J/A+A/599/A49 Pre-main sequence stars evolutionary models (Kunitomo+, 2017)
Revisiting the pre-main sequence evolution of stars.
I. Importance of accretion efficiency and deuterium abundance.
Kunitomo M., Guillot, Takeuchi, Ida S.
<Astron. Astrophys. 599, A49 (2017)>
=2017A&A...599A..49K 2017A&A...599A..49K (SIMBAD/NED BibCode)
ADC_Keywords: Models, evolutionary ; Abundances ; Stars, pre-main sequence
Keywords: stars: formation - stars: pre-main sequence - stars: low-mass -
accretion, accretion disks - stars: evolution -
Hertzsprung-Russell and C-M diagrams
Abstract:
Protostars grow from the first formation of a small seed and
subsequent accretion of material. Recent theoretical work has shown
that the pre-main-sequence (PMS) evolution of stars is much more
complex than previously envisioned. Instead of the traditional steady,
one-dimensional solution, accretion may be episodic and not
necessarily symmetrical, thereby affecting the energy deposited inside
the star and its interior structure.
Given this new framework, we want to understand what controls the
evolution of accreting stars.
We use the MESA stellar evolution code with various sets of
conditions. In particular, we account for the (unknown) efficiency of
accretion in burying gravitational energy into the protostar through a
parameter, ksi, and we vary the amount of deuterium present.
We confirm the findings of previous works that, in terms of
evolutionary tracks on an Hertzprung-Russell (H-R) diagram, the
evolution changes significantly with the amount of energy that is lost
during accretion. We find that deuterium burning also regulates the
PMS evolution. In the low-entropy accretion scenario, the evolutionary
tracks in the H-R diagram are significantly different from the
classical tracks and are sensitive to the deuterium content. A
comparison of theoretical evolutionary tracks and observations allows
us to exclude some cold accretion models (ksi∼0) with low deuterium
abundances.
Description:
We use the MESA stellar evolution code with various sets of
conditions. In particular, we account for the (unknown) efficiency of
accretion in burying gravitational energy into the protostar through a
parameter, ksi, and we vary the amount of deuterium present.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
isochron.dat 53 256 *Isochrones data
tracks.dat 61 3264 Evolutionary tracks for 9 models
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Note on isochron.dat: Settings:
Initial mass: 0.01Msun
Mass accretion rate: 1e-5Msun/yr
Uniform heat distribution (See Sect. 2.6)
X=0.7004553948, Y=0.2794811789, Z=0.0200634263
alpha_MLT=1.9050629261 (Mixing-length parameter)
f_ov=0.0119197042 (Overshooting parameter)
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Byte-by-byte Description of file: isochron.dat
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Bytes Format Units Label Explanations
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2- 6 F5.3 Rsun Rini Initial radius
8- 11 F4.2 --- xi Efficiency if accretion heating (See Eq. 2)
13- 17 F5.3 Msun Mfin Final mass
19- 20 I2 10-6 XD Deuterium content in parts per million
22- 25 F4.1 Myr Age Age
27- 35 F9.7 [K] logTeff Effective temperature
36- 44 F9.6 [Lsun] logL Luminosity
46- 53 F8.6 --- R Radius
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Byte-by-byte Description of file: tracks.dat
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Bytes Format Units Label Explanations
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2- 6 F5.3 Rsun Rini Initial radius (1)
8- 11 F4.2 --- xi Efficiency if accretion heating (See Eq. 2) (1)
13- 17 F5.3 Msun Mfin Final mass
19- 20 I2 10-6 XD Deuterium content in parts per million (1)
22- 33 E12.7 Myr Age Age
35- 42 F8.6 [K] logTeff Effective temperature
44- 52 F9.6 [Lsun] logL Luminosity
54- 61 F8.6 --- R Radius
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Note (1): Models presented:
Rini=1.5, xi=0, XD=20
Rini=1.5, xi=0.05, XD=20
Rini=1.5, xi=0.1, XD=20
Rini=1.5, xi=0.5, XD=20
Rini=3, xi=0.1, XD=20
Rini=0.25, xi=0, XD=20
Rini=0.25, xi=0.1, XD=20
Rini=1.5, xi=0, XD=35
Rini=1.5, xi=0.5, XD=35
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Acknowledgements:
Kunimoto Masannobu, kunitomo.masanobu(at)c.mbox.nagoya-u.ac.jp
(End) Patricia Vannier [CDS] 06-May-2016