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KITP: bs

By catdynamics on March 4, 2009.

we continue contemplation of stars going splat

there are blue stragglers in dwarf galaxies

they are presumably binaries merged through McCrea type I mass transfer

we're not sure exactly how that works in detail, but it must happen because we see it in progress - ie we see contact binaries on the main sequence which must eventually coalesce

if you look at the ratio of number of blue stragglers to some other stellar population, like horizontal branch stars, then the fraction of blue stragglers anti-correlates with the total luminosity of the parent dwarf galaxy

it is a weaker correlation then the one seen for clusters, which is presumably due to binary destruction, or lower binary fraction in high mass clusters. But it is there, about a factor of 3-10 over 10 magnitudes.

which is weird - some metallicity correlation with binarity?
Can't be a density effect, can it?

cf Momany et al

and Mapelli et al

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astro
KITP

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