Alexander Godfried Gerardus Maria (Xander) Tielens (born 1953) is an astronomer at

Leiden Observatory Leiden Observatory ( nl, Sterrewacht Leiden) is an astronomical institute of Leiden University, in the Netherlands. Established in 1633 to house the quadrant of Rudolph Snellius, it is the oldest operating university observatory in the world, with ...

Leiden University Leiden University (abbreviated as ''LEI''; nl, Universiteit Leiden) is a Public university, public research university in Leiden, Netherlands. The university was founded as a Protestant university in 1575 by William the Silent, William, Prince o ...

, in the Netherlands. In 2012 he received the highest distinction in Dutch science, 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 ...

Biography

Tielens has contributed significantly to several fields of astronomy, including interstellar physics and astrochemistry. He is mostly known for his work on large aromatic molecules (

PAHs A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. ...

) in space and on

photodissociation region In astrophysics, photodissociation regions (or photon-dominated regions, PDRs) are predominantly neutral regions of the interstellar medium in which far ultraviolet photons strongly influence the gas chemistry and act as the most important sourc ...

s. He is also the author of a reference textbook on the

interstellar medium In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstella ...

. Tielens is the project scientist of the HIFI instrument on board of the

Herschel Space Observatory The Herschel Space Observatory was a space observatory built and operated by the European Space Agency (ESA). It was active from 2009 to 2013, and was the largest infrared telescope ever launched until the launch of the James Webb Space Telesc ...

. He used to be the

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

Project Scientist of the

Stratospheric Observatory for Infrared Astronomy The Stratospheric Observatory for Infrared Astronomy (SOFIA) was an 80/20 joint project of NASA and the German Aerospace Center (DLR) to construct and maintain an airborne observatory. NASA awarded the contract for the development of the aircraf ...

. Since 2012 Tielens has been a 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 ...

References

1953 births Living people 20th-century Dutch astronomers Leiden University alumni Academic staff of Leiden University Members of the Royal Netherlands Academy of Arts and Sciences Spinoza Prize winners Academic staff of the University of Groningen 21st-century Dutch astronomers {{Astronomer-stub