The warm circumstellar envelope and wind of the G9 IIb star HR 6902

IUE observations of the eclipsing binary system HR 6902 obtained at various epochs spread over four years indicate the presence of warm circumstellar material enveloping the G9 IIb primary. The spectra show Si IV and C IV absorption up to a distance of 3.3 giant radii (R_g}. Line ratio diagnostics yields an electron temperature of ~ 78000 K which appears to be constant over the observed height range. Applying a least square fit absorption line analysis we derive column densities as a function of height. We find that the inner envelope (< 3 R_g) of the bright giant is consistent with a hydrostatic density distribution. The derived line broadening velocity of ~ 70 kms^{-1} is sufficient to provide turbulent pressure support for the required scale height. However, an improved agreement with observations over the whole height regime including the emission line region is obtained with an outflow model. We demonstrate that the common beta power-law as well as a P \propto rho wind yield appropriate fit models. Adopting a continuous mass outflow we obtain a mass-loss rate of M_loss= (0.8 - 3.4)*10^{-11} M_{sun}yr^{-1} depending on the particular wind model.Comment: 11 pages, 8 figures, submitted to Astronomy Astrophysics main Journa

A Review of Bondi--Hoyle--Lyttleton Accretion

If a point mass moves through a uniform gas cloud, at what rate does it accrete material? This is the question studied by Bondi, Hoyle and Lyttleton. This paper draws together the work performed in this area since the problem was first studied. Time has shown that, despite the simplifications made, Bondi, Hoyle and Lyttleton made quite accurate predictions for the accretion rate. Bondi--Hoyle--Lyttleton accretion has found application in many fields of astronomy, and these are also discussed.Comment: 25 pages Accepted by New Astronomy Reviews Revision corrects a rather important typo about timescales in the stability sectio

INSPIRE: Support for and requirement of the Marine Strategy Framework Directive

This paper documents how to apply INSPIRE Directive 2007/2/EC principles for efficient implementation of the Marine Strategy Framework Directive 2008/56/EC (MSFD). It provides an overview of the different INSPIRE components, explains the relationship between the MSFD requirements and improves the understanding of distributed data management. The MSFD reporting cycle is analyzed in detail, identifying spatial data requirements and mapping them into the INSPIRE implementation roadmap. The study comprises a thorough analysis on MSFD requirements of data & information sharing from the initial assessment and monitoring programmes, applying INSPIRE data management.</p

INSPIRE: support for and requirement of the Marine Strategy Framework Directive

This paper documents how to apply INSPIRE Directive 2007/2/EC principles for efficient implementation of the Marine Strategy Framework Directive 2008/56/EC (MSFD). It provides an overview of the different INSPIRE components, explains the relationship between the MSFD requirements and improves the understanding of distributed data management. The MSFD reporting cycle is analysed in detail, identifying spatial data requirements and mapping them into the INSPIRE implementation roadmap. The study comprises a thorough analysis on MSFD requirements of data & information sharing from the initial assessment and monitoring programmes, applying INSPIRE data management.JRC.I.1-Monitoring, Indicators & Impact Evaluatio