The stellar initial mass function (IMF) integrated over an entire galaxy is an integral over all separate star-formation events. Since most stars form in star clusters with different masses the integrated IMF becomes an integral of the (universal or invariant) canonical stellar IMF over the star-cluster mass function. This integrated IMF is steeper (contains fewer massive stars per Gtype star) ...

Understanding the formation of stars in galaxies is central to much of modern astrophysics. However, a quantitative prediction of the star formation rate and the initial distribution of stellar masses remains elusive. For several decades it has been thought that the star formation process is primarily controlled by the interplay between gravity and magnetostatic support, modulated by neutral-io...

We have derived the star formation history of the Milky Way disk over the last 2 Gyr with a time resolution of 0.05 Gyr from the age distribution diagram of a large sample of open clusters comprising more than 580 objects. By interpreting the age distribution diagram using numerical results from an extensive library of N-body calculations carried out during the last ten years, we reconstruct th...

Context. Despite many studies of the star formation in spiral galaxies, a complete and coherent understanding of the physical processes that regulate the birth of stars has not yet been achieved, nor a unanimous consent was reached, despite the many attempts, on the effects of the environment on the star formation in galaxies member of rich clusters. Aims. We focus on the local and global Schmi...

We report subarcsecond images of the high-mass star forming region Onsala 1 (ON 1) made with the Submillimeter Array (SMA) at 0.85 mm and the Very Large Array at 1.3 cm and 3.6 cm. ON 1 is one of the smallest ultracompact H II regions in the Galaxy and exhibits various star formation signposts. With our VLA and SMA observations, two new cm-wave sources and five sub-mm dust sources, respectively...

Context. Star formation remains an unsolved problem in astrophysics. Numerical studies of large-scale structure simulations cannot resolve the process and their approach usually assumes that only gas denser than a typical threshold can host and form stars. Aims. We investigate the onset of cosmological star formation and compare several very-high-resolution, three-dimensional, Nbody/SPH simulat...

Understanding the physical processes that drive star formation is a key challenge for galaxy formation models. In this paper, we study the tight correlation between the star formation rate (SFR) and stellar mass of galaxies at a given redshift, how halo growth influences star formation, and star formation histories of individual galaxies. We study these topics using Illustris, a state-of-the-ar...

Surveys of redshifted emission lines in the near-infrared will provide unique information on the cosmic star formation history. Near-infrared Hα surveys will probe the cosmic star formation density and the evolution of the luminosity function of star forming galaxies out to z ∼ 2.5, including the important z = 1.5 − 2.0 epoch, where according to current knowledge the cosmic star formation densi...

The manner in which gas accretes and orbits within circumnuclear rings has direct implications for the star formation process. In particular, gas may be compressed and shocked at the inflow points, resulting in bursts of star formation at these locations. Afterwards the gas and young stars move together through the ring. In addition, star formation may occur throughout the ring, if and when the...

A chromospheric age distribution of 552 latetype dwarfs is transformed into a star formation history by the application of scale height corrections, stellar evolutionary corrections and volume corrections. We show that the disk of our Galaxy has experienced enhanced episodes of star formation at 0-1 Gyr, 2-5 Gyr and 7-9 Gyr ago, although the reality of the latter burst is still uncertain. The s...