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STARFORGE: the effects of protostellar outflows on the IMF

Guszejnov, Dávid and Grudić, Michael Y. and Hopkins, Philip F. and Offner, Stella S. R. and Faucher-Giguère, Claude-André (2021) STARFORGE: the effects of protostellar outflows on the IMF. Monthly Notices of the Royal Astronomical Society, 502 (3). pp. 3646-3663. ISSN 0035-8711. doi:10.1093/mnras/stab278.

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The initial mass function (IMF) of stars is a key quantity affecting almost every field of astrophysics, yet it remains unclear what physical mechanisms determine it. We present the first runs of the STAR FORmation in Gaseous Environments project, using a new numerical framework to follow the formation of individual stars in giant molecular clouds (GMCs) using the GIZMO code. Our suite includes runs with increasingly complex physics, starting with isothermal ideal magnetohydrodynamics (MHD) and then adding non-isothermal thermodynamics and protostellar outflows. We show that without protostellar outflows the resulting stellar masses are an order of magnitude too high, similar to the result in the base isothermal MHD run. Outflows disrupt the accretion flow around the protostar, allowing gas to fragment and additional stars to form, thereby lowering the mean stellar mass to a value similar to that observed. The effect of jets upon global cloud evolution is most pronounced for lower mass GMCs and dense clumps, so while jets can disrupt low-mass clouds, they are unable to regulate star formation in massive GMCs, as they would turn an order unity fraction of the mass into stars before unbinding the cloud. Jets are also unable to stop the runaway accretion of massive stars, which could ultimately lead to the formation of stars with masses >500M⊙⁠. Although we find that the mass scale set by jets is insensitive to most cloud parameters (i.e. surface density, virial parameter), it is strongly dependent on the momentum loading of the jets (which is poorly constrained by observations) as well as the temperature of the parent cloud, which predicts slightly larger IMF variations than observed. We conclude that protostellar jets play a vital role in setting the mass scale of stars, but additional physics are necessary to reproduce the observed IMF.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemGIZMO Code
Guszejnov, Dávid0000-0001-5541-3150
Grudić, Michael Y.0000-0002-1655-5604
Hopkins, Philip F.0000-0003-3729-1684
Offner, Stella S. R.0000-0003-1252-9916
Faucher-Giguère, Claude-André0000-0002-4900-6628
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 January 26. Received 2021 January 26; in original form 2020 October 26. Published: 02 February 2021. DG is supported by the Harlan J. Smith McDonald Observatory Postdoctoral Fellowship. MYG is supported by a CIERA Postdoctoral Fellowship. Support for PFH was provided by NSF Collaborative Research Grants 1715847 and 1911233, NSF CAREER grant 1455342, and NASA grants 80NSSC18K0562 and JPL 1589742. SSRO is supported by NSF Career Award AST-1650486 and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. C-AFG is supported by NSF through grant AST-1715216 and CAREER award AST-1652522; by NASA through grant 17-ATP17-0067; and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. This work used computational resources provided by XSEDE allocation AST-190018, the Frontera allocation AST-20019, and additional resources provided by the University of Texas at Austin and the Texas Advanced Computing Center (TACC; Data Availability: The data supporting the plots within this article are available on reasonable request to the corresponding authors. A public version of the GIZMO code is available at∼phopkins/Site/GIZMO.html.
Group:Astronomy Department, TAPIR
Funding AgencyGrant Number
McDonald ObservatoryUNSPECIFIED
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
University of Texas at AustinUNSPECIFIED
Texas Advanced Computing Center (TACC)UNSPECIFIED
Subject Keywords:MHD– turbulence – stars: formation – stars: jets – stars: luminosity function, mass function
Issue or Number:3
Record Number:CaltechAUTHORS:20210602-104241885
Persistent URL:
Official Citation:Dávid Guszejnov, Michael Y Grudić, Philip F Hopkins, Stella S R Offner, Claude-André Faucher-Giguère, STARFORGE: the effects of protostellar outflows on the IMF, Monthly Notices of the Royal Astronomical Society, Volume 502, Issue 3, April 2021, Pages 3646–3663,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109342
Deposited By: Tony Diaz
Deposited On:02 Jun 2021 18:25
Last Modified:02 Jun 2021 18:25

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