end of the transit. A space mission like PLATO might be of great interest for detecting planets that are on the verge of being engulfed by red giants.Comment: 4 pages, 4 figure

Breathlessness in the elderly during the last year of life sufficient to restrict activity

OBJECTIVES: Breathlessness is prevalent in older people. Symptom control at the end of life is important. This study investigated relationships between age, clinical characteristics and breathlessness sufficient to have people spend at least one half a day in that month in bed or cut down on their usual activities (restricting breathlessness) during the last year of life. DESIGN: Secondary data-analysis SETTING: General community PARTICIPANTS: 754 non-disabled persons, aged 70 and older. Monthly telephone interviews were conducted to determine the occurrence of restricting breathlessness. The primary outcome was the percentage of months with restricting breathlessness reported during the last year of life. RESULTS: Data regarding breathlessness were available for 548/589 (93.0%) decedents (mean age 86.7 years (range 71 to 106; males 38.8%). 311/548 (56.8%) reported restricting breathlessness at some time-point during the last year of life but no-one reported this every month. Frequency increased in the months closer to death irrespective of cause. Restricting breathlessness was associated with anxiety, (0.25 percentage point increase in months breathlessness per percentage point months reported anxiety, 95% CI 0.16 to 0.34, P<0.001), depression (0.14, 0.05 to 0.24, P=0.002) and mobility problems (0.07, 0.03 to 0.1, P=0.001). Percentage months of restricting breathlessness increased if chronic lung disease was noted at the most recent comprehensive assessment (6.62 percentage points, 95% CI 4.31 to 8.94, P<0.001), heart failure (3.34, 0.71 to 5.97, P<0.01), and ex-smoker status (3.01, 0.94 to 5.07, P=0.002), but decreased with older age (─0.19, ─0.37 to ─0.02, P=0.03). CONCLUSION: Restricting breathlessness increased in this elderly population in the months preceding death from any cause. Breathlessness should be assessed and managed in the context of poor prognosis

Imagination links with schizotypal beliefs, not with creativity or learning

Imagination refers to creating mental representations of concepts, ideas, and sensations that are not contemporaneously perceived by the senses. Although it is key to human individuality, research on imagination is scarce. To address this gap, we developed here a new psychometric test to assess individual differences in imagination and explored the role of imagination for learning, creativity, and schizotypal beliefs. In a laboratory-based (N = 180) and an online study (N = 128), we found that imagination is only weakly associated with learning achievement and creativity, accounting for 2–8% of the variance. By contrast, imagination accounted for 22.5% of the variance in schizotypal beliefs, suggesting overall that imagination may be more indicative of cognitive eccentricities rather than benefit the accumulation of knowledge or production of novel and useful ideas

Grids of stellar models with rotation IV. Models from 1.7 to 120 M-circle dot at a metallicity Z=0.0004

The effects of rotation on stellar evolution are particularly important at low metallicity, when mass loss by stellar winds diminishes and the surface enrichment due to rotational mixing becomes relatively more pronounced than at high metallicities. Here we investigate the impact of rotation and metallicity on stellar evolution. Using similar physics as in our previous large grids of models at Z = 0.002 and Z = 0.014, we compute stellar evolution models with the Geneva code for rotating and nonrotating stars with initial masses (Mini) between 1.7 and 120 M⊙ and Z = 0.0004 (1/35 solar). This is comparable to the metallicities of the most metal poor galaxies observed so far, such as I Zw 18. Concerning massive stars, both rotating and nonrotating models spend most of their core-helium burning phase with an effective temperature higher than 8000 K. Stars become red supergiants only at the end of their lifetimes, and few red supergiants are expected. Our models predict very few to no classical Wolf–Rayet stars as a results of weak stellar winds at low metallicity. The most massive stars end their lifetimes as luminous blue supergiants or luminous blue variables, a feature that is not predicted by models with higher initial metallicities. Interestingly, due to the behavior of the intermediate convective zone, the mass domain of stars producing pair-instability supernovae is smaller at Z = 0.0004 than at Z = 0.002. We find that during the main sequence (MS) phase, the ratio between nitrogen and carbon abundances (N/C) remains unchanged for nonrotating models. However, N/C increases by factors of 10–20 in rotating models at the end of the MS. Cepheids coming from stars with Mini >  4 − 6 M⊙ are beyond the core helium burning phase and spend little time in the instability strip. Since they would evolve towards cooler effective temperatures, these Cepheids should show an increase of the pulsation period as a function of age

Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process.Comment: 10 pages, 14MB, accepted by FAIR STI in May 2009, editors: Inti Lehmann (chair), Andrea Bersani, Yuri Lobanov, Jost Luehning, Jerzy Smyrski, Technical Coordiantor: Lars Schmitt, Bernd Lewandowski (deputy), Spokespersons: Ulrich Wiedner, Paola Gianotti (deputy

Physics Performance Report for PANDA: Strong Interaction Studies with Antiprotons

To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with nucleons and nuclei, the universal PANDA detector will be built. Gluonic excitations, the physics of strange and charm quarks and nucleon structure studies will be performed with unprecedented accuracy thereby allowing high-precision tests of the strong interaction. The proposed PANDA detector is a state-of-the art internal target detector at the HESR at FAIR allowing the detection and identification of neutral and charged particles generated within the relevant angular and energy range. This report presents a summary of the physics accessible at PANDA and what performance can be expected.Comment: 216 page