Stanford E. Woosley
Encyclopedia
Stanford Earl Woosley is a physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

, and Professor of Astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and Astrophysics
Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...

. He is the director of the Center for Supernova Research at UCSC
University of California, Santa Cruz
The University of California, Santa Cruz, also known as UC Santa Cruz or UCSC, is a public, collegiate university; one of ten campuses in the University of California...

. He has published over 300 papers.

Research Interest

Stan Woosley's research centers on theoretical high-energy astrophysics, especially violent explosive events such as supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

e and gamma ray burst
Gamma ray burst
Gamma-ray bursts are flashes of gamma rays associated with extremely energetic explosions that have been observed in distant galaxies. They are the most luminous electromagnetic events known to occur in the universe. Bursts can last from ten milliseconds to several minutes, although a typical...

s. A focus of interest is in the nucleosynthesis
Nucleosynthesis
Nucleosynthesis is the process of creating new atomic nuclei from pre-existing nucleons . It is thought that the primordial nucleons themselves were formed from the quark–gluon plasma from the Big Bang as it cooled below two trillion degrees...

, hydrodynamics
Fluid dynamics
In physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...

, and radiation transport of these events, and in the evolution
Stellar evolution
Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years to trillions of years .Stellar evolution is not studied by observing the life of a single...

 of massive star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

s, which sets the stage for such explosions.

Woosley is also co-investigator on the High Energy Transient Explorer-2
High Energy Transient Explorer
The High Energy Transient Explorer was an American astronomical satellite with international participation . The prime objective of HETE was to carry out the first multiwavelength study of gamma-ray bursts with UV, X-ray, and gamma-ray instruments mounted on a single, compact spacecraft...

--a satellite dedicated to the study of gamma-ray bursts, launched by NASA in 2000, and is involved in planning NASA's other missions for gamma-ray astronomy
Gamma-ray astronomy
Gamma-ray astronomy is the astronomical study of the cosmos with gamma rays. Gamma-rays are the most energetic form of "light" that travel across the universe, and gamma-rays thus have the smallest wavelength of any wave in the electromagnetic spectrum.Gamma-rays are created by celestial events...

.

His research projects include modeling the evolution of massive stars (8 to 50 times the mass of the sun) through all stages of nuclear burning, in an attempt to obtain realistic pre-supernova stars and a complete depiction of nucleosynthesis for all isotopes lighter than krypton. An example of this sort of work can be found in ApJS, 101, 181, (1995) with application to Galactic chemical evolution discussed in ApJS, 98, 617 (1995).

Woosley's work on the evolution of massive stars, which sets the stage for supernova explosions, helps explain how elements like oxygen and iron are formed, and more massive stars that produce a hypernova
Hypernova
Hypernova , also known as a type 1c Supernova, refers to an incredibly large star that collapses at the end of its lifespan...

. A supernova occurs when the core of a star collapses under the gravitational force of its own mass. The resulting explosion can be as bright as an entire galaxy, releasing immense amounts of energy. The explosion also spews into space all of the chemical elements forged by nuclear fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...

 reactions during the life of the star and some that are formed during the explosion itself. These materials may then contribute to the formation of new stars and planets. According to Woosley's collapsar model, gamma-ray bursts arise from the collapse of stars that are too massive to successfully explode as supernovae. Instead, they result in what has been termed a hypernova, which produce black hole
Black hole
A black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that...

s.

External links

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