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The universality of the stellar initial mass function (IMF) is tested using Bayesian statistics with a sample of eight young Galactic stellar clusters (IC 348, ONC, NGC 2024, NGC 6611, NGC 2264, $\rho$ Ophiuchi, Chameleon I, and Taurus). We…

Astrophysics of Galaxies · Physics 2015-06-19 Sami Dib

Crucial for star formation is the interplay between gravity and turbulence. The observed cloud virial parameter, $\alpha_{\mathrm{vir}}$, which is the ratio of twice the turbulent kinetic energy to the gravitational energy, is found to vary…

Astrophysics of Galaxies · Physics 2025-01-07 Sajay Sunny Mathew , Christoph Federrath , Amit Seta

Stars form from dense molecular cores, and the mass function of these cores (the CMF) is often found to be similar to the form of the stellar initial mass function (IMF). This suggests that the form of the IMF is the result of the form of…

It has frequently been suggested that the stellar IMF in galaxies was top-heavy at early times. This would be plausible physically if the IMF depends on a mass scale such as the Jeans mass that was higher at earlier times because of the…

Astrophysics · Physics 2009-10-30 Richard B. Larson

The stellar initial mass function (IMF) describes the distribution of stellar masses that form in a given star formation event. The long main-sequence lifetimes of low-mass stars mean that the IMF in this regime (below $\sim 1…

The stellar initial mass function (IMF) is central to our interpretation of astronomical observables and to our understanding of most baryonic processes within galaxies. The universality of the IMF, suggested by observations in our own…

One of the key mysteries of star formation is the origin of the stellar initial mass function (IMF). The IMF is observed to be nearly universal in the Milky Way and its satellites, and significant variations are only inferred in extreme…

Cosmological simulations are reaching the resolution necessary to study ultra-faint dwarf galaxies. Observations indicate that in small populations, the stellar initial mass function (IMF) is not fully populated; rather, stars are sampled…

Astrophysics of Galaxies · Physics 2020-02-24 Elaad Applebaum , Alyson M. Brooks , Thomas R. Quinn , Charlotte R. Christensen

Recent estimates point to abundances of z > 4 sub-millimeter (sub-mm) galaxies far above model predictions. The matter is still debated. According to some analyses the excess may be substantially lower than initially thought and perhaps…

Astrophysics of Galaxies · Physics 2020-03-06 Zhen-Yi Cai , Gianfranco De Zotti , Matteo Bonato

We review computational approaches to understanding the origin of the Initial Mass Function (IMF) during the formation of star clusters. We examine the role of turbulence, gravity and accretion, equations of state, and magnetic fields in…

Solar and Stellar Astrophysics · Physics 2015-05-20 Ralph E. Pudritz

The Interstellar Medium (ISM) is a complex, multi-phase system, where the history of the stars occurs. The processes of birth and death of stars are strongly coupled to the dynamics of the ISM. The observed chaotic and diffusive motions of…

Astrophysics of Galaxies · Physics 2011-02-02 D. Falceta-Goncalves

We present models for the initial mass function (IMF) for stars forming within molecular clouds. These models use the idea that stars determine their own masses through the action of powerful stellar outflows. This concept allows us to…

Astrophysics · Physics 2009-10-28 Fred C. Adams , Marco Fatuzzo

The stellar initial mass function (IMF) is an essential input for many astrophysical studies but only in a few cases it has been determined over the whole cluster mass range, limiting the conclusions about its nature. The 25 Orionis group…

The dependence of the stellar initial mass function (IMF) on star-formation environment, particularly at low metallicities and high redshifts, remains poorly constrained. Ultra-faint dwarf galaxies (UFDs) are local fossils of high-redshift…

Evidence from different probes of the stellar initial mass function (IMF) of massive early-type galaxies (ETGs) has repeatedly converged on IMFs more bottom-heavy than in the Milky Way (MW). This consensus has come under scrutiny due to…

Astrophysics of Galaxies · Physics 2023-09-29 Kianusch Mehrgan , Jens Thomas , Roberto Saglia , Taniya Parikh , Bianca Neureiter , Peter Erwin , Ralf Bender

In this review, we examine the successes and weaknesses of modern low-mass star and brown dwarf theory.(1) We first focus on the mechanical (equation of state) and thermal (atmosphere) properties and on the evolution. We then examine the…

Astrophysics · Physics 2016-08-30 G. Chabrier , I. Baraffe , F. Allard , P. H. Hauschildt

As star-forming clouds collapse, the gas within them fragments to ever-smaller masses. Naively one might expect this process to continue down to the smallest mass that is able to radiate away its binding energy on a dynamical timescale, the…

Astrophysics of Galaxies · Physics 2016-07-27 Mark R. Krumholz , Andrew T. Myers , Richard I. Klein , Christopher F. McKee

In the solar neighborhood, the Initial Mass Function (IMF) follows is canonically described by the Salpeter power-law slope for the high-mass range. The stellar IMF may directly result from a Core Mass Function (CMF) through accretion,…

Astrophysics of Galaxies · Physics 2026-05-06 B. Thomasson , I. Joncour , E. Moraux , F. Motte , T. Yoo , A. Ginsburg

MHD Turbulence is a critical component of the current paradigms of star formation, particle transport, magnetic reconnection and evolution of the ISM. Progress on this difficult subject is made via numerical simulations and observational…

Astrophysics of Galaxies · Physics 2011-05-06 Blakesley Burkhart , Alex Lazarian

Gamma rays of ~TeV energies from distant sources suffer attenuation due to pair production off of ~1 micron EBL photons. We may exploit this process in order to indirectly measure the EBL and constrain models of galaxy formation. Here,…

Astrophysics · Physics 2010-12-09 J. S. Bullock , R. S. Somerville , D. MacMinn , J. R. Primack