TY - JOUR
T1 - Stellar mass spectrum within massive collapsing clumps
T2 - II. Thermodynamics and tidal forces of the first Larson core. A robust mechanism for the peak of the IMF
AU - Lee, Yueh Ning
AU - Hennebelle, Patrick
N1 - Funding Information:
Acknolw edgements. We thank the anonymous referee for comments that have improved the manuscript. We thank Gilles Chabrier for a critical reading of the manuscript. We thank Michel Rieutord for providing the ESTER code and helping us to run it to explore the influence of the rotation on the mass of a polytrope. This work was granted access to HPC resources of CINES under the allocation x2014047023 made by GENCI (Grand Equipement National de Calcul Intensif). This research has received funding from the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013 Grant Agreement no. 306483). Y.-N. Lee acknowledges the financial support of the UnivEarthS Labex program at Sorbonne Paris Cité (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02).
Publisher Copyright:
© ESO 2018.
PY - 2018/3/1
Y1 - 2018/3/1
N2 - Context. Understanding the origin of the initial mass function (IMF) of stars is a major problem for the star formation process and beyond.Aim. We investigate the dependence of the peak of the IMF on the physics of the so-called first Larson core, which corresponds to the point where the dust becomes opaque to its own radiation.Methods. We performed numerical simulations of collapsing clouds of 1000 M for various gas equations of state (eos), paying great attention to the numerical resolution and convergence. The initial conditions of these numerical experiments are varied in the companion paper. We also develop analytical models that we compare to our numerical results.Results. When an isothermal eos is used, we show that the peak of the IMF shifts to lower masses with improved numerical resolution. When an adiabatic eos is employed, numerical convergence is obtained. The peak position varies with the eos, and using an analytical model to infer the mass of the first Larson core, we find that the peak position is about ten times its value. By analyzing the stability of nonlinear density fluctuations in the vicinity of a point mass and then summing over a reasonable density distribution, we find that tidal forces exert a strong stabilizing effect and likely lead to a preferential mass several times higher than that of the first Larson core.Conclusions. We propose that in a sufficiently massive and cold cloud, the peak of the IMF is determined by the thermodynamics of the high-density adiabatic gas as well as the stabilizing influence of tidal forces. The resulting characteristic mass is about ten times the mass of the first Larson core, which altogether leads to a few tenths of solar masses. Since these processes are not related to the large-scale physical conditions and to the environment, our results suggest a possible explanation for the apparent universality of the peak of the IMF.
AB - Context. Understanding the origin of the initial mass function (IMF) of stars is a major problem for the star formation process and beyond.Aim. We investigate the dependence of the peak of the IMF on the physics of the so-called first Larson core, which corresponds to the point where the dust becomes opaque to its own radiation.Methods. We performed numerical simulations of collapsing clouds of 1000 M for various gas equations of state (eos), paying great attention to the numerical resolution and convergence. The initial conditions of these numerical experiments are varied in the companion paper. We also develop analytical models that we compare to our numerical results.Results. When an isothermal eos is used, we show that the peak of the IMF shifts to lower masses with improved numerical resolution. When an adiabatic eos is employed, numerical convergence is obtained. The peak position varies with the eos, and using an analytical model to infer the mass of the first Larson core, we find that the peak position is about ten times its value. By analyzing the stability of nonlinear density fluctuations in the vicinity of a point mass and then summing over a reasonable density distribution, we find that tidal forces exert a strong stabilizing effect and likely lead to a preferential mass several times higher than that of the first Larson core.Conclusions. We propose that in a sufficiently massive and cold cloud, the peak of the IMF is determined by the thermodynamics of the high-density adiabatic gas as well as the stabilizing influence of tidal forces. The resulting characteristic mass is about ten times the mass of the first Larson core, which altogether leads to a few tenths of solar masses. Since these processes are not related to the large-scale physical conditions and to the environment, our results suggest a possible explanation for the apparent universality of the peak of the IMF.
KW - ISM
KW - ISM
KW - Stars
KW - Turbulence
KW - clouds
KW - formation
KW - structure
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U2 - 10.1051/0004-6361/201731523
DO - 10.1051/0004-6361/201731523
M3 - Article
AN - SCOPUS:85045188647
SN - 0004-6361
VL - 611
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A89
ER -