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Found 3 talks width keyword late-type stars

Wednesday October 7, 2009

Rapid Temporal Survey (RaTS) - the search for ultra compact binaries

Armagh Observatory, UK

Abstract

Ultra Compact Binaries are predicted to be the strongest known sources of gravitational waves in the LISA pass-band. Since they are at the short period end of the orbital period distribution (<70 mins), their number is a sensitive test of binary evolutionary models. The best method to detect these short period systems, whose optical light is dominated by an accretion disk and show optical intensity variations on timescales close to their orbital period, is through deep, wide-field, fast-cadence photometric surveys. The RaTS (Rapid Temporal Survey) project is unique in that it is sensitive to variability on timescales as short as 2 mins and systems with V~22. Our strategy and initial results will be presented.

Archived in: Stars - Keywords:LISA, X-ray binaries, late-type stars, accretion, accretion discs

Abstract

Thursday October 30, 2008

Living with a red dwarf: X-ray and UV emissions of red dwarf stars and effects on hosted planets and their suitability for life

Villanova University, USA

Abstract

Red Dwarf (dM) stars are the most numerous stars in our Galaxy. These faint, cool, long-lived, and low mass stars make up > 80% of all stars in the Universe. Determining the number of red dwarfs with planets and assessing planetary habitability (a planet’s potential to develop and sustain life) are critically important because such studies would indicate how common life is in the universe. Our program - "Living with a Red Dwarf" addresses these questions by investigating the long-term nuclear evolution and magnetic-dynamo coronal and chromospheric X-ray to Ultraviolet properties of red dwarf stars with widely different ages. The major focus of the program is to study the magnetic-dynamo generated X-ray-Ultraviolet emissions and flare properties of red dwarf stars from youth to old age. Emphasized are how the stellar X-UV emissions, flares & winds affect hosted planets and impact their habitability. We have developed age-rotation-activity relations and also are constructing irradiance tables (X-UV fluxes) that can be used to model the effects of X-UV radiation on planetary atmospheres and on possible life on nearby hosted planets. Despite the earlier pessimistic view that red dwarfs stars are not suitable for habitable planets - mainly because their low luminosities require a hosted planet to orbit quite close (r <0.3 AU) to be sufficiently warm to support life. Our initial results indicate that red dwarf stars (in particular the warmer dM stars) can indeed be suitable hosts for habitable planets capable of sustaining life for hundreds of billion years. Some examples of red dwarf stars currently known to host planets are discussed.

Archived in: Stars, Planetary systems - Keywords:subdwarfs, stellar evolution, late-type stars, exoplanets

Abstract

Tuesday April 29, 2008

Radiation-hydrodynamical model atmospheres across the Hertzsprung-Russell diagram

Observatoire de Paris-Meudon, France

Abstract

In the EU funded Marie Curie Excellence Team CIFIST (Cosmological Impact of the FIrst STars) work is under way to construct 3D radiation-hydrodynamical model atmospheres for late-type dwarfs and giants, in particular of low metallicity. I will present an overview of the present state of the efforts, discuss some applications of the models, and point to necessary future developments.

Archived in: Stars, Particle astrophysics, physical data and processes - Keywords:late-type stars, radiative transfer, hydrodynamics

Abstract

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