The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems

By Pavel Kroupa. Science, 2002

1,369 citations recorded by the source corpus.

The distribution of stellar masses that form in one star formation event in a given volume of space is called the initial mass function (IMF). The IMF has been estimated from low-mass brown dwarfs to very massive stars. Combining IMF estimates for different populations in which the stars can be observed individually unveils an extraordinary uniformity of the IMF. This general insight appears to hold for populations including present-day star formation in small molecular clouds, rich and dense massive star-clusters forming in giant clouds, through to ancient and metal-poor exotic stellar populations that may be dominated by dark matter. This apparent universality of the IMF is a challenge for star formation theory, because elementary considerations suggest that the IMF ought to systematically vary with star-forming conditions.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

• Physical Processes in the Interstellar Medium (2014, background): “More information on the stellar IMF can be found in the seminal papers by Scalo (1986), Kroupa (2002), and Chabrier (2003a), as well as in the reviews by Kroupa et al. (2013) and Offner et al. (2014).”
• The structure and dynamical evolution of the stellar disc of a simulated Milky Way-mass galaxy (2016, background): “Every star particle is treated as a single stellar population with known mass, age, and metallicity, assuming a Kroupa (2002) initial mass function (IMF) from 0.1–100M .”
• A unified multiwavelength model of galaxy formation (2015, neutral): “Comparedto the Kroupa (2002) and Chabrier (2003) IMFs that were also estimated for the solar neighbourhood, it is slightly higher around m ∼ 1 M⊙, but slightly lower form & 10 M⊙.”
• The Optical and Near-Infrared Properties of Galaxies. I. Luminosity and Stellar Mass Functions (2003, background): “These uncertainties are well-discussed in reviews by Scalo (1998) and Kroupa (2002).”
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. III. A Consistent 10 Myr Age for the Upper Scorpius OB Association (2016, background): “Neglecting magnetic inhibition of convection would produce stellar mass distributions that show a paucity of stars at higher masses compared to standard predictions for field and cluster initial mass function (e.g.,Salpeter 1955; Kroupa 2002; Chabrier 2003).”
• The Formation of Stellar Clusters in Turbulent Molecular Clouds: Effects of the Equation of State (2002, background): “Salpeter (1955) derived a power law for the high mass stellar IMF in the same notation with ν = −2.35 (see also Scalo 1998; Kroupa 2002).”
• DYNAMICAL MASS SEGREGATION ON A VERY SHORT TIMESCALE (2009, methodology): “Initial Conditions We simulate the dynamical evolution of star clusters containing 1000 single stars with masses sampled from a three-part power-law mass function (Kroupa 2002), with minimum and maximum masses of 0.08M⊙and 50M⊙, respectively.”
• Evidence for the Strong Effect of Gas Removal on the Internal Dynamics of Young Stellar Clusters (2006, background): “Studies that have done such analyses have found discrepant results, with some reporting non-standard IMFs (e.g. Smith & Gallagher 2001; Mengel et al. 2002) and others reporting standard Kroupa (2002) or Salpeter (1955) type IMFs (e.g. Maraston et al. 2004; Larsen & Richtler 2004).”
• The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function (2014, methodology): “There are num r us possible functional represent ti ns of the IMF: broken powerlaws (Kroupa 2001, 2002), lognormals to represent the peak coupled with powerlaws for the tail (Chabrier 2003, 2005), and powerlaws with exponential cutoffs at low mass (Parravano et al. 2011).”
• The First Stellar Cluster (2007, result): “The mass spectrum peaks below 1 M⊙, which is similar to the value in the solar neighborhood (Kroupa 2002; Chabrier 2003) and is also comparable to the mass of the very low metallicity subgiant stars recently discovered in the halo of our Milky Way (Christlieb et al. 2002; Beers & Christlieb 2005).”
• The formation of free-floating brown dwarves and planetary-mass objects by photo-erosion of prestellar cores (2004, background): “Similar explanations for the formation of free-floating low-mass objects have been proposed by Zapatero Osorio et al. (2000) and Kroupa (2002), but they do not appear to have been explored in detail before now.”
• The origin and evolution of the galaxy mass–metallicity relation (2015, background): “…spectra, supernovae (SNe) rates, mechanical luminosities of stellar winds, metal yields, etc., are directly tabulated from the stellar population models in STARBURST99 (Leitherer et al. 1999), assuming a Kroupa (2002) initial mass function c© 0000 RAS, MNRAS 000, 1–15 (IMF) from 0.1–100 M 2.”
• THE SPITZER c2d LEGACY RESULTS: STAR-FORMATION RATES AND EFFICIENCIES; EVOLUTION AND LIFETIMES (2008, result): “We assume a mean mass of 0.5 M⊙, consistent with studies of the IMF (Chabrier 2003, Kroupa 2002, Ninkovic & Trajkovska 2006).”
• Global collapse of molecular clouds as a formation mechanism for the most massive stars (2013, background): “Assuming now that within SDC335 (M= 5500 ± 800 M ) a fully sampled standard initial mass function forms (Kroupa 2002; Chabrier 2003), then, in addition to the early O-type star in MM1, a thousand solar mass cluster of ∼ 320 stars with masses from 1 to 50 M should emerge from SDC335.”
• THE STAR FORMATION RATE AND GAS SURFACE DENSITY RELATION IN THE MILKY WAY: IMPLICATIONS FOR EXTRAGALACTIC STUDIES (2010, result): “The mean YSO mass is consistent with IMF studies by Chabrier (2003); Kroupa (2002); Ninkovic & Trajkovska (2006).”
• The ACS survey of Galactic globular clusters. XII. Photometric binaries along the main sequence (2011, methodology): “Lower panel: Mass-ratio distribution simulated from random extraction from a Kroupa (2002) IMF in the primary star mass intervals quoted in the inset. of binaries detected by Albrow et al. (2001) in NGC 104, and Fisher et al. (1995) are not confirmed by our study.”