NOAO >   Observing Info >   Approved Programs >   2009A-0227

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Proposal Information for 2009A-0227


PI: Andrea Dupree, Harvard-Smithsonian CfA, dupree@cfa.harvard.edu
Address: Solar, Stellar, Planetary Division, 60 Garden Street - MS 15, Cambridge, MA 02138, USA

CoI: Graeme Smith, Lick Observatory
CoI: Jay Strader, Harvard-Smithsonian CfA

Title: Fast Winds from Stars in M4

Abstract: Direct detection of winds from giant stars in globular clusters remains elusive although stellar evolution of low mass stars requires mass loss on the red giant branch in order to reproduce the horizontal branch morphology. The \ionHe1 1.0830\micron line observed in field metal-poor stars shows that fast (~100 km/s) winds occur in warm giants and also red horizontal branch stars in amounts with evolutionary significance. We propose to use PHOENIX to measure the \ionHe1 1.0830\micron line in giants and horizontal branch stars of the globular cluster M4 to detect fast mass outflows. Wind speeds may allow material to escape the cluster and solve the mystery of the missing interstellar medium in globular clusters. Non-LTE semi- empirical modeling of the winds based on these profiles combined with existing high resolution optical spectra, will establish stellar mass loss rates for metal-poor stars.


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NOAO >   Observing Info >   Approved Programs >   2009A-0227

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