scholarly journals The Initial Mass Function in Young Star Clusters

1986 ◽  
Vol 7 ◽  
pp. 489-499
Author(s):  
Hans Zinnecker
Keyword(s):  
Star Formation ◽  
Recent Work ◽  
Star Clusters ◽  
Mass Function ◽  
Young Star ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Stellar Content ◽  
Young Star Clusters ◽  
The Imf

AbstractThis review discusses both the earlier and the most recent work on the IMF in young star clusters. It is argued that the study of the stellar content of young star clusters offers the best chance of developing a theory of star formation and of the IMF.

scholarly journals Young Star Clusters in the LMC

1992 ◽  
Vol 45 (4) ◽  
pp. 407
Author(s):  
KC Freeman
Keyword(s):  
Mass Loss ◽  
Globular Clusters ◽  
Star Clusters ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Young Star ◽  
Stellar Mass ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Young Star Clusters

The young globular star clusters in the LMC offer us insights into the formation and early dynamical evolution of globular clusters which are unobtainable from the old globular clusters in our Galaxy. Because these young clusters are so young and populous, they provide an opportunity to measure the upper end of the initial mass function by direct means and also through the dynamical effects of stellar mass loss on the structure of the clusters.

scholarly journals The influence of star clusters on galactic disks: new insights in star-formation in galaxies

2008 ◽  
Vol 4 (S254) ◽  
pp. 209-220
Author(s):  
Pavel Kroupa
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Stellar Population ◽  
Dwarf Galaxy ◽  
Star Clusters ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Disk Galaxies ◽  
Galactic Disks

AbstractStars form in embedded star clusters which play a key role in determining the properties of a galaxy's stellar population. A large fraction of newly born massive stars are shot out from dynamically unstable embedded-cluster cores spreading them to large distances before they explode. Embedded clusters blow out their gas once the feedback energy from the new stellar population overcomes its binding energy, leading to cluster expansion and in many cases dissolution into the galaxy. Galactic disks may be thickened by such processes, and some thick disks may be the result of an early epoch of vigorous star-formation. Binary stellar systems are disrupted in clusters leading to a lower fraction of binaries in the field, while long-lived clusters harden degenerate-stellar binaries such that the SNIa rate may increase by orders of magnitude in those galaxies that were able to form long-lived clusters. The stellar initial mass function of the whole galaxy must be computed by adding the IMFs in the individual clusters. The resulting integrated galactic initial mass function (IGIMF) is top-light for SFRs < 10 M⊙/yr, and its slope and, more importantly, its upper stellar mass limit depend on the star-formation rate (SFR), explaining naturally the mass–metallicity relation of galaxies. Based on the IGIMF theory, the re-calibrated Hα-luminosity–SFR relation implies dwarf irregular galaxies to have the same gas-depletion time-scale as major disk galaxies, implying a major change of our concept of dwarf-galaxy evolution. A galaxy transforms about 0.3 per cent of its neutral gas mass every 10 Myr into stars. The IGIMF-theory also naturally leads to the observed radial Hα cutoff in disk galaxies without a radial star-formation cutoff. It emerges that the thorough understanding of the physics and distribution of star clusters may be leading to a major paradigm shift in our understanding of galaxy evolution.

scholarly journals The Initial Mass Function of Be Stars

2004 ◽  
Vol 215 ◽  
pp. 83-84
Author(s):  
J. Zorec ◽  
R. Levenhagen ◽  
J. Chauville ◽  
Y. Frémat ◽  
D. Ballereau ◽  
...  
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Be Stars ◽  
Fast Rotation ◽  
Formation Conditions ◽  
The Imf

Allowing for systematic differences in the counting of Be Stars due to their overluminosity, changes produced by their fast rotation on spectral types and time spent in the main sequence, a difference between the IMF (Be) and IMF(B) appears, which indicates that the appearance of the Be phenomenon may relay on differences in the initial star formation conditions.

scholarly journals Star Formation in Cooling Flows

1987 ◽  
Vol 127 ◽  
pp. 167-177
Author(s):  
R. W. O'Connell
Keyword(s):  
Star Formation ◽  
Stellar Populations ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Flow Forming ◽  
Cooling Flows ◽  
Cd Galaxies ◽  
Ngc 1275 ◽  
The Imf

Star formation, probably with an abnormal initial mass function, represents the most plausible sink for the large amounts of material being accreted by cD galaxies from cooling flows. There are three prominent cases (NGC 1275, PKS 0745-191, and Abell 1795) where cooling flows have apparently induced unusual stellar populations. Recent studies show that about 50% of other accreting cD's have significant ultraviolet excesses. It therefore appears that detectable accretion populations are frequently associated with cooling flows. The questions of the form of the IMF, the fraction of the flow forming stars, and the lifetime of the flow remain open.

scholarly journals The Mass Function of Young Star Clusters in our Galaxy and Nearby Galaxies: Is It Universal?

2002 ◽  
Vol 207 ◽  
pp. 515-524
Author(s):  
Ram Sagar
Keyword(s):  
Star Clusters ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Young Star ◽  
Initial Mass Function ◽  
Galactocentric Distance ◽  
Photometric Observations ◽  
Nearby Galaxies ◽  
Mass Segregation ◽  
Young Star Clusters

Mass functions (MFs) derived from photometric observations of young star clusters of our Galaxy, the Magellanic Clouds (MCs), M31 and M33 have been used to investigate the question of universality of the initial mass function and presence of mass segregation in these systems. Observational determination of the MF slope of young star clusters have an inherent uncertainty of at least ∼ 1.0 dex in the Milky Way and of ∼ 0.4 dex in the MCs. There is no obvious dependence of the MF slope on either galactocentric distance or age of the young star clusters or on the spatial concentration of the stars formed or on the galactic characteristics including metallicity. Effects of mass segregation have been observed in a good number of young stellar groups of our Galaxy and MCs. As their ages are much smaller than their dynamical evolution times, star formation processes seem to be responsible for the observed mass segregation in them.

scholarly journals Dynamical Masses of Young Star Clusters: Constraints on the Stellar IMF and Star-Formation Efficiency

2007 ◽  
Vol 3 (S246) ◽  
pp. 32-35
Author(s):  
N. Bastian
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Young Star ◽  
Initial Mass Function ◽  
Gas Removal ◽  
Stellar Initial Mass Function ◽  
Rapid Removal ◽  
Young Clusters ◽  
Formation Efficiency ◽  
Young Star Clusters

AbstractThrough the use of detailed light profiles and dynamical measurements of young clusters we investigate claims that the stellar initial mass function within clusters varies greatly. We find a strong age dependence in the clusters which have been claimed to have non-standard stellar IMFs, and suggest that the lack of equilibrium of these clusters is responsible for their ‘strange’ light-to-mass ratios and not IMF variations. The most likely culprit is the rapid removal of residual gas left over from the star-formation process which leaves the clusters severely out of dynamical equilibrium. By comparing the observations to N-body simulations we quantify to what degree a cluster is out of equilibrium and consequently its survival chances. We find that >60% of young clusters will be disrupted, due gas removal, within the first 20–50 Myr of their lives.

scholarly journals Population synthesis from clustered star formation

2009 ◽  
Vol 5 (S262) ◽  
pp. 347-348
Author(s):  
M. R. Haas ◽  
P. Anders
Keyword(s):  
Power Law ◽  
Star Clusters ◽  
Mass Function ◽  
Initial Mass Function ◽  
High Mass ◽  
Initial Mass ◽  
Stellar Content ◽  
Exact Shape ◽  
Stellar Masses ◽  
Power Law Index

In recent years, a series of papers (Kroupa & Weidner 2003, Weidner & Kroupa 2004, Weidner & Kroupa 2005 and Weidner & Kroupa 2006, WK06 from now on) have proposed that the stellar content of an entire galaxy may not be well described by the same initial mass function (IMF) that describes the distribution of stellar masses in the star clusters, where these stars form. The reason is that star clusters also form with a cluster mass function (CMF), which is a power law with a power law index of ~−2. If the lowest mass clusters are of masses smaller than the physical upper mass limit for stars they will be deficient in high mass stars. Therefore, if the stellar content of all clusters is added together, making up the Integrated Galactic Initial Mass Function (IGIMF), the distribution of stellar masses may be steeper at the high mass end, depending on the exact shape of the CMF.

scholarly journals What does the IMF really tell us about star formation?

2009 ◽  
Vol 5 (S262) ◽  
pp. 368-369
Author(s):  
M. B. N. Kouwenhoven ◽  
S. P. Goodwin
Keyword(s):  
Star Formation ◽  
Formation Process ◽  
Stellar Population ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Detailed Knowledge ◽  
Mass Ratio ◽  
Ratio Distribution ◽  
The Imf

AbstractObtaining accurate measurements of the initial mass function (IMF) is often considered to be the key to understanding star formation, and a universal IMF is often assumed to imply a universal star formation process. Here, we illustrate that different modes of star formation can result in the same IMF, and that, in order to truly understand star formation, a deeper understanding of the primordial binary population is necessary. Detailed knowledge on the binary fraction, mass ratio distribution, and other binary parameters, as a function of mass, is a requirement for recovering the star formation process from stellar population measurements.

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