Star Cluster Formation and Disruption Time-Scales - II. Evolution of the Star Cluster System in M82's Fossil Starburst

For decades, the nuclear starburst has taken all the limelight in M82 with very little discussion on M82 as a galaxy. The situation is changing over the last decade, with the publication of some important results on the morphology and stellar content of its disk and halo. In this review, we discuss these recent findings in the framework of M82 as a galaxy. It is known for almost half a century that M82 as a galaxy doesn't follow the trends expected for normal galaxies that ha...

Spectroscopic, photometric and dynamical data of the inner 3 kpc part of the starburst galaxy M82 are analyzed in order to investigate the star formation history of the stellar disk. The long-slit spectra along the major axis are dominated by Balmer absorption lines in the region outside the nuclear starburst all the way up to ~3.5 scalelengths (mu_B=22 mag/arcsec**2). Single Stellar Population (SSP) spectra of age 0.4-1.0 Gyr match well the observed spectra in the 1-3 kpc zo...

We observed the nearby starburst galaxy M82 in CO in the higher frequency (2--1) transition to achieve an angular resolution below 1 arc second or 17 pc at the target. We resolved the molecular gas into a large number of compact clouds, with masses ranging from about 2x10^3 to 2x10^6 solar masses. The mass spectrum scales as N(M) ~ M^-1.5, similar to the mass spectra of young massive star clusters suggesting that individual molecular clouds are transformed in the starburst in...

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 them unbound. A cluster disruption model has recently been proposed in which this mass- independent disruption of clusters proceeds for another Gyr after gas expulsion. In this scenario, the survival chances of massive clusters are much small...

(Abridged) The dynamical ejection of stars from star clusters affects the shape of the stellar mass function (MF) in these clusters, because the escape probability of a star depends on its mass. The objective of this paper is to provide and to apply a simple physical model for the evolution of the MF in star clusters for a large range of the parameter space. The model is derived from the basic principles of two-body encounters and energy considerations. It is independent of t...

In previous papers of this series, we developed a new algorithm for modeling the formation of star clusters in galaxy formation simulations. Here we investigate how dissolution of bound star clusters affects the shape of the cluster mass function and the metallicity distribution of surviving clusters. Cluster evolution includes the loss of stars that become unbound due to tidal disruption as well as mass-loss due to stellar evolution. We calculate the tidal tensor along clust...

M82 is the nearest starburst galaxy. It contains two large systems of super star clusters, one being spawned today in the active starforming core, and one produced by an earlier starburst event which coincided with the last orbital passage of its neighbor, M81. The proximity of M82 makes it uniquely valuable for a wide range of studies of massive young clusters and their environments.

Star clusters are often used as tracers of major star formation events in external galaxies as they can be studied up to much larger distances than individual stars. It is vital to understand their evolution if they are used to derive, for example, the star formation history of their host galaxy. More specifically, we want to know how cluster lifetimes depend on their environment and structural properties such as mass and radius. This review presents a theoretical overview of...

An overview of our current understanding of the formation and evolution of star clusters is given, with main emphasis on high-mass clusters. Clusters form deeply embedded within dense clouds of molecular gas. Left-over gas is cleared within a few million years and, depending on the efficiency of star formation, the clusters may disperse almost immediately or remain gravitationally bound. Current evidence suggests that a few percent of star formation occurs in clusters that re...

We present a detailed study of two luminous super star clusters in the starburst galaxy M82. Spectra, covering 3250-8790 A at a resolution of 1.6 A, were obtained at the 4.2 m William Herschel Telescope (WHT) for cluster F and the highly reddened cluster L. We compare the strengths of the observed Balmer absorption lines and the Balmer jump in the blue spectrum of F with theoretical model cluster spectra using the PEGASE spectral synthesis code to derive an age of 60+/-20 Myr...