Alar Toomre: Difference between revisions
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| name = Alar Toomre | | name = Alar Toomre | ||
| alt = Alar Toomre | | alt = Alar Toomre | ||
| | | birth_date = {{birth year and age|1937}} | ||
| birth_place = Rakvere, Estonia | |||
| nationality = Estonian-American | |||
| fields = Applied mathematics, astrophysics, galactic dynamics | |||
| workplaces = Massachusetts Institute of Technology | |||
| alma_mater = Massachusetts Institute of Technology; University of Manchester | |||
| known_for = Toomre stability criterion (Q parameter); galaxy interactions and mergers; the Toomre sequence | |||
}} | }} | ||
'''Alar Toomre''' (born 5 February 1937) is an Estonian-American astrophysicist and applied mathematician, Professor Emeritus of Applied Mathematics at the Massachusetts Institute of Technology. He is best known for the Toomre stability criterion for differentially rotating discs and for pioneering computer simulations showing that the bridges and tails of interacting galaxies, and the formation of elliptical galaxies, can be explained by tidal encounters and mergers. | |||
==Biography== | |||
Toomre was born in Rakvere, Estonia. Following the Soviet occupation of Estonia in 1944 his family fled to Germany, and in 1949 they emigrated to the United States. He received his undergraduate degree in aeronautical engineering and physics from the Massachusetts Institute of Technology in 1957, and then studied at the University of Manchester as a Marshall Scholar, earning a Ph.D. in fluid mechanics. | |||
He returned to MIT as a C. L. E. Moore Instructor (1960-1962), spent a year at the Institute for Advanced Study in Princeton, and joined the MIT mathematics faculty in 1963. He was appointed Associate Professor in 1965 and Professor in 1970, and later became Professor Emeritus. He is also affiliated with the MIT Kavli Institute for Astrophysics and Space Research. | |||
His brother, Jüri Toomre, is also an astrophysicist, known for work in solar physics and helioseismology; the two collaborated on the galaxy-interaction simulations of the early 1970s. | |||
==Scientific contributions== | |||
In 1964 Toomre derived a local criterion for the gravitational stability of a differentially rotating disc of stars. The resulting dimensionless parameter, universally written as Q and known as the Toomre stability criterion, compares the stabilising effects of epicyclic (rotational) motion and random stellar velocity dispersion against the destabilising effect of the disc's surface density. It remains a standard diagnostic in studies of spiral structure, star formation and disc galaxy evolution. | |||
With Peter Goldreich he published work in 1969 on true polar wander, addressing the stability of a planet's rotation axis with respect to internal mass redistribution. | |||
In 1972 Toomre and his brother Jüri published "Galactic Bridges and Tails" in ''The Astrophysical Journal'', using restricted N-body computer simulations to demonstrate that the long tails and connecting bridges observed in peculiar galaxies are tidal features produced by close encounters between disc galaxies. The paper reproduced systems such as the Antennae Galaxies and Arp 295, and is regarded as a landmark in extragalactic astronomy. | |||
In 1977 Toomre proposed that many elliptical galaxies are the end products of mergers between spiral galaxies, and arranged a set of observed interacting systems into what became known as the Toomre sequence, an ordering of nearby merging pairs by their apparent stage of coalescence. The merger hypothesis is now a central element of galaxy formation theory. | |||
==Honors== | |||
* MacArthur Fellow (1984) | |||
* Fellow of the American Association for the Advancement of Science (1985) | |||
* Dirk Brouwer Award, Division on Dynamical Astronomy, American Astronomical Society | |||
* Magellanic Premium, American Philosophical Society (2014) | |||
* Member of the American Philosophical Society (2016) | |||
* Foreign member of the Estonian Academy of Sciences | |||
==External links== | |||
* [https://math.mit.edu/directory/profile.html?pid=277 MIT Department of Mathematics profile] | |||
* [https://www.space.mit.edu/people/alar-toomre/ MIT Kavli Institute profile] | |||
* [https://www.macfound.org/fellows/class-of-november-1984/alar-toomre MacArthur Foundation Fellow page] | |||
[[Category:Scientist|Toomre Alar]] | [[Category:Scientist|Toomre Alar]] | ||
[[Category:Worldwide List of Dissident Scientists]] | [[Category:Worldwide List of Dissident Scientists]] | ||
Latest revision as of 16:31, 20 July 2026
Alar Toomre | |
|---|---|
| Born | 1937 (age 88–89) Rakvere, Estonia |
| Nationality | Estonian-American |
| Alma mater | Massachusetts Institute of Technology; University of Manchester |
| Known for | Toomre stability criterion (Q parameter); galaxy interactions and mergers; the Toomre sequence |
| Scientific career | |
| Fields | Applied mathematics, astrophysics, galactic dynamics |
| Institutions | Massachusetts Institute of Technology |
Alar Toomre (born 5 February 1937) is an Estonian-American astrophysicist and applied mathematician, Professor Emeritus of Applied Mathematics at the Massachusetts Institute of Technology. He is best known for the Toomre stability criterion for differentially rotating discs and for pioneering computer simulations showing that the bridges and tails of interacting galaxies, and the formation of elliptical galaxies, can be explained by tidal encounters and mergers.
Biography
Toomre was born in Rakvere, Estonia. Following the Soviet occupation of Estonia in 1944 his family fled to Germany, and in 1949 they emigrated to the United States. He received his undergraduate degree in aeronautical engineering and physics from the Massachusetts Institute of Technology in 1957, and then studied at the University of Manchester as a Marshall Scholar, earning a Ph.D. in fluid mechanics.
He returned to MIT as a C. L. E. Moore Instructor (1960-1962), spent a year at the Institute for Advanced Study in Princeton, and joined the MIT mathematics faculty in 1963. He was appointed Associate Professor in 1965 and Professor in 1970, and later became Professor Emeritus. He is also affiliated with the MIT Kavli Institute for Astrophysics and Space Research.
His brother, Jüri Toomre, is also an astrophysicist, known for work in solar physics and helioseismology; the two collaborated on the galaxy-interaction simulations of the early 1970s.
Scientific contributions
In 1964 Toomre derived a local criterion for the gravitational stability of a differentially rotating disc of stars. The resulting dimensionless parameter, universally written as Q and known as the Toomre stability criterion, compares the stabilising effects of epicyclic (rotational) motion and random stellar velocity dispersion against the destabilising effect of the disc's surface density. It remains a standard diagnostic in studies of spiral structure, star formation and disc galaxy evolution.
With Peter Goldreich he published work in 1969 on true polar wander, addressing the stability of a planet's rotation axis with respect to internal mass redistribution.
In 1972 Toomre and his brother Jüri published "Galactic Bridges and Tails" in The Astrophysical Journal, using restricted N-body computer simulations to demonstrate that the long tails and connecting bridges observed in peculiar galaxies are tidal features produced by close encounters between disc galaxies. The paper reproduced systems such as the Antennae Galaxies and Arp 295, and is regarded as a landmark in extragalactic astronomy.
In 1977 Toomre proposed that many elliptical galaxies are the end products of mergers between spiral galaxies, and arranged a set of observed interacting systems into what became known as the Toomre sequence, an ordering of nearby merging pairs by their apparent stage of coalescence. The merger hypothesis is now a central element of galaxy formation theory.
Honors
- MacArthur Fellow (1984)
- Fellow of the American Association for the Advancement of Science (1985)
- Dirk Brouwer Award, Division on Dynamical Astronomy, American Astronomical Society
- Magellanic Premium, American Philosophical Society (2014)
- Member of the American Philosophical Society (2016)
- Foreign member of the Estonian Academy of Sciences