The influence of star clusters on galactic disks: new insights on star-formation in galaxies (2008)
Stars form in embedded star clusters which play a key role in determining the properties of a galaxy's stellar population. Physical mechanisms discussed in this paper are runaway stars shot out from...
Origin of the S Stars in the Galactic Center (2008)
Löckmann, Ulf, Baumgardt, Holger, Kroupa, Pavel
Over the last 15 years, around a hundred very young stars have been observed in the central parsec of our Galaxy. While the presence of young stars forming one or two stellar disks at approx. 0.1 pc...
The Main Sequence of Star Clusters (2008)
Kuepper, Andreas H. W., Kroupa, Pavel, Baumgardt, Holger
A novel way of looking at the evolution of star clusters is presented. With a dynamical temperature, given by the mean kinetic energy of the cluster stars, and a dynamical luminosity, which is...
Evidence for primordial mass segregation in globular clusters (2008)
Baumgardt, Holger, De Marchi, Guido, Kroupa, Pavel
We have studied the dissolution of initially mass segregated and unsegregated star clusters due to two-body relaxation in external tidal fields, using Aarseth's collisional N-body code NBODY4 on...
Dense Stellar Populations: Initial Conditions (2008)
This chapter is based on four lectures given at the Cambridge N-body school "Cambody". The material covered includes the IMF, the 6D structure of dense clusters, residual gas expulsion and the...
Marks, Michael, Kroupa, Pavel, Baumgardt, Holger
Recently de Marchi, Paresce & Pulone (2007) studied a sample of twenty globular clusters and found that all clusters with high concentrations have steep stellar mass-functions while clusters with low...
Metz, Manuel, Kroupa, Pavel, Libeskind, Noam I.
Available proper motion measurements of Milky Way (MW) satellite galaxies are used to calculate their orbital poles and projected uncertainties. These are compared to a set of recent cold dark-matter...
Most stars form in dense star clusters deeply embedded in residual gas. These objects must therefore be seen as the fundamental building blocks of galaxies. With this contribution some physical...
Mieske, Steffen, Kroupa, Pavel
A new type of compact stellar systems, labelled ``ultra-compact dwarf galaxies'' (UCDs), was discovered in the last decade. Recent studies show that their dynamical mass-to-light ratios (M/L) tend to...
Goodwin, Simon P, Nutter, Dave, Kroupa, Pavel, Ward-Thompson, Derek, Whitworth, Anthony P
Stars form from dense molecular cores, and the mass function of these cores (the CMF) is often found to be similar to the form of the stellar initial mass function (IMF). This suggests that the form...
On the origin of complex stellar populations in star clusters (2007)
Pflamm-Altenburg, Jan, Kroupa, Pavel
The existence of complex stellar populations in some star clusters challenges the understanding of star formation. E.g. the ONC or the sigma Orionis cluster host much older stars than the main bulk...
Converting Halpha luminosities into SFRs (2007)
Pflamm-Altenburg, Jan, Weidner, Carsten, Kroupa, Pavel
Star-formation rates (SFRs) of galaxies are commonly calculated by converting the measured Halpha luminosities (L_Halpha) into current SFRs. This conversion is based on a constant initial mass...
A discontinuity in the low-mass initial mass function (2007)
The origin of brown dwarfs (BDs) is still an unsolved mystery. While the standard model describes the formation of BDs and stars in a similar way recent data on the multiplicity properties of stars...
The IMF of simple and composite populations (2007)
The combination of a finite time-scale for star formation, rapid early stellar evolution and rapid stellar-dynamical processes imply that the stellar IMF cannot be inferred for any star cluster...
Baumgardt, Holger, Kroupa, Pavel
We have carried out a large set of N-body simulations studying the effect of residual-gas expulsion on the survival rate and final properties of star clusters. We have varied the star formation...
Converting H$\alpha$ Luminosities into Star Formation Rates (2007)
Pflamm-Altenburg, Jan, Weidner, Carsten, Kroupa, Pavel
The recent finding that the IGIMF (integrated galaxial initial stellar mass function) composed of all newly formed stars in all young star clusters has, in dependence of the SFR, a steeper slope in...
Maschberger, Thomas, Kroupa, Pavel
Star formation happens in a clustered way which is why the star cluster population of a particular galaxy is closely related to the star formation history of this galaxy. From the probabilistic...
The stellar initial mass function of metal-rich populations (2007)
Does the IMF vary? Is it significantly different in metal-rich environments than in metal-poor ones? Theoretical work predicts this to be the case. But in order to provide robust empirical evidence...
The initial mass function of simple and composite stellar populations (2007)
(abridged) The case can be made for a rather universal stellar IMF form that can be approximated by a two-part power-law function in the stellar regime. However, there exists a possible hint for a...
Ballero, Silvia K., Kroupa, Pavel, Matteucci, Francesca
We test whether the universal initial mass function (UIMF) or the integrated galaxial IMF (IGIMF) can be employed to explain the metallicity distribution (MD) of giants in the Galactic bulge. We make...
Pflamm-Altenburg, Jan, Kroupa, Pavel
The existence of older stars within a young star cluster can be interpreted to imply that star formation occurs on time scales longer than a free-fall time of a pre-cluster cloud core. Here the idea...
The birth and early evolution of star clusters (2006)
Star clusters are observed to form in a highly compact state and with low star-formation efficiencies, and only 10 per cent of all clusters appear to survive to middle- and old-dynamical age. If the...
The high-mass stellar IMF in different environments (2006)
The massive-star IMF is found to be invariable. However, integrated IMFs probably depend on galactic mass.
The MODEST questions: challenges and future directions in stellar cluster research (2006)
Davies, Melvyn B., Amaro-Seoane, Pau, Bassa, Cees, Dale, Jim, De Angeli, Francesca, Freitag, Marc, ...
We present a review of some of the current major challenges in stellar cluster research, including young clusters, globular clusters, and galactic nuclei. Topics considered include: primordial mass...
Fellhauer, Mike, Kroupa, Pavel, Evans, Wyn
Some of the most massive globular clusters of our Milky Way, such as for example omega-Centauri, show a mixture of stellar populations spanning a few Gyr in age and 1.5 dex in metallicities. In...
The dynamical evolution of young clusters and galactic implications (2006)
Star clusters are observed to form in a highly compact state and with low star-formation efficiencies. If the residual gas is expelled on a dynamical time the clusters disrupt thereby (i) feeding a...
The MODEST questions: challenges and future directions in stellar cluster research (2006)
Davies, Melvyn B., Amaro-Seoane, Pau, Bassa, Cees, Dale, Jim, De Angeli, Francesca, Freitag, Marc, ...
We present a review of some of the current major challenges in stellar cluster research, including young clusters, globular clusters, and galactic nuclei. Topics considered include: primordial mass...
The maximum stellar mass, star-cluster formation and composite stellar populations (2005)
Weidner, Carsten, Kroupa, Pavel
We demonstrate that the mass of the most massive star in a cluster correlates non-trivially with the cluster mass. A simple algorithm according to which a cluster is filled up with stars that are...
Induced planet formation in stellar clusters - a parameter study of star-disk encounters (2005)
Thies, Ingo, Kroupa, Pavel, Theis, Christian
We present a parameter study of the possibility of tidally triggered disk instability. Using a restricted N-body model which allows for a survey of an extended parameter space, we show that a passing...
Kroupa, Pavel, Weidner, Carsten
Theoretical considerations lead to the expectation that stars should not have masses larger than about m_{max*}=60-120Msun, while the observational evidence has been ambiguous. Only very recently has...
Limits on the primordial stellar multiplicity (2005)
Goodwin, Simon P., Kroupa, Pavel
Most stars - especially young stars - are observed to be in multiple systems. Dynamical evolution is unable to pair stars efficiently, which leads to the conclusion that star-forming cores must...
The Fundamental Building Blocks of Galaxies (2004)
Most stars form in compact, dense embedded clusters with memberships ranging from a dozen stars to many millions of stars. Embedded clusters containing more than a few hundred stars also contain O...
Kroupa, Pavel, Weidner, Carsten
(abridged) The {stellar IMF} has been found to be essentially invariant. While some apparent differences are seen, the uncertainties inherent to this game do not allow a firm conclusion to be made...
The great disk of Milky-Way satellites and cosmological sub-structures (2004)
Kroupa, Pavel, Theis, Christian, Boily, Christian M.
We show that the shape of the observed distribution of Milky Way (MW) satellites is inconsistent with being drawn from a cosmological sub-structure population with a confidence of 99.5 per cent. Most...
Monte-Carlo experiments on star-cluster induced integrated-galaxy IMF variations (2004)
Weidner, Carsten, Kroupa, Pavel
As most if not all stars are born in stellar clusters the shape of the mass function of the field stars is not only determined by the initial mass function of stars (IMF) but also by the cluster mass...
Dynamical friction in flattened systems: A numerical test of Binney's approach (2004)
Penarrubia, Jorge, Just, Andreas, Kroupa, Pavel
We carry out a set of self-consistent N-body calculations to investigate how important the velocity anisotropy in non-spherical dark-matter haloes is for dynamical friction. For this purpose we allow...
Evidence for a fundamental stellar upper mass limit from clustered star formation (2003)
Weidner, Carsten, Kroupa, Pavel
The observed masses of the most massive stars do not surpass about 150Msun. This may either be a fundamental upper mass limit which is defined by the physics of massive stars and/or their formation,...
On the origin of brown dwarfs and free-floating planetary mass objects (2003)
Kroupa, Pavel, Bouvier, Jerome
(abridged) Sub-stellar mass objects have fundamentally different binary properties than stars implying that they cannot have the same formation history. They are rather unfinished stars having either...
Massive Stars: Their Birth Sites and Distribution (2003)
The stellar IMF has been found to be an invariant Salpeter power-law (alpha=2.35) above about 1 Msun, but at the same time a massive star typically has more than one companion. This constrains the...
Galactic-Field IMFs of Massive Stars (2003)
Kroupa, Pavel, Weidner, Carsten
Over the past years observations of young and populous star clusters have shown that the stellar IMF appears to be an invariant featureless Salpeter power-law with an exponent alpha=2.35 for stars...
The dynamical evolution of Taurus--Auriga-type aggregates (2003)
Kroupa, Pavel, Bouvier, Jerome
(abridged) Star formation in the Taurus--Auriga (TA) molecular clouds is producing binary-rich aggregates containing at most a few dozen systems within a region spanning one pc without massive stars....
Sills, Alison, Deiters, Stefan, Eggleton, Peter P., Freitag, Marc, Giersz, Mirek, Heggie, Douglas C., ...
This is a summary paper of MODEST-2, a workshop held at the Astronomical Institute ‘Anton Pannekoek’ in Amsterdam, 16-17 December 2002. MODEST is a loose collaboration of people...
Sills, Alison, Deiters, Stefan, Eggleton, Peter P., Freitag, Marc, Giersz, Mirek, Heggie, Douglas C., ...
This is a summary paper of MODEST-2, a workshop held at the Astronomical Institute ‘Anton Pannekoek’ in Amsterdam, 16-17 December 2002. MODEST is a loose collaboration of people...
Sills, Alison, Deiters, Stefan, Eggleton, Peter P., Freitag, Marc, Giersz, Mirek, Heggie, Douglas C., ...
This is a summary paper of MODEST-2, a workshop held at the Astronomical Institute ‘Anton Pannekoek’ in Amsterdam, 16-17 December 2002. MODEST is a loose collaboration of people...
Sills, Alison, Deiters, Stefan, Eggleton, Peter P., Freitag, Marc, Giersz, Mirek, Heggie, Douglas C., ...
This is a summary paper of MODEST-2, a workshop held at the Astronomical Institute ‘Anton Pannekoek’ in Amsterdam, 16-17 December 2002. MODEST is a loose collaboration of people...
On the mass function of star clusters (2002)
Kroupa, Pavel, Boily, Christian
Clusters that form in total 10^3 < N < 10^5 stars (type II clusters) lose their gas within a dynamical time as a result of the photo-ionising flux from O stars. Sparser (type I) clusters get rid of...
Satellite decay in flattened dark matter haloes (2002)
Penarrubia, Jorge, Kroupa, Pavel, Boily, Christian M.
We carry out a set of self-consistent N-body calculations to compare the decay rates of satellite dwarf galaxies orbiting a disc galaxy embedded in a dark matter halo (DMH). We consider both...
The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems (2002)
The distribution of stellar masses that form in one star-formation event in a given volume of space is called the initial mass function (IMF). The IMF has been estimated from low-mass brown dwarfs to...
Binary systems, star clusters and the galactic field population : applied stellar dynamics / (2002)
Kiel, University, Diss., 2002.
Thickening of galactic disks through clustered star formation (2001)
(Abridged) The building blocks of galaxies are star clusters. These form with low-star formation efficiencies and, consequently, loose a large part of their stars that expand outwards once the...
On the origin of the distribution of binary-star periods (2001)
Kroupa, Pavel, Burkert, Andreas
Pre-main sequence and main-sequence binary systems are observed to have periods, P, ranging from one day to 10^(10) days and eccentricities, e, ranging from 0 to 1. We pose the problem if...
The mean surface density of companions in a stellar-dynamical context (2001)
Applying the mean surface density of companions, Sigma(r), to the dynamical evolution of star clusters is an interesting approach to quantifying structural changes in a cluster. It has the advantage...
The Initial Mass Function and its Variation (2001)
The observed distribution of IMF shapes can be understood as statistical sampling from a universal IMF and variations that result from stellar-dynamical processes. However, young star clusters appear...
Impact of Gas Removal on the Evolution of Embedded Clusters (2001)
Boily, Christian, Kroupa, Pavel
We study both analytically and numerically the disruptive effect of instantaneous gas removal from an embedded cluster. We setup a calculation based on the stellar velocity distribution function, to...
The formation of a bound star cluster : from the Orion nebula cluster to the Pleiades (2001)
Kroupa, Pavel, Aarseth, Sverre J., Hurley, Jarrod R.
Direct N-body calculations are presented of the formation of Galactic clusters using GASEX, which is a variant of the code Nbody6. The calculations focus on the possible evolution of the Orion nebula...
The formation of a bound star cluster : from the Orion nebula cluster to the Pleiades (2001)
Kroupa, Pavel, Aarseth, Sverre J., Hurley, Jarrod R.
Direct N-body calculations are presented of the formation of Galactic clusters using GASEX, which is a variant of the code Nbody6. The calculations focus on the possible evolution of the Orion nebula...
The formation of a bound star cluster : from the Orion nebula cluster to the Pleiades (2001)
Kroupa, Pavel, Aarseth, Sverre J., Hurley, Jarrod R.
Direct N-body calculations are presented of the formation of Galactic clusters using GASEX, which is a variant of the code Nbody6. The calculations focus on the possible evolution of the Orion nebula...
The formation of a bound star cluster : from the Orion nebula cluster to the Pleiades (2001)
Kroupa, Pavel, Aarseth, Sverre J., Hurley, Jarrod R.
Direct N-body calculations are presented of the formation of Galactic clusters using GASEX, which is a variant of the code Nbody6. The calculations focus on the possible evolution of the Orion nebula...
The Local Stellar Initial Mass Function (2000)
This contribution describes the difficult task of inferring the IMF from local star-count data, by discussing the mass-luminosity relation, unresolved binary, triple and quadruple systems, abundance...
The Birth, Evolution and Death of Star Clusters (2000)
A dense-enough gas-accumulation evolves, over a few Myr of intensifying star formation, to an embedded cluster. If it contains a sufficient amount of mass, O stars form and explosively expel the...
Binary Stars in Young Clusters - a Theoretical Perspective (2000)
The preponderance of binary systems in all known stellar populations makes them exciting dynamical agents for research on topics as varied as star formation, star-cluster dynamics and the interiors...
On the variation of the Initial Mass Function (2000)
(shortened) In this contribution an average or Galactic-field IMF is defined, stressing that there is evidence for a change in the power-law index at only two masses: near 0.5 Msun and 0.08 Msun....
Could merged star-clusters build up a small galaxy? (2000)
Fellhauer, Michael, Kroupa, Pavel
We investigate the behaviour of a cluster of young massive star clusters (hereafter super-cluster) in the tidal field of a host galaxy with a high-resolution particle-mesh code, Superbox....
Stellar-Dynamics of Young Star Clusters (2000)
The stellar-dynamical evolution of bound star clusters during the first few Myr is dominated by binary-binary and binary-star interactions, the rapid sinking of the most massive stars to the centre...
Constraints on Stellar-Dynamical Models of the Orion Nebula Cluster (1999)
The results obtained by Kroupa, Petr & McCaughrean (1999) for specific models of young compact binary-rich clusters are generalised using dynamical scaling relations, to infer the candidate set of...
Binary stars in young clusters: models versus observations of the Trapezium Cluster (1999)
Kroupa, Pavel, Petr, Monika, McCaughrean, Mark
The frequency of low-mass pre-main sequence binary systems is significantly lower in the Trapezium Cluster than in Taurus-Auriga. We investigate if this difference can be explained through stellar...
An Expanding Trapezium Cluster? (1998)
Simulations with Aarseth's (1994) NBODY5 code are presented of an initially dense binary-rich cluster. It is assumed that the star formation efficiency is 50 per cent with instantaneous mass loss....
The dynamical evolution of stellar super-clusters (1998)
Recent images taken with the Hubble Space Telescope (HST) of the interacting disk galaxies NGC 4038/4039 (the Antennae) reveal clusters of many dozens and possibly hundreds of young compact massive...
Pavel Kroupa, Christopher A. Tout
. We investigate the dependence of theoretically generated mass--(absolute magnitude) relations on stellar models. Using up-to-date physics we compute models of stars in the mass range 0:1 ! m 1 m fi...
. We postulate that stars in the Galactic field are born in aggregates of binary stars with half mass radii R 0:5 and number of binaries N bin which are dynamically equivalent to the dominant mode...
Are The Nearby And Photometric Stellar Luminosity Functions Different? (1998)
The stellar luminosity function derived from the sample of stars within 5.2--20 pc is the nearby luminosity function. The luminosity function obtained from deep low spatial resolution surveys to...
dSph Satellite Galaxies without Dark Matter: a Study of Parameter Space (1998)
A parameter study is underway in Heidelberg that aims to find and constrain possible solutions to the dSph satellite problem under the assumption that some of these systems may not be dark matter...
On the Binary Properties and the Spatial and Kinematical Distribution of Young Stars (1998)
The effects which star cluster concentration and binarity have on observable parameters, that characterise the dynamical state of a population of stars after their birth aggregate dissolves, are...
Dynamical Interactions in Dense Stellar Clusters (1998)
This chapter reviews the dynamical processes in young stellar clusters. The accretion of gas by individual stars affects the dynamics of the cluster, and the masses of the stars. Dynamical mass...
Formation of dSph Satellites without Dark Matter (1998)
Recently it was shown that low-mass galaxies containing no dark matter can naturally evolve to dSph-like satellites in a tidal field. Such dSph-like satellites fake total domination by dark matter....
Self-consistent simulations of the dynamical evolution of a low-mass satellite galaxy without dark matter are reported. The orbits have eccentricities 0.46 0.5. Some remnants have sub-structure...
The Stellar Mass Function (1997)
Since the major review by Scalo (1986), significant progress has been achieved in constraining the mass function (MF) of low-mass stars. The break-throughs which today allow a much better...
The Theoretical Mass--Magnitude Relation of Low-Mass Stars and its Metallicity Dependence (1997)
Kroupa, Pavel, Tout, Christopher A.
We investigate the dependence of theoretically generated mass - (absolute magnitude) relations on stellar models. Using up to date physics we compute models in the mass range 0.1 < m < 1M_sun. We...
Dwarf Spheroidal Satellite Galaxies and the Galactic Tidal Field (1996)
The Milky Way is surrounded by nine or more dwarf-spheroidal (dSph) satellite galaxies that appear to consist primarily of dark matter. Here I summarise research that shows that initially spherical...
Inverse Dynamical Population Synthesis and Star Formation (1995)
We investigate the hypothesis that stars form in aggregates of binary systems and that the dynamical evolution of these aggregates leads to the observed properties of binary stars in the Galactic...
The Dynamical Properties of Stellar Systems in the Galactic Disc (1995)
We postulate that most stars are born in aggregates of binary systems which are dynamically equivalent to the `dominant mode cluster'. The initial binary orbits are consitent with pre-main sequence...
We use N-body integration to follow the evolution of clusters of 200 binary systems with different initial half mass radii $R_{0.5}$. We also simulate single-star clusters. All clusters evolve...
UNIFICATION OF THE NEARBY AND PHOTOMETRIC STELLAR LUMINOSITY FUNCTIONS (1995)
We introduce a model Galactic field low-mass stellar population that has a proportion of binary systems as observed, with a mass ratio distribution consistent with observational constraints. The...
ARE THE NEARBY AND PHOTOMETRIC STELLAR LUMINOSITY FUNCTIONS DIFFERENT? (1995)
The stellar luminosity function derived from the sample of stars within 5.2--20~pc is the nearby luminosity function. The luminosity function obtained from deep low spatial resolution surveys to...
The distribution of low-mass stars in the disc of the galaxy. (1992)
Thesis (Ph. D.)--University of Cambridge, 1992.