Related papers: Open cluster stability and the effects of binary s…
Binary systems, in particular eclipsing binaries, are essential sources of our knowledge of the fundamental properties of stars. The ages of binaries, members of open clusters, are constrained by their own fundamental properties and by…
The formation of globular clusters remains an open debate. Dwarf starburst galaxies are efficient at forming young massive clusters with similar masses as globular clusters and may hold the key to understanding their formation. We study…
Spectral line indices for a sample of 290 nearby E and S0 galaxies are used to investigate the stellar populations of these galaxies. Relations are established between the line indices (Mg2, <Fe>, Hbeta) and the velocity dispersions, the…
There is much debate on how high-mass star formation varies with environment, and whether the sparsest star-forming environments are capable of forming massive stars. To address this issue, we have observed eight apparently isolated OB…
We analyse multi-wavelength observations of 32 young star clusters and associations in M33 with known oxygen abundance (8 < 12 + log(O/H) < 8.7), using ultraviolet (UV), optical, mid-infrared (MIR), CO (1-0) and 21-cm line (HI)…
The formation of massive stellar clusters is intricately linked to star formation on local and global scales. All actively star forming galaxies are forming clusters, and the local initial conditions likely determine whether bound massive…
The degree of mass loss, i.e. the fraction of stars lost by globular clusters, and specifically by their different populations, is still poorly understood. Many scenarios of the formation of multiple stellar populations, especially the ones…
From a study of the integrated light properties of 200 globular clusters (GCs) in M31, Strader et al. found that the mass-to-light ratios are lower than what is expected from simple stellar population (SSP) models with a `canonical' stellar…
The distribution of stars and stellar remnants (white dwarfs, neutron stars, black holes) within globular clusters holds clues about their formation and long-term evolution, with important implications for their initial mass function (IMF)…
The distribution of core radii of rich clusters in the Large Magellanic Cloud (LMC) systematically increases in both upper limit and spread with increasing cluster age. Cluster-to-cluster variations in the stellar initial mass function…
Open clusters, which have age, abundance, and extinction information from studies of main-sequence turn off stars, are the ideal location in which to determine the mass-luminosity-radius relation for low-mass stars. We have undertaken a…
The numerous and massive young star clusters in blue compact galaxies (BCGs) are used to investigate the properties of their hosts. We test whether BCGs follow claimed relations between cluster populations and their hosts, such as the the…
The stellar initial mass function (IMF) determines the relative number of stars born at a given mass. Despite the tremendous effort to establish a universal IMF, the astronomical literature offers a wealth of diverse evidence for IMF…
Few topics in astronomy initiate such vigorous discussion as whether or not the initial mass function (IMF) of stars is universal, or instead sensitive to the initial conditions of star formation. The distinction is of critical importance:…
We provide a review of the current status of several topics on the ages, distances, and mass functions of open clusters, with a particular emphasis on illuminating the areas of uncertainty. Hipparcos has obtained parallaxes for nearby open…
Most stars do not form in isolation but as part of a cluster comprising anywhere between a few dozen to several million stars with stellar densities ranging from 0.01 to several 10$^5$ \Msun pc$^{-3}$. The majority of these clusters…
Aims: Based on our well-determined sample of open clusters in the all-sky catalogue ASCC-2.5 we derive new linear sizes of some 600 clusters, and investigate the effect of mass segregation of stars in open clusters. Methods: Using…
Many embedded star clusters do not evolve into long-lived bound clusters. The most popular explanation for this "infant mortality" of young clusters is the expulsion of natal gas by stellar winds and supernovae, which leaves up to 90% of…
Context: Field stars are not always single stars, but can often be found in bound double systems. Since binary frequencies in the birth places of stars, young embedded clusters, are sometimes even higher than on average the question arises…
There is growing evidence that star clusters can no longer be considered simple stellar populations (SSPs). Intermediate and old age clusters are often found to have extended main sequence turn-offs (eMSTOs) which are difficult to explain…