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The stellar Initial Mass Function (IMF) seems to be close to universal in the local star-forming regions. However, this quantity of a newborn stellar population responds differently at gas metallicities $Z \sim$ $Z_\odot$ than $Z$ = 0. A…

Astrophysics of Galaxies · Physics 2021-03-31 Rafeel Riaz , Dominik R. G. Schleicher , Siegfried Vanaverbeke , Ralf S. Klessen

I use a sample of more than 120,000 stars in the solar neighbourhood with parallaxes, magnitudes and colours estimated with unprecedented accuracy by the second data release of the Gaia mission to derive the initial mass function of the…

Astrophysics of Galaxies · Physics 2019-09-25 A. Sollima

The birth of stars and the formation of galaxies are cornerstones of modern astrophysics. While much is known about how galaxies globally and their stars individually form and evolve, one fundamental property that affects both remains…

Astrophysics of Galaxies · Physics 2019-02-20 A. M. Hopkins

I present infrared spectroscopy of 37 brown dwarf candidates in the Upper Sco association, 35 of which are classified as young and cool, making them likely members. This sample includes many of the faintest spectroscopically confirmed…

Solar and Stellar Astrophysics · Physics 2025-05-29 K. L. Luhman

Here we present a full description of the integrated galaxy-wide initial mass function (IGIMF) theory in terms of the optimal sampling and compare it with available observations. Optimal sampling is the method we use to discretize the IMF…

Astrophysics of Galaxies · Physics 2017-11-29 Z. Yan , T. Jerabkova , P. Kroupa

The stellar initial mass function (IMF) is a fundamental astrophysical quantity that impacts a wide range of astrophysical problems from heavy element distribution to galactic evolution to planetary system formation. However, the origin and…

Solar and Stellar Astrophysics · Physics 2017-01-11 S. S. R. Offner

We analyse multi-wavelength observations of 32 young star clusters and associations in M33 with known oxygen abundance (8 < 12 + log(O/H) < 8.7), using ultraviolet (UV), optical, mid-infrared (MIR), CO (1-0) and 21-cm line (HI)…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 M. Grossi , E. Corbelli , C. Giovanardi , L. Magrini

We investigated a volume-limited sample of LAMOST main-sequence stars with masses from 0.25 to 1 $M_{\odot}$ and distances of 150-350 pc to explore how the stellar initial mass function (IMF) varies with metallicity. We corrected the…

Solar and Stellar Astrophysics · Physics 2025-11-07 Dan Qiu , Chao Liu , Jennifer A. Johnson , Jiadong Li , Bo Zhang

We use deep Hubble Space Telescope photometry of the rich, young (~20-45 Myr-old) star cluster NGC 1818 in the Large Magellanic Cloud to derive its stellar mass function (MF) down to ~0.15 Msun. This represents the deepest robust MF thus…

Solar and Stellar Astrophysics · Physics 2015-05-13 Q. Liu , R. de Grijs , L. C. Deng , Y. Hu , I. Baraffe , S. F. Beaulieu

We use N-body simulations to model the 12 Gyr evolution of a suite of star clusters with identical initial stellar mass functions over a range of initial cluster masses, sizes, and orbits. Our models reproduce the distribution of…

Astrophysics of Galaxies · Physics 2015-09-23 Jeremy J. Webb , Nathan W. C. Leigh

Several observational and theoretical indications suggest that the initial mass function (IMF) becomes increasingly top-heavy (i.e., overabundant in high-mass stars with mass $m > 1M_{\odot}$) with decreasing metallicity and increasing gas…

Astrophysics of Galaxies · Physics 2020-12-15 Hosein Haghi , Ghasem Safaei , Akram Hasani Zonoozi , Pavel Kroupa

The abundance of brown dwarfs (BDs) in young clusters is a diagnostic of star formation theory. Here we revisit the issue of determining the substellar initial mass function (IMF), based on a comparison between NGC1333 and IC348, two…

Solar and Stellar Astrophysics · Physics 2015-06-17 Aleks Scholz , Vincent Geers , Paul Clark , Ray Jayawardhana , Koraljka Muzic

We derive a semi-empirical galactic initial mass function (IMF) from observational constraints. We assume that the star formation rate in a galaxy can be expressed as the product of the IMF, $\psi (m)$, which is a smooth function of mass…

Astrophysics of Galaxies · Physics 2015-05-20 Antonio Parravano , Christopher F. McKee , David J. Hollenbach

We present new measurements of the velocity dispersions of eleven Local Group globular clusters using spatially integrated spectra, to expand our sample of clusters with precise integrated-light velocity dispersions to 29, over 4 different…

Astrophysics of Galaxies · Physics 2015-06-22 Dennis Zaritsky , Janet E. Colucci , Peter M. Pessev , Rebecca A. Bernstein , Rupali Chandar

We show the results of deep V and I HST photometry of 6 rich star clusters in the Large Magellanic Cloud with different ages and metallicities. The number of stars with measured magnitudes in each cluster varies from about 3000 to 10000. We…

Astrophysics · Physics 2009-11-06 B. Santiago , S. Beaulieu , R. Johnson , G. Gilmore

An essential component of galaxy formation theory is the stellar initial mass function (IMF), that describes the parent distribution of stellar mass in star forming regions. We present observational evidence in a sample of early-type…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 I. Ferreras , F. La Barbera , R. R. de Carvalho , I. G. de la Rosa , A. Vazdekis , J. Falcon-Barroso , E. Ricciardelli

A robust stellar initial mass function (IMF) is crucial in any studies related to star formation. However, the direct measurement of the stellar IMF is confined to the local universe, limited by the resolving power of telescopes. Recently,…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-12 Sung Kei Li

We determine an absolute calibration of the initial mass function (IMF) of early-type galaxies, by studying a sample of 56 gravitational lenses identified by the SLACS Survey. Under the assumption of standard Navarro, Frenk & White dark…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 T. Treu , M. W. Auger , L. V. E. Koopmans , R. Gavazzi , P. J. Marshall , A. S. Bolton

The stellar initial mass function (IMF) is commonly assumed to be an invariant probability density distribution function of initial stellar masses being represented by the canonical IMF. As a consequence the galaxy-wide IMF (gwIMF), defined…

Astrophysics of Galaxies · Physics 2018-11-28 T. Jerabkova , A. H. Zonoozi , P. Kroupa , G. Beccari , Z. Yan , A. Vazdekis , Z. -Y. Zhang