Related papers: Massive Star Feedback on the IMF
The observed stellar initial mass function (IMF) appears to vary, becoming bottom-heavy in the centres of the most massive, metal-rich early-type galaxies. It is still unclear what physical processes might cause this IMF variation. In this…
Residual-gas expulsion after cluster formation has recently been shown to leave an imprint in the low-mass present-day stellar mass function (PDMF) which allowed the estimation of birth conditions of some Galactic globular clusters (GCs)…
We present an analytical method for constraining the substellar initial mass function in globular clusters, based on the observed frequency of transit events. Globular clusters typically have very high stellar densities where close…
The rapid advances in infrared detector technology over the past decades have impelled the development of wide-field instruments, and shaped our view of the cold universe. Large scale surveys in our Galaxy have discovered hundreds of brown…
We present high resolution optical spectra obtained with the HIRES spectrograph on the Keck I telescope of low mass T Tauri stars and brown dwarfs (LMTTs) in Taurus-Auriga. Of particular interest is the previously classified "continuum T…
The stellar initial mass functions (IMFs) for the Galactic bulge, the Milky Way, other galaxies, clusters of galaxies, and the integrated stars in the Universe are composites from countless individual IMFs in star clusters and associations…
We report the results of a deep near infrared (JHK) survey of the outer parts of the Trapezium Cluster with Gemini South/Flamingos. 396 sources were detected in a 26 arcmin^2 area, including 138 brown dwarf candidates, defined as M<0.075…
The stellar initial mass function (IMF) is a key property of stellar populations. There is growing evidence that the classical star-formation mechanism by the direct cloud fragmentation process has difficulties reproducing the observed…
(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 been ejected by their siblings from…
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 possible formation scenarios of massive…
It is well established that the [alpha/Fe] ratios in elliptical galaxies increase with galaxy mass. This relation holds also for early-type dwarf galaxies, although it seems to steepen at low masses. The [alpha/Fe] vs. mass relation can be…
We present the results of a recent near-infrared survey of the fields surrounding a large sample of intermediate-mass pre-main-sequence (Herbig Ae/Be) stars. While late-type Be and Ae stars are never associated with conspicuous groups of…
When calculating IMFs for young clusters, one has to take into account that (a) most massive stars are born in multiple systems (b) most IMFs are derived from data that cannot resolve such systems, and (c) multiple chance superpositions…
The highest-mass stars have the lowest frequency in the stellar IMF, and they are also the most easily observed stars. Thus, the counting statistics for OB stars provide important tests for the fundamental nature and quantitative parameters…
We review recent determinations of the present day and initial mass functions in various components of the Galaxy, disk, spheroid, young and globular clusters. As a general feature, the IMF is well described by a power-law form for $m\ga 1…
The observational consequences of the merger scenario for massive star formation are explored and contrasted with the gradual accumulation of mass by accretion. Protostellar mergers may produce high luminosity infrared flares lasting years…
Many recent works have attempted to constrain the stellar initial mass function (IMF) inside massive clusters by comparing their dynamical mass estimates to the measured light. These studies have come to different conclusions, with some…
We use the new minimum spanning tree (MST) method to look for mass segregation in the Taurus association. The method computes the ratio of MST lengths of any chosen subset of objects, including the most massive stars and brown dwarfs, to…
The observed similarities between the mass function of prestellar cores (CMF) and the stellar initial mass function (IMF) have led to the suggestion that the IMF is already largely determined in the gas phase. However, theoretical arguments…
Competitive accretion occurs when stars in a cluster accrete from a shared reservoir of gas. The competition arises due to the relative attraction of stars as a function of their mass and location in the cluster. The low relative motions of…