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Related papers: The stellar initial mass function of nearby young …

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Recent work has suggested that the stellar initial mass function (IMF) is not universal, but rather is correlated with galaxy stellar mass, stellar velocity dispersion, or morphological type. In this paper, we investigate variations of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 A. A. Dutton , T. Treu , B. J. Brewer , P. J. Marshall , M. W. Auger , M. Barnabe , D. C. Koo , A. S. Bolton , L. V. E. Koopmans

We present an investigation about the shape of the initial mass function (IMF) of early-type galaxies (ETGs), based on a joint lensing and dynamical analysis, and on stellar population synthesis models, for a sample of 55 lens ETGs…

Astrophysics of Galaxies · Physics 2015-06-22 Silvia Posacki , Michele Cappellari , Tommaso Treu , Silvia Pellegrini , Luca Ciotti

In the last decade, growing evidence has emerged supporting a non-universal stellar Initial Mass Function (IMF) in massive galaxies, with a larger number of dwarf stars with respect to the Milky-Way (bottom-heavy IMF). However, a consensus…

We present a new measurement of the stellar initial mass function (IMF) based on ultra-deep, high-resolution photometry of >5,000 stars in the outskirts of the Small Magellanic Cloud (SMC) galaxy. The Hubble Space Telescope (HST) Advanced…

We present the results of numerical experiments designed to evaluate the usefulness of near-infrared luminosity functions for constraining the Initial Mass Function (IMF) of young stellar populations. From this numerical modeling, we find…

Astrophysics · Physics 2009-10-31 August A. Muench , Elizabeth A. Lada , Charles J. Lada

When a detailed model of a stellar population is unavailable, it is most common to assume that stellar masses are independently and identically distributed according to some distribution: the universal initial mass function (IMF). However,…

The stellar initial mas function (IMF) has been described as being invariant, bottom heavy or top-heavy in extremely dense star burst conditions. To provide usable observable diagnostic we calculate redshift dependent spectral energy…

Astrophysics of Galaxies · Physics 2018-01-04 Tereza Jerabkova , Pavel Kroupa , Joerg Dabringhausen , Michael Hilker , Kenji Bekki

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…

Astrophysics · Physics 2008-11-26 Gilles Chabrier

Star formation in the early Universe has left its imprint on the chemistry of observable stars in galaxies. We derive elemental abundances and the slope of the low-mass end of the initial mass function (IMF) for a sample of 25 very massive…

Astrophysics of Galaxies · Physics 2024-04-08 Mark den Brok , Davor Krajnović , Eric Emsellem , Wilfried Mercier , Matthias Steinmetz , Peter M. Weilbacher

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

We use the timescale distribution of ~3000 microlensing events measured by the OGLE-III survey, together with accurate new made-to-measure dynamical models of the Galactic bulge/bar region, to measure the IMF in the inner Milky Way. The…

Astrophysics of Galaxies · Physics 2017-07-26 Christopher Wegg , Ortwin Gerhard , Matthieu Portail

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 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 confirm 66 low-mass stellar and brown dwarf systems (K7-M9) plus 19 visual or spectroscopic companions of the beta Pictoris Moving Group (BPMG). Of these, 41 are new discoveries, increasing the known low-mass members by 45%. We also add…

Solar and Stellar Astrophysics · Physics 2017-08-02 Evgenya L. Shkolnik , Katelyn N. Allers , Adam L. Kraus , Michael C. Liu , Laura Flagg

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

The turnover in the stellar initial mass function (IMF) at low mass suggests the presence of two independent mass functions that combine in different ways above and below a characteristic mass given by the thermal Jeans mass in the cloud.…

Astrophysics · Physics 2009-10-31 Bruce Elmegreen

Using new long-slit spectroscopy obtained with X-Shooter at ESO-VLT, we study, for the first time, radial gradients of optical and Near-Infrared IMF-sensitive features in a representative sample of galaxies at the very high-mass end of the…

Some theories of star formation suggest massive stars may only form in clustered environments, which would create a deficit of massive stars in low density environments. Observationally, Massey (2002) finds such a deficit in samples of the…

Astrophysics of Galaxies · Physics 2015-06-12 J. B. Lamb , M. S. Oey , A. S. Graus , F. C. Adams , D. M. Segura-Cox

We present new observations of the three nearest early-type galaxy (ETG) strong lenses discovered in the SINFONI Nearby Elliptical Lens Locator Survey (SNELLS). Based on their lensing masses, these ETGs were inferred to have a stellar…

Astrophysics of Galaxies · Physics 2017-08-30 Andrew B. Newman , Russell J. Smith , Charlie Conroy , Alexa Villaume , Pieter van Dokkum

The stellar initial mass function (IMF), which is often assumed to be universal across unresolved stellar populations, has recently been suggested to be "bottom-heavy" for massive ellipticals. In these galaxies, the prevalence of…