= Alar Toomre
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<Alar Toomre> connected the stability of a stellar <galactic disk> to the competition between <self-gravity>, rotation and random stellar <motion>. His 1964 analysis gave a local axisymmetric stability criterion, commonly expressed through the <Toomre parameter>. A dynamically cold disk can be more vulnerable to gravitational structure formation than one with larger <velocity dispersion>.<On the Gravitational Stability of a Disk of Stars by Alar Toomre>[p. 1217, abstract and local stability problem]{ref}
With <Juri Toomre>, he also modeled the tidal bridges and tails of interacting <galaxies>. Their test-particle encounters showed how <gravity> alone can draw long structures out of rotating <galactic disks>.<Galactic Bridges and Tails by Alar Toomre and Juri Toomre>[p. 623, abstract and model assumptions]{ref}
\Image[https://commons.wikimedia.org/wiki/Special:Redirect/file/Alar_Toomre.jpg?width=260]
{title=Portrait of <Alar Toomre>}
{description=Via Wikimedia Commons; credits and usage information are on the linked source file page.}
{source=https://commons.wikimedia.org/wiki/File:Alar_Toomre.jpg}
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