\def\kms{km s$^{-1}$}

<HEADER><TITLE>Rotational Velocities for Blue Horizontal Branch Stars in Globular Clusters</TITLE>

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<DL><DT><B>Session 50 -- Globular Clusters</B>

<DT><I>Display presentation, Wednesday, 9:20-6:30, Pauley Room</I>

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<H2>[50.03] Rotational Velocities for Blue Horizontal Branch Stars in Globular Clusters</H2>

<I>Ruth C. Peterson (UCO/Lick), Deborah A. Crocker (UAlabama), Robert T. Rood (UVa)</I>

<P>Rotational velocities $v \sin i$ are derived for two dozen stars in each of the

globular clusters M3, M13, and NGC 288.  Rotation is most prevalent in M13:

most stars are rotating more rapidly than 20 \kms, and a half dozen more

rapidly than 30 \kms.  In M3, only a few are rotating more rapidly than 20 \kms,

and none reach this level in NGC 288.  We illustrate our method of determining

$v \sin i$ from fits to a grid of synthetic spectra, present the results

for the stars observed in each cluster, and discuss the distribution of

$v \sin i$ values and their ramifications for stellar evolution and

the appearance of the globular-cluster color-magnitude diagram.



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