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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 (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:
FileName Lrecl Records Explanations
ReadMe 80 . This file isochron.dat 53 256 *Isochrones data tracks.dat 61 3264 Evolutionary tracks for 9 models
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)
Byte-by-byte Description of file: isochron.dat
Bytes Format Units Label Explanations
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
Byte-by-byte Description of file: tracks.dat
Bytes Format Units Label Explanations
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
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
Acknowledgements: Kunimoto Masannobu, kunitomo.masanobu(at)c.mbox.nagoya-u.ac.jp
(End) Patricia Vannier [CDS] 06-May-2016
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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