Johannes A. van Paradijs (9 June 1946 – 2 November 1999) was a Dutch high-energy astrophysicist. He is best known for discovering the first optical afterglow of a

gamma-ray burst In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten milli ...

, GRB 970228, in February 1997, together with two of his students, and for establishing that gamma-ray bursts are extragalactic events. He was married to the astrophysicist Chryssa Kouveliotou.

Research

Van Paradijs determined the first mass of a

neutron star A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. w ...

, the

X-ray pulsar X-ray pulsars or accretion-powered pulsars are a class of astronomical objects that are X-ray sources displaying strict periodic variations in X-ray intensity. The X-ray periods range from as little as a fraction of a second to as much as several m ...

Vela X-1 Vela or Velas may refer to: Astronomy * Vela (constellation), a constellation in the southern sky (the Sails) ** Vela (Chinese astronomy) ** Vela Pulsar ** Vela X-1, a pulsing, eclipsing high-mass X-ray binary system Places *Vela Bluff, Ant ...

in 1975. In 1978 he showed that

X-ray burster X-ray bursters are one class of X-ray binary stars exhibiting X-ray bursts, periodic and rapid increases in luminosity (typically a factor of 10 or greater) that peak in the X-ray region of the electromagnetic spectrum. These astrophysical syst ...

s are neutron stars in

binary system A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter ''(also see Barycenter#Gallery, animated examples)''. More restrictive definitio ...

s. Using

spectroscopic Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter ...

mapping, he was the first to spatially resolve an

accretion disk An accretion disk is a structure (often a circumstellar disk) formed by diffuse material in orbital motion around a massive central body. The central body is typically a star. Friction, uneven irradiance, magnetohydrodynamic effects, and other ...

Academic career

Van Paradijs obtained his PhD at the

University of Amsterdam The University of Amsterdam (abbreviated as UvA, nl, Universiteit van Amsterdam) is a public research university located in Amsterdam, Netherlands. The UvA is one of two large, publicly funded research universities in the city, the other bein ...

, Netherlands, in 1975, working on cool

giant star A giant star is a star with substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press ...

s. His thesis was entitled "Studies of line spectra of G- and K-type stars" and his supervisor was David Koelbloed. Afterwards he started working on

X-ray binaries X-ray binaries are a class of binary stars that are luminous in X-rays. The X-rays are produced by matter falling from one component, called the ''donor'' (usually a relatively normal star), to the other component, called the ''accretor'', which ...

. In 1988 he was appointed full professor at the University of Amsterdam, and later he worked part-time at the

University of Alabama in Huntsville The University of Alabama in Huntsville (UAH) is a public research university in Huntsville, Alabama. The university is accredited by the Southern Association of Colleges and Schools and comprises nine colleges: arts, humanities & social science ...

, U.S. He published over 400 scientific papers, including many with long-time collaborator

Walter Lewin Walter Hendrik Gustav Lewin (born January 29, 1936) is a Dutch astrophysicist and retired professor of physics at the Massachusetts Institute of Technology. Lewin earned his doctorate in nuclear physics in 1965 at the Delft University of Technol ...

MIT The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

. The

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term '' ...

9259 Janvanparadijs was named after him.

References

External links

The Scientific Life and Work of Jan van Paradijs
{{DEFAULTSORT:Paradijs, Jan van 1946 births 1999 deaths Scientists from Haarlem 20th-century Dutch astronomers Academic staff of the University of Amsterdam University of Alabama in Huntsville faculty University of Amsterdam alumni Deaths from cancer in the Netherlands