J/A+A/598/A116 A grid of 1D low-mass star formation models (Vaytet+, 2017)
A grid of one-dimensional low-mass star formation collapse models.
Vaytet N., Haugbolle T.
<Astron. Astrophys. 598, A116 (2017)>
=2017A&A...598A.116V 2017A&A...598A.116V (SIMBAD/NED BibCode)
ADC_Keywords: Models ; Protostars ; YSOs
Keywords: stars: formation - stars: protostars - stars: low-mass -
hydrodynamics - radiative transfer - gravitation
Abstract:
Numerical simulations of star formation are becoming ever more
sophisticated, incorporating new physical processes in increasingly
realistic set-ups. These models are being compared to the latest
observations through state-of-the-art synthetic renderings that trace
the different chemical species present in the protostellar systems.
The chemical evolution of the interstellar and protostellar matter is
very topical, with more and more chemical databases and reaction
solvers available online to the community. The current study was
developed to provide a database of relatively simple numerical
simulations of protostellar collapse as a template library for
observations of cores and very young protostars, and for researchers
who wish to test their chemical modelling under dynamic astrophysical
conditions. It was also designed to identify statistical trends that
may appear when running many models of the formation of low-mass stars
by varying the initial conditions. A large set of 143 calculations of
the gravitational collapse of an isolated sphere of gas with uniform
temperature and a Bonnor-Ebert-like density profile was undertaken
using a 1D fully implicit Lagrangian radiation hydrodynamics code. The
parameter space covered initial masses from 0.2 to 8M☉,
temperatures of 5-30K, and radii 3000-30,000AU. A spread due to
differing initial conditions and optical depths, was found in the
thermal evolutionary tracks of the runs. Within less than an order of
magnitude, all first and second Larson cores had masses and radii
essentially independent of the initial conditions. Radial profiles of
the gas density, velocity, and temperature were found to vary much
more outside of the first core than inside. The time elapsed between
the formation of the first and second cores was found to strongly
depend on the first core mass accretion rate, and no first core in our
grid of models lived for longer than 2000 years before the onset of
the second collapse. The end product of a protostellar cloud collapse,
the second Larson core, is at birth a canonical object with a mass and
radius of about 3Mjup and 8Rjup, independent of its initial
conditions. The evolution sequence which brings the gas to stellar
densities can, however, proceed in a variety of scenarios, on
different timescales or along different isentropes, but each story
line can largely be predicted by the initial conditions.
Description:
We ran 143 1D simulations of gravitationally collapsing Bonnor-Ebert
spheres, varying the initial mass, radius and temperature of the
parent cloud. The properties of the first and second Larson cores are
reported.
The simulation outputs for each run are provided (one separate file
per snapshot), as well as the initial parameters and core properties
in a summary tablec1.dat.
All the data from the simulations (figures and raw data
for every output) are publicly available at this address:
http://starformation.hpc.ku.dk/grid-of-protostars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablec1.dat 279 143 Initial parameters and Larson core properties
runs/* . 143 *Individual simulation outputs
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Note on runs/*: Each run directory has 1.3-1.6G size.
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See also:
http://starformation.hpc.ku.dk/grid-of-protostars : All data
Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Run Run number
9- 19 E11.5 Msun M0 Initial cloud mass
22- 32 E11.5 K T0 Initial cloud temperature
35- 45 E11.5 AU R0 Initial cloud radius
48- 58 E11.5 g/cm3 rhoc Initial cloud central gas density
61- 71 E11.5 --- eps Ratio of Bonnor-Ebert mass to initial cloud mass
74- 84 E11.5 kyr tff1 Free-fall time computed from central density
87- 97 E11.5 kyr tff2 Free-fall time computed from average density
100-110 E11.5 kyr tff3 Modified free-fall time
113-123 E11.5 kyr tsound Cloud sound crossing time
126-136 E11.5 AU R1 First Larson core radius
139-149 E11.5 Msun M1 First Larson core mass
152-162 E11.5 Msun/yr Mdot1 First Larson core mass accretion rate
165-175 E11.5 Lsun Lacc1 First Larson core accretion luminosity
178-188 E11.5 Lsun Lrad1 First Larson core radiative luminosity
191-201 E11.5 yr taufc First Larson core lifetime
204-214 E11.5 AU R2 Second Larson core radius
217-227 E11.5 Msun M2 Second Larson core mass
230-240 E11.5 Msun/yr Mdot2 Second Larson core mass accretion rate
243-253 E11.5 Lsun Lacc2 Second Larson core accretion luminosity
256-266 E11.5 Lsun Lrad2 Second Larson core radiative luminosity
269-279 E11.5 Lsun Lout Luminosity at the grid outer edge
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Description of files in runs/run* subdirectories:
(Byte-by-byte Description of file: runs/run*/*)
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Bytes Format Units Label Explanations
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1- 20 E20.14 cm rc Cell central radius
23- 42 E20.14 cm ri Cell inner radius
44 A1 --- u- Gas velocity sign
45- 64 E20.14 cm/s u Gas velocity
67- 86 E20.14 10-7W/cm3 e Gas internal energy density (erg/cm3)
89-108 E20.14 10-7W/cm3 Er Radiative energy density (erg/cm3)
110 A1 --- Fr- Radiative flux sign
111-130 E20.14 mW/m2 Fr Radiative flux (erg/cm2/s)
133-152 E20.14 g/cm3 rho Gas density
155-174 E20.14 10-7W/cm3 Etot Gas kinetic + internal energy density (erg/cm3)
177-196 E20.14 g Menc Enclosed mass from r=0 to r=ri
199-218 E20.14 cm/s Cs Gas sound speed
221-240 E20.14 K T Gas temperature
243-262 E20.14 g/cm/s P Gas pressure
265-284 E20.14 10-7W/K/g S Gas entropy (erg/K/g)
287-306 E20.14 cm2/g kp Planck mean opacity
309-328 E20.14 cm2/g kr Rosseland mean opacity
331-350 E20.14 --- xH Mass concentration of Hydrogen
353-372 E20.14 --- xH2 Mass concentration of H2
375-394 E20.14 --- xHe Mass concentration of He
397-416 E20.14 --- xHe+ Mass concentration of He+
419-438 E20.14 s t Time
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Acknowledgements:
Neil Vaytet, neil.vaytet(at)nbi.ku.dk
Troels Haugbolle, haugboel(at)nbi.ku.dk
(End) Neil Vaytet [StarPlan, NBI, Denmark], Patricia Vannier [CDS] 04-Nov-2016