New professor hunts planets and listens to the stars

Hans Kjeldsen has been appointed Professor of Observational Asteroseismology and Exoplanet Studies at the Department of Physics and Astronomy, Aarhus University. The aim of his research is to understand the stars, their interiors, their surroundings and activity, and their planetary systems.

2013.12.16 | Rasmus Rørbæk Christensen

Hans Kjeldsen has been appointed professor at the Department of Physics and Astronomy, Aarhus University. (Photo: Lars Kruse, AU Communication)

In the interior of stars, there are sound waves that create changes in the brightness of the stars on the surface. In a way, it could be said that asteroseismologists listen to the tones emitted by the stars and convert the ‘ring’ of the tones to knowledge about physical conditions in the interior. Asteroseismology is the technique used to study the sound waves on their way through the stars. Researchers can use this to develop theories about the structure and development of stars and planets. This is Professor Kjeldsen’s field of research at Aarhus University.

“We’re in the midst of a golden age for observations of the universe. It’s only in the last decade that we’ve had such fantastic opportunities for studying the properties of stars and discovering, observing and collecting data about foreign solar systems. In recent years, the Kepler spacecraft has provided us with unique information about stars and planetary systems. We now know that the universe contains countless planets the size of the Earth, and we’ve created fundamental new insight into the life cycle of the stars,” says Professor Kjeldsen.

Knowledge should be shared
Teaching has always been a large part of Professor Kjeldsen’s daily life, and he regards teaching and communicating as one of his greatest tasks at all levels of the degree programme in Astronomy. In 2010, he was awarded the Aarhus University Anniversary Foundation’s Pedagogical Prize of Honour for his teaching skills.

It is not only university students who benefit from his communication skills, however. Professor Kjeldsen gives about fifty lectures a year for different associations, state schools, upper secondary schools, folk high schools, teacher’s training colleges, planetariums, and the Danish University Extension in Aarhus. Together with a colleague, he co-authored the book De dynamiske stjerner (The Dynamic Stars) for physics classes, and they are currently finishing off new teaching material about exoplanets.

In 1989, Hans Kjeldsen (born 1963) graduated with an MSc in Astronomy from Aarhus University, where he subsequently completed his PhD. He carried out part of his PhD project at the Nordic Optical Telescope on the island of La Palma. From 1992 to 1993, he worked at the European Southern Observatory (ESO) in Germany, and has been employed at Aarhus University since 1994, first as a postdoctoral fellow and assistant professor, prior to an appointment as associate professor in 2004.

In addition to his research and teaching, Professor Kjeldsen is Manager of the Stellar Astrophysics Centre (SAC), a basic research centre that opened in 2012 and is headed by Professor Jørgen Christensen-Dalsgaard.

Professor Kjeldsen also sits on a number of boards and committees, where he is chair of the Nordic Optical Telescope’s Technical Scientific Committee, member of the Board of the Nordic Optical Telescope, deputy chair of the European Southern Observatory’s User Committee, member of the Professional Forum for Physics, and member of the Board of the Odder Upper Secondary School.

During his career, Professor Kjeldsen’s research has been financed by bodies including the Danish National Research Foundation, the European Union, the Danish Council for Independent Research | Natural Sciences (FNU) , the Carlsberg Foundation, the Villum Foundation, and via international collaborations.

Read more about some of the discoveries Professor Kjeldsen has been associated with:

Life in space: so close – and yet so far away (in Danish only)

Disorderly planetary system challenges the theories

The smallest planet in the universe – to date – has been found!

Kepler. A satellite for the history books (in Danish only)

For more information, please contact

Professor Hans Kjeldsen

Science and Technology, Staff