Toomre returned to MIT to teach after completing his Ph.D. and remained there for two years.[5] After spending a year at theInstitute for Advanced Study,[7] he returned again to MIT as part of the faculty, where he stayed.[5] Toomre was appointed an Associate Professor of Mathematics at MIT in 1965, and Professor in 1970.[7]
The results of the Toomre brothers' simulations of the Antennae Galaxies
In 1964, Toomre devised a local gravitational stability criterion for differentially rotating disks.[8] It is known as theToomre stability criterion, which is usually measured by a parameter denoted asQ.[9] TheQ parameter measures the relativeimportance of vorticity and internal velocity dispersion (large values of which stabilise) versus the disk surface density (large values of which destabilise). The parameter is constructed so thatQ<1 implies instability.
The Antennae Galaxies by Brad Whitmore (STScI), andNASA
Toomre conducted the first computersimulations ofgalaxy mergers in the 1970s with his brother Jüri, an astrophysicist and solar physicist.[12][13] Although the small number of particles in the simulations obscured many processes in galactic collisions, Toomre and Toomre were able to identifytidal tails in his simulations, similar to those seen in theAntennae Galaxies andthe Mice.[14][15][16] The brothers attempted to reproduce specific galaxy mergers in their simulations, and it was their reproduction of the Antennae galaxies that gave them the greatest pleasure.[17] In 1977 Toomre suggested thatelliptical galaxies are the remnants of themajor mergers ofspiral galaxies.[18][19] He further showed that based on the local galaxy merger rate, over aHubble time the observed number of elliptical galaxies are produced if the universe begins with only spiral galaxies.[20] This idea remained controversial and widely debated for some time.[21][22]
From this work, the Toomre brothers identified the process of collision evolution as theToomre sequence.[23][24] The sequence begins with two well separated spiral galaxies and follows them (as for theAntennae) through collisional disruption until they settle into a single elliptical galaxy.[25]
^V. Courtillot (Fall 2004). "A Short Review of True Polar Wander".AGU Fall Meeting Abstracts.31: U31B–08.Bibcode:2004AGUFM.U31B..08C. abstract #U31B-08
^"The DDA/AAS Brouwer Award". American Astronomical Society/Division on Dynamical Astronomy.Archived from the original on 13 May 2007. Retrieved2007-05-18.
