Alar Toomre
Encyclopedia
Alar Toomre is an Estonian
-born astronomer
and mathematician
who immigrated to the United States in 1949. He is a professor of applied mathematics
at the Massachusetts Institute of Technology
. Toomre's research is focused on the dynamics of galaxies.
on a Marshall Scholarship
where he obtained a Ph.D. in fluid dynamics.
Toomre returned to MIT to teach after completing his Ph.D. and remained there for two years. After spending a year at Princeton University
, he returned again to MIT as part of the faculty, where he stayed. Toomre was appointed an Associate Professor of Mathematics at MIT in 1965, and Professor in 1970.
In 1964 Toomre devised an instability criterion for differentially rotating disks now known as the Toomre instability. Alternatively, it may be expressed as Toomre's stability criterion which is usually measured with the parameter Q.
Toomre collaborated with Peter Goldreich
in 1969 on the subject of polar wander
, developing the theory of polar wander. Whether true polar wander
has been observed on earth, or apparent polar wander
is accountable for all the observations of paleomagnetism
remains a controversial issue.
Toomre conducted the first computer simulations
of galaxy merger
s in the 1970s with his brother Jüri Toomre. Although the small number of particles in the simulations obscured many processes in galactic collisions, Toomre and Toomre were able to identify tidal tail
s in his simulations, similar to those seen in the Antennae Galaxies
and the Mice
. 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. In 1977 Toomre suggested that elliptical galaxies
are the remnants of the major mergers of spiral galaxies
. He further showed that based on the local galaxy merger rate, over a Hubble time the observed number of elliptical galaxies are produced if the universe begins with only spiral galaxies. This idea remained controversial and widely debated for some time.
From this work, the Toomre brothers identified the process of collision evolution as the Toomre sequence. The sequence begins with two well separated spiral galaxies and follows them through collisional disruption until they settle into a single elliptical galaxy.
which recognizes "outstanding contributions to the field of Dynamical Astronomy".
Toomre was one of the 1984 recipients of the MacArthur Fellowship, popularly known as the "Genius Grant".
Estonians
Estonians are a Finnic people closely related to the Finns and inhabiting, primarily, the country of Estonia. They speak a Finnic language known as Estonian...
-born astronomer
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
and mathematician
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
who immigrated to the United States in 1949. He is a professor of applied mathematics
Applied mathematics
Applied mathematics is a branch of mathematics that concerns itself with mathematical methods that are typically used in science, engineering, business, and industry. Thus, "applied mathematics" is a mathematical science with specialized knowledge...
at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
. Toomre's research is focused on the dynamics of galaxies.
Career
Toomre received an undergraduate degree in Aeronautical Engineering and Physics from MIT in 1957 and then studied at the University of ManchesterUniversity of Manchester
The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...
on a Marshall Scholarship
Marshall Scholarship
The Marshall Scholarship, a postgraduate scholarships available to Americans, was created by the Parliament of the United Kingdom when the Marshall Aid Commemoration Act was passed in 1953. The scholarships serve as a living gift to the United States of America in recognition of the post-World War...
where he obtained a Ph.D. in fluid dynamics.
Toomre returned to MIT to teach after completing his Ph.D. and remained there for two years. After spending a year at Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
, he returned again to MIT as part of the faculty, where he stayed. Toomre was appointed an Associate Professor of Mathematics at MIT in 1965, and Professor in 1970.
Scientific accomplishments
Toomre collaborated with Peter Goldreich
Peter Goldreich
Peter Goldreich is an American astrophysicist whose research focuses on celestial mechanics, planetary rings, helioseismology and neutron stars. He is currently the Lee DuBridge Professor of Astrophysics and Planetary Physics at California Institute of Technology. Since 2005 he has also been a...
in 1969 on the subject of polar wander
Polar wander
Polar wander is the movement of the North and South Poles of the Earth with respect to the continents. This motion can be divided into two components: that due to continental drift , and true polar wander, in which the mantle and the crust rotate together into new orientations....
, developing the theory of polar wander. Whether true polar wander
True polar wander
True polar wander is a solid-body rotation of a planet or moon with respect to its spin axis, causing the geographic locations of the North and South Poles to change, or "wander". In a stable state, the largest moments of inertia axis is aligned with the spin axis, with the smaller two moment of...
has been observed on earth, or apparent polar wander
Apparent polar wander
Apparent polar wander is the imaginary movement of the Earth's magnetic poles relative to a continent while regarding the continent being studied as fixed in position, as determined by paleomagnetic data...
is accountable for all the observations of paleomagnetism
Paleomagnetism
Paleomagnetism is the study of the record of the Earth's magnetic field in rocks. Certain minerals in rocks lock-in a record of the direction and intensity of the magnetic field when they form. This record provides information on the past behavior of Earth's magnetic field and the past location of...
remains a controversial issue.
Galactic Bridges and Tails (1971 film)
Galactic Bridges and Tails is a computer animation film created by astrophysicists Alar Toomre and . The brothers created the film as a teaching aid for their landmark research paper of the same name, published in The Astrophysical Journal, detailing the collision of galaxies or galaxy mergers.-...
of galaxy merger
Galaxy merger
Galaxy mergers can occur when two galaxies collide. They are the most violent type of galaxy interaction. Although galaxy mergers do not involve stars or star systems actually colliding, due to the vast distances between stars in most circumstances, the gravitational interactions between galaxies...
s in the 1970s with his brother Jüri Toomre. Although the small number of particles in the simulations obscured many processes in galactic collisions, Toomre and Toomre were able to identify tidal tail
Tidal tail
A tidal tail is a thin, elongated region of stars and interstellar gas that extends into space from a galaxy. Tidal tails occur as a result of galactic tide forces between interacting galaxies. Examples of galaxies with tidal tails include the Tadpole Galaxy and the Mice Galaxies...
s in his simulations, similar to those seen in the Antennae Galaxies
Antennae Galaxies
The Antennae Galaxies are a pair of interacting galaxies in the constellation Corvus. They are currently going through a phase of starburst. They were discovered by William Herschel in 1785...
and the Mice
Mice Galaxies
NGC 4676, or the Mice Galaxies, are two spiral galaxies in the constellation Coma Berenices. About 290 million light-years away, they are presently in the process of colliding and merging...
. 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. In 1977 Toomre suggested that elliptical galaxies
Elliptical galaxy
An elliptical galaxy is a galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile. They range in shape from nearly spherical to highly flat and in size from hundreds of millions to over one trillion stars...
are the remnants of the major mergers of spiral galaxies
Spiral galaxy
A spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as...
. He further showed that based on the local galaxy merger rate, over a Hubble time the observed number of elliptical galaxies are produced if the universe begins with only spiral galaxies. This idea remained controversial and widely debated for some time.
From this work, the Toomre brothers identified the process of collision evolution as the Toomre sequence. The sequence begins with two well separated spiral galaxies and follows them through collisional disruption until they settle into a single elliptical galaxy.
Awards and honors
In 1993, Toomre received the Dirk Brouwer AwardBrouwer Award (Division on Dynamical Astronomy)
The Dirk Brouwer Award, usually known as the Brouwer Award, is awarded annually by the Division on Dynamical Astronomy of the American Astronomical Society for outstanding lifetime achievement in the field of dynamical astronomy...
which recognizes "outstanding contributions to the field of Dynamical Astronomy".
Toomre was one of the 1984 recipients of the MacArthur Fellowship, popularly known as the "Genius Grant".