Michiel Baldur Maximiliaan van der Klis (born 9 June 1953) is a Dutch astronomer best known for his work on extreme 'pairings' of stars called

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 ...

, more particularly his explanation of the occurrence of

quasi-periodic oscillations In X-ray astronomy, quasi-periodic oscillation (QPO) is the manner in which the X-ray light from an astronomical object flickers about certain frequencies. In these situations, the X-rays are emitted near the inner edge of an accretion disk in w ...

(QPOs) in these systems and his co-discovery of the first millisecond X-ray

pulsar A pulsar (from ''pulsating radio source'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Ea ...

. In the 1980s he gained worldwide fame with his investigation of QPOs. His revolutionary discoveries have had an enormous impact in his field of research; in effect, they have made it what it is today. Van der Klis pioneered special mathematical analysis techniques that are now regarded as the “gold standard” within his discipline.

Research

Van der Klis's research focuses on

, pairs of stars orbiting each other that emit

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

radiation. Some

binary star system A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

s contain a compact object like 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. white ...

or a

black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...

. By studying the dynamics of materials in the vicinity of such objects one can learn about their

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

and

rotational speed Rotational frequency (also known as rotational speed or rate of rotation) of an object Rotation around a fixed axis, rotating around an axis is the frequency of rotation of the object. Its unit is revolution per minute (rpm), cycle per second ...

. Moreover, this kind of research provides a testing ground for

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 ...

and

general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...

. Van der Klis made a number of breakthrough discoveries. In 1984 he discovered the first type of QPOs (quasi-periodic oscillations of the X-ray emission) of compact stars while he was working with ESA's EXOSAT satellite to study the strongest X-ray sources near the centre of the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

. One of his achievements is the explanation in 1985 why

s emitted from binary systems do not come in steady pulses (like the radiowaves emitted by pulsars), but in short irregular bursts. His studies in the years 1984-1987 clarified the principles for classifying the several hundreds of strong X-ray sources known to exist in our

Galaxy A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

. In the 1990s, he and his research group, including

Rudy Wijnands Rudy Wijnands (born 1971) is a Dutch astrophysicist. He is professor of Observational High-Energy Astrophysics at the University of Amsterdam. Academic career Since 2004 Wijnands has been part of the faculty with the Anton Pannekoek Institute ...

, discovered the first millisecond X-ray pulsar in a binary system, SAX J1808.4-3658, a neutron star spinning around its axis more than 400 times per second. The discovery of this superfast spinning neutron star attracted great international attention.

Academic career

Van der Klis obtained his PhD at University of Amsterdam in 1983 working on observations of X-ray binaries. For a while he worked at the

ESA , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (1205 ...

lab

ESTEC The European Space Research and Technology Centre (ESTEC) is the European Space Agency's main technology development and test centre for spacecraft and space technology. It is situated in Noordwijk, South Holland, in the western Netherlands, altho ...

in Noordwijk. In 1989 he returned to the University of Amsterdam as an associate professor and was made full professor of

Astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

in 1993. Since 2002 he is an elected member of the

Royal Netherlands Academy of Arts and Sciences The Royal Netherlands Academy of Arts and Sciences ( nl, Koninklijke Nederlandse Akademie van Wetenschappen, abbreviated: KNAW) is an organization dedicated to the advancement of science and literature in the Netherlands. The academy is housed ...

(KNAW) and since 2003 also of the

Koninklijke Hollandsche Maatschappij der Wetenschappen The Koninklijke Hollandsche Maatschappij der Wetenschappen (Royal Holland Society of Sciences and Humanities), located on the east side of the Spaarne in downtown Haarlem, Netherlands, was established in 1752 and is the oldest society for the sci ...

(KHMW). Since 2005 he is Director of the Astronomical Institute Anton Pannekoek of 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 being ...

and Chair of the Netherlands Research School for Astronomy (NOVA).

Honors and awards

Van der Klis received a number of awards for his pioneering research, including the

Bruno Rossi Prize The Bruno Rossi Prize is awarded annually by the High Energy Astrophysics division of the American Astronomical Society "for a significant contribution to High Energy Astrophysics, with particular emphasis on recent, original work". Named after as ...

(1987), the most important international distinction awarded in high-energy

astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...

, and the

Spinoza Prize The Spinoza Prize ( nl, Spinozapremie) is an annual award of 2.5 million euro, to be spent on new research given by the Dutch Research Council (NWO). The award is the highest scientific award in the Netherlands. It is named after the philosopher ...

(2004). On April 27, 2010, the

(KNAW) awarded an Academy Professorship to him. The international review committee noted: "He is a world leader in the X-ray radiation of compact objects and has formulated an intriguing connection between black holes and neutron stars, the two most extreme objects in the universe. He and his research group also discovered the first X-ray pulsar with a rotation speed of four hundred revolutions per second." He was elected a Legacy Fellow of the

American Astronomical Society The American Astronomical Society (AAS, sometimes spoken as "double-A-S") is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the adv ...

in 2020.

Awards

*1987

*1990

COSPAR The Committee on Space Research (COSPAR) was established on October 3, 1958 by the International Council for Scientific Unions (ICSU). Among COSPAR's objectives are the promotion of scientific research in space on an international level, wi ...

Zel'dovich Medal *1991 NWO Pionier grant *1998 Visiting

Miller A miller is a person who operates a Gristmill, mill, a machine to grind a grain (for example corn or wheat) to make flour. Mill (grinding), Milling is among the oldest of human occupations. "Miller", "Milne" and other variants are common surname ...

Professorship Award, University of California Berkeley *2004

*2010

KNAW The Royal Netherlands Academy of Arts and Sciences ( nl, Koninklijke Nederlandse Akademie van Wetenschappen, abbreviated: KNAW) is an organization dedicated to the advancement of science and literature in the Netherlands. The academy is housed ...

Academy Professorship

References

* Jury report for his 2004 Spinozapremie. * * Jury report for his 2010 KNAW nomination.

External links

Link to all papers by Michiel van der Klis on the ArXivLink to the NARCIS scientific portal
{{DEFAULTSORT:Klis, Michiel Van Der 1953 births Living people 20th-century Dutch astronomers University of Amsterdam alumni Academic staff of the University of Amsterdam Members of the Royal Netherlands Academy of Arts and Sciences Scientists from The Hague Spinoza Prize winners Fellows of the American Astronomical Society 21st-century Dutch astronomers