Pavel Kroupa
Encyclopedia
Pavel Kroupa is an Australia
n astrophysicist and professor at the University of Bonn
.
, Kroupa's family fled from Czechoslovakia loosing all posessions; as a consequence Kroupa grew up in Germany and South Africa. He acquired in 1983 his Abitur
final exams in Göttingen
and afterwards studied physics at The University of Western Australia in Perth
. In 1988 he won the Isaac Newton scholarship at the University of Cambridge
and in 1992 the senior Rouse Ball
research scholarship at Trinity College, Cambridge
and attained a doctorate in England in 1992 with a dissertation on the distribution of low mass stars in the Milky Way
. Afterwards Kroupa worked until 2000 in astronomical research groups at Heidelberg University and at the Max Planck Institute for Astronomy, before he went to the University of Kiel
and earned his Habilitation
there. He was awarded a Heisenberg Fellowship in 2002. In April 2004 he was appointed to the observatory of the University of Bonn, which is today a department of the Argelander Institute for Astronomy. He was honored in 2007 by a Swinburne University Visiting Professorship in Melbourne and by a Leverhulme Trust Visiting Professorship at the Univiersity of Sheffield.
Pavel Kroupa is married and has a son.
Kroupa leads the research group on stellar populations and stellar dynamics at the University of Bonn. His research work began in 1987 in Australia with an investigation of Proxima Centauri
. Kroupa is well known for his work for the distribution of stellar masses. In Cambridge in 1990-1992 by means of observational data on star counts and on binary stars and with detailed computations of stellar structure with Christopher A. Tout and Gerard Gilmore he deduced the contemporary, generally-used canonical IMF (initial mass function
), which describes the distribution of the star masses at their birth. In 2004 in Kiel together with Carsten Weidner he suggested the existence of a physical maximum star mass of approximately 150 solar masses. In Heidelberg he presented the first stellar-dynamic computations in 1993-1995 of star clusters, in which all stars are born as binary stars. He thus solved the problem that field populations have a significantly lower double star rate than star formation areas, because the binary stars are broken up as the star clusters evolve and disperse. He mathematically formulated and applied a theory of the evolution of binary stars (eigenevolution), created the method of dynamic population synthesis, and predicted the existence of binary stars forbidden by previous theory (forbidden binaries). He suggested in cooperation with Ingo Thies and Christian Theis in 2003-2004 in Kiel that brown dwarves and extrasolar planetary systems can develop in circumstellar disks due to passing stars which disturb the disks. Our Solar System is likely to have been shaped by such events.
In Kiel he also theoretically formulated the concept that galaxies ought to be described by stars forming in populations of embedded star clusters. With this he explained in 2002 the observed heating or thickening with age of the disk of the Milky Way, and with Carsten Weidner he formulated the "IGIMF (integrated galactic initial mass function) theory". In 2008 in Bonn together with Jan Pflamm-Altenburg he pointed out that the IGIMF theory implies that disk galaxies have a radial star formation law, in which the star formation density is proportional to the radial gas density. The IGIMF theory implies also that the star formation rates of irregular dwarf galaxies are proportional to their gas masses and must be corrected to clearly higher values as compared to previous theory. Simple star-formation laws for galaxies emerge from this work. The IGIMF theory gives good predictions for the mass distributions of the various metals within galaxies.
In 1997 and in Heidelberg Kroupa, together with Ulrich Bastian, took the first precise measurement of the spatial movement of two extragalactic systems. In 1997 he also discovered stellar-dynamic solutions for the satellite galaxies of the Milky Way without the need for exotic dark matter. His work implies a possible connection of the satellite galaxies with the Bulge of the Milky Way. This connection can be explained by a collision of the early Milky Way with another young galaxy during which the satellite galaxies formed as tidal dwarf galaxies about 11 Gyr ago. This is shown in a series of research papers with Manuel Metz and Marcel Pawlowski.
As a result of this work and since 2010 Kroupa has concerned himself increasingly with cosmology. While the cosmological standard model
does not offer a unique solution to the cosmic background radiation and to cosmological expansion, he finds that the observed structures on scales of 10 Mpc and less falsify the standard model. The implication of his work is that effective gravity must be non-Newtonian in the ultra-weak field limit.
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n astrophysicist and professor at the University of Bonn
University of Bonn
The University of Bonn is a public research university located in Bonn, Germany. Founded in its present form in 1818, as the linear successor of earlier academic institutions, the University of Bonn is today one of the leading universities in Germany. The University of Bonn offers a large number...
.
Biography and career
After the 1968 failure of Prague springPrague Spring
The Prague Spring was a period of political liberalization in Czechoslovakia during the era of its domination by the Soviet Union after World War II...
, Kroupa's family fled from Czechoslovakia loosing all posessions; as a consequence Kroupa grew up in Germany and South Africa. He acquired in 1983 his Abitur
Abitur
Abitur is a designation used in Germany, Finland and Estonia for final exams that pupils take at the end of their secondary education, usually after 12 or 13 years of schooling, see also for Germany Abitur after twelve years.The Zeugnis der Allgemeinen Hochschulreife, often referred to as...
final exams in Göttingen
Göttingen
Göttingen is a university town in Lower Saxony, Germany. It is the capital of the district of Göttingen. The Leine river runs through the town. In 2006 the population was 129,686.-General information:...
and afterwards studied physics at The University of Western Australia in Perth
Perth, Western Australia
Perth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....
. In 1988 he won the Isaac Newton scholarship at the University of Cambridge
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
and in 1992 the senior Rouse Ball
W. W. Rouse Ball
-External links:*...
research scholarship at Trinity College, Cambridge
Trinity College, Cambridge
Trinity College is a constituent college of the University of Cambridge. Trinity has more members than any other college in Cambridge or Oxford, with around 700 undergraduates, 430 graduates, and over 170 Fellows...
and attained a doctorate in England in 1992 with a dissertation on the distribution of low mass stars in the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
. Afterwards Kroupa worked until 2000 in astronomical research groups at Heidelberg University and at the Max Planck Institute for Astronomy, before he went to the University of Kiel
University of Kiel
The University of Kiel is a university in the city of Kiel, Germany. It was founded in 1665 as the Academia Holsatorum Chiloniensis by Christian Albert, Duke of Holstein-Gottorp and has approximately 23,000 students today...
and earned his Habilitation
Habilitation
Habilitation is the highest academic qualification a scholar can achieve by his or her own pursuit in several European and Asian countries. Earned after obtaining a research doctorate, such as a PhD, habilitation requires the candidate to write a professorial thesis based on independent...
there. He was awarded a Heisenberg Fellowship in 2002. In April 2004 he was appointed to the observatory of the University of Bonn, which is today a department of the Argelander Institute for Astronomy. He was honored in 2007 by a Swinburne University Visiting Professorship in Melbourne and by a Leverhulme Trust Visiting Professorship at the Univiersity of Sheffield.
Pavel Kroupa is married and has a son.
Kroupa leads the research group on stellar populations and stellar dynamics at the University of Bonn. His research work began in 1987 in Australia with an investigation of Proxima Centauri
Proxima Centauri
Proxima Centauri is a red dwarf star about 4.2 light-years distant in the constellation of Centaurus. It was discovered in 1915 by Robert Innes, the Director of the Union Observatory in South Africa, and is the nearest known star to the Sun, although it is too faint to be seen with the naked eye...
. Kroupa is well known for his work for the distribution of stellar masses. In Cambridge in 1990-1992 by means of observational data on star counts and on binary stars and with detailed computations of stellar structure with Christopher A. Tout and Gerard Gilmore he deduced the contemporary, generally-used canonical IMF (initial mass function
Initial mass function
The initial mass function is an empirical function that describes the mass distribution of a population of stars in terms of their theoretical initial mass...
), which describes the distribution of the star masses at their birth. In 2004 in Kiel together with Carsten Weidner he suggested the existence of a physical maximum star mass of approximately 150 solar masses. In Heidelberg he presented the first stellar-dynamic computations in 1993-1995 of star clusters, in which all stars are born as binary stars. He thus solved the problem that field populations have a significantly lower double star rate than star formation areas, because the binary stars are broken up as the star clusters evolve and disperse. He mathematically formulated and applied a theory of the evolution of binary stars (eigenevolution), created the method of dynamic population synthesis, and predicted the existence of binary stars forbidden by previous theory (forbidden binaries). He suggested in cooperation with Ingo Thies and Christian Theis in 2003-2004 in Kiel that brown dwarves and extrasolar planetary systems can develop in circumstellar disks due to passing stars which disturb the disks. Our Solar System is likely to have been shaped by such events.
In Kiel he also theoretically formulated the concept that galaxies ought to be described by stars forming in populations of embedded star clusters. With this he explained in 2002 the observed heating or thickening with age of the disk of the Milky Way, and with Carsten Weidner he formulated the "IGIMF (integrated galactic initial mass function) theory". In 2008 in Bonn together with Jan Pflamm-Altenburg he pointed out that the IGIMF theory implies that disk galaxies have a radial star formation law, in which the star formation density is proportional to the radial gas density. The IGIMF theory implies also that the star formation rates of irregular dwarf galaxies are proportional to their gas masses and must be corrected to clearly higher values as compared to previous theory. Simple star-formation laws for galaxies emerge from this work. The IGIMF theory gives good predictions for the mass distributions of the various metals within galaxies.
In 1997 and in Heidelberg Kroupa, together with Ulrich Bastian, took the first precise measurement of the spatial movement of two extragalactic systems. In 1997 he also discovered stellar-dynamic solutions for the satellite galaxies of the Milky Way without the need for exotic dark matter. His work implies a possible connection of the satellite galaxies with the Bulge of the Milky Way. This connection can be explained by a collision of the early Milky Way with another young galaxy during which the satellite galaxies formed as tidal dwarf galaxies about 11 Gyr ago. This is shown in a series of research papers with Manuel Metz and Marcel Pawlowski.
As a result of this work and since 2010 Kroupa has concerned himself increasingly with cosmology. While the cosmological standard model
Lambda-CDM model
ΛCDM or Lambda-CDM is an abbreviation for Lambda-Cold Dark Matter, which is also known as the cold dark matter model with dark energy...
does not offer a unique solution to the cosmic background radiation and to cosmological expansion, he finds that the observed structures on scales of 10 Mpc and less falsify the standard model. The implication of his work is that effective gravity must be non-Newtonian in the ultra-weak field limit.
Works
- The distribution of low-mass stars in the disc of the galaxy. University of Cambridge, 1992 (PhD thesis)
- Binary systems, star clusters and the galactic-field population: applied stellar dynamics. Kiel, 2002 (Habilitation thesis)
- The initial mass function of stars: evidence for uniformity in variable systems. Volume 295, Issue 5552 of Science Weekly, American Association for the Advancement of Science, 2002
Journal articles
- P. Kroupa, R.R. Burman, D.G. Blair, "Photometric observations of flares on Proxima Centauri",PASA 8, 119 (1989).
- P. Kroupa, C. A. Tout, G. Gilmore, "The distribution of low-mass stars in the Galactic disc",MNRAS 262, 545 (1993).
- P. Kroupa, "The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems",Science 295, 82 (2002).
- C. Weidner, P. Kroupa, "Evidence for a fundamental stellar upper mass limit from clustered star formation",MNRAS 348, 187 (2004).
- P. Kroupa, "Inverse dynamical population synthesis and star formation", MNRAS 277, 1491 (1995).
- P. Kroupa, "The dynamical properties of stellar systems in the Galactic disc", MNRAS 277, 1507 (1995).
- I. Thies, P. Kroupa, C. Theis, "Induced planet formation in stellar clusters: a parameter study of star-disc encounters", MNRAS 364, 961 (2005).
- I. Thies, P. Kroupa, S.P. Goodwin et al., "Tidally Induced Brown Dwarf and Planet Formation in Circumstellar Disks", ApJ 717, 577 (2010).
- P. Kroupa, "Thickening of galactic discs through clustered star formation", MNRAS 330, 707 (2002).
- C. Weidner, P. Kroupa, "The Variation of Integrated Star Initial Mass Functions among Galaxies",ApJ 625, 754 (2005).
- J. Pflamm-Altenburg, P.Kroupa, "Clustered star formation as a natural explanation for the Hα cut-off in disk galaxies", Nature 455, 641 (2008).
- J. Pflamm-Altenburg, P.Kroupa, "The Fundamental Gas Depletion and Stellar-Mass Buildup Times of Star-Forming Galaxies", ApJ 706, 516 (2009).
- J. Köppen, C. Weidner, P. Kroupa, "A possible origin of the mass-metallicity relation of galaxies", MNRAS 375, 673 (2007).
- S. Recchi, F. Calura, P. Kroupa, "The chemical evolution of galaxies within the IGIMF theory: the [ α/Fe] ratios and downsizing", A&A 499, 711 (2009).
- P. Kroupa, U. Bastian, "The HIPPARCOS proper motion of the Magellanic Clouds", NewA 2, 77 (1997).
- P. Kroupa, "Dwarf spheroidal satellite galaxies without dark matter", NewA 2,139 (1997).
- P. Kroupa, B. Famaey, K.S. de Boer, J. Dabringhausen, M. Pawlowski, C.M. Boily, H. Jerjen, D. Forbes, G. Hensler, M. Metz, "Local-Group tests of dark-matter concordance cosmology . Towards a new paradigm for structure formation", A&A 523, 32 (2010).