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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2836
DTSTART:20121018T203000Z
DURATION:PT1H0M0S
DTSTAMP:20260420T034651Z
LAST-MODIFIED:20121015T210901Z
LOCATION:4421 Sterling Hall
SUMMARY:Blue Straggler Formation in the Old Open Cluster NGC188\, Astr
 onomy Colloquium\, Aaron Geller\, Northwestern University
DESCRIPTION:<br><br>
\n<br><br>
\nOpen clusters occupy a compelling re
 gime for blue straggler formation.  Their moderate stellar densities p
 ermit blue straggler formation through all of the known mechanisms\, n
 amely collisions\, mergers and mass transfer.  Furthermore\, the acces
 sibility of open clusters to both detailed observations and sophistica
 ted N-body simulations provides unique opportunities to investigate th
 e origins of blue stragglers in great detail.  Perhaps the most well-s
 tudied blue straggler population in an open cluster is that of NGC 188
 .  This ~7 Gyr open cluster hosts 21 blue stragglers\, 16 of which are
  known to have binary companions\, as revealed by our multi-epoch WIYN
 /Hydra radial-velocity survey.  The majority of these blue stragglers 
 have ~0.5 Msun companions that orbit with periods of order 1000 days a
 nd have modest eccentricities. Comparisons with predictions from N-bod
 y simulations of NGC 188 show that collisions and mergers cannot creat
 e such blue stragglers. (Although these mechanisms may account for som
 e or all of the other blue stragglers in the cluster.) Instead the dom
 inant formation mechanism for the blue stragglers in NGC 188 is most l
 ikely mass transfer processes.<br><br>
\n
URL:https://www.physics.wisc.edu/events/?id=2836
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