Dr. Sun Hong Rhie (1 March 1955 – 14 October 2013) was a Korean–American astrophysicist best known for her foundational contributions to the theory of

gravitational microlensing Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers ...

, a technique for the discovery of

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

Early life

Rhie was born to Lee Sin Woo and Kim Soon Im on 1 March 1955, near Chiri Mountain in Gurae,

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...

. The family later moved to the city of

Gwangju Gwangju () is South Korea's sixth-largest metropolis. It is a designated metropolitan city under the direct control of the central government's Home Minister. The city was also the capital of South Jeolla Province until the provincial office ...

for her father's job as a school principal.

Education

She achieved national notoriety for being the top-scoring girl in South Korea in that year's national pre-entrance exams. She attended

Seoul National University Seoul National University (SNU; ) is a national public research university located in Seoul, South Korea. Founded in 1946, Seoul National University is largely considered the most prestigious university in South Korea; it is one of the three "S ...

, where she received her

bachelor's degree A bachelor's degree (from Middle Latin ''baccalaureus'') or baccalaureate (from Modern Latin ''baccalaureatus'') is an undergraduate academic degree awarded by colleges and universities upon completion of a course of study lasting three to six ...

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

in 1978. Rhie moved to the United States for her graduate work and received a

master's degree A master's degree (from Latin ) is an academic degree awarded by universities or colleges upon completion of a course of study demonstrating mastery or a high-order overview of a specific field of study or area of professional practice.

in physics from

UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California St ...

in 1982. She then transferred to

Stanford University Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is consider ...

, where in 1988 she received her PhD with a thesis on heavy fourth-generation

neutrino A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...

s, supervised by

Fred Gilman Frederick Joseph Gilman is an American physicist and the Buhl Professor of Theoretical Physics Emeritus at Carnegie Mellon University. Early life and education Gilman was born on October 9, 1940. He grew up in East Lansing, Michigan and receiv ...

. She followed this in 1990 with postdoc positions at the

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...

, and

Lawrence Livermore National Laboratory Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...

. She became a

research professor Professor (commonly abbreviated as Prof.) is an academic rank at universities and other post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin as a "person who professes". Professors ...

in the department of physics at the

University of Notre Dame The University of Notre Dame du Lac, known simply as Notre Dame ( ) or ND, is a private Catholic research university in Notre Dame, Indiana, outside the city of South Bend. French priest Edward Sorin founded the school in 1842. The main campu ...

, where she conducted her most prominent research.

Contributions to gravitational microlensing

When the first gravitational microlensing event, MACHO-LMC-1, was discovered in 1993, Rhie noticed that the light curve had a feature that could be explained by a planetary companion. This was noted by astronomer Phil Yock: "It was at one of these early meetings, probably the 1995 one, that Sun said to me that the first microlensing event found by the MACHO group, the one in the LMC that was shown on the cover of Nature, could include a planet." Along with her husband David Bennett, Rhie developed the first planetary microlensing light-curve code, including finite source effects, that enabled the modeling of planetary microlensing light curves. This discovery, and the prompt detection of such events with the

MACHO Machismo (; ; ; ) is the sense of being " manly" and self-reliant, a concept associated with "a strong sense of masculine pride: an exaggerated masculinity". Machismo is a term originating in the early 1930s and 1940s best defined as hav ...

survey, led to the proposal to NASA of a mission concept that would become known as the Microlensing Planet Finder. Eventually its exoplanet measurement capabilities were combined with similar

cosmology Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount (lexicographer), Thomas Blount's ''Glossographia'', and in 1731 taken up in ...

capabilities that were subsumed into the

Nancy Grace Roman Space Telescope The Nancy Grace Roman Space Telescope (shortened as Roman or the Roman Space Telescope, and formerly the Wide-Field Infrared Survey Telescope or WFIRST) is a NASA infrared space telescope currently in development and scheduled to launch by Ma ...

. In 1999, the technique was used to discover the first planet orbiting a binary star. Her most noteworthy work was her 2003 demonstration, through an elegant perturbation argument, that a

lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...

system of ''N≥2'' point masses can have 5(''N'' − 1) images. The problem is equivalent to a pure analytical question in mathematics concerning the number of zeros of the rational

harmonic function In mathematics, mathematical physics and the theory of stochastic processes, a harmonic function is a twice continuously differentiable function f: U \to \mathbb R, where is an open subset of that satisfies Laplace's equation, that is, : \f ...

of degree ''N:''

f(z)=p(z)/q(z)-\bar

. The result was considered so noteworthy in pure mathematics, it warranted a 2008 review article in the ''Notices of the American Mathematical Society.''

Personal life

She was married to astrophysicist David Bennett and has a daughter. In her later years, Rhie was diagnosed with

schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social withdra ...

, limited her ability to continue her research; unable to tolerate the refereeing of her papers, much of her work is published only at

arXiv arXiv (pronounced "archive"—the X represents the Greek letter chi ⟨χ⟩) is an open-access repository of electronic preprints and postprints (known as e-prints) approved for posting after moderation, but not peer review. It consists of ...

.org.

References

External links

Sun Hong Rhie memorial page at Notre Dame

Obituary in Physics Today

Session of Microlensing 18 meeting devoted to Rhie
{{Authority control University of California, Los Angeles alumni Women astrophysicists Seoul National University alumni Stanford University alumni 1955 births 2013 deaths People with schizophrenia