J/A+A/693/A68 Convective turnover times of disk-locking stars (Landin+, 2025)
The impact of disk-locking on convective turnover times of low-mass
pre-main sequence and main sequence stars.
Landin N.R., Mendes L.T.S., Vaz L.P.R, Alencar S.H.P.
<Astron. Astrophys. 693, A68 (2025)>
=2025A&A...693A..68L 2025A&A...693A..68L (SIMBAD/NED BibCode)
ADC_Keywords: Models, evolutionary ; Stars, pre-main sequence
Keywords: convection - stars: activity - stars: evolution -
stars: pre-main sequence - stars: rotation
Abstract:
The impact of disk-locking on the stellar properties related to
magnetic activity from the theoretical point of view is investigated.
We use the ATON stellar evolution code to calculate theoretical values
of convective turnover times (tauc) and Rossby numbers (Ro, the
ratio between rotation periods and tauc) for pre-main sequence
(pre-MS) and main sequence (MS) stars.
We investigate how tauc varies with the initial rotation period and
with the disk lifetime, using angular momentum conserving models and
models simulating the disk-locking mechanism. In the latter case, the
angular velocity is kept constant during a given locking time to mimic
the magnetic locking effects of a circumstellar disk. The local
convective turnover times generated with disk-locking models are
shorter than those obtained with angular momentum conserving models.
The differences are smaller in the early pre-MS, increase with stellar
age, and become more accentuated for stars with M≥1M_☉ and ages
greater than 100Myr. Our new values of tauc are used to estimate Ro
for a sample of stars selected from the literature in order to
investigate the rotation-activity relationship. We fit the data with a
two-part power-law function and find the best fitting parameters of
this relation. The differences found between both sets of models
suggest that the star's disk-locking phase properties affect its
Rossby number and its position in the rotation-activity diagram. Our
results indicate that the dynamo efficiency is lower for stars that
had undergone longer disk-locking phases.
Description:
These data present two sets of new pre-main sequence evolutionary
tracks (including local and global convective turnover times, Rossby
numbers, rotation periods, and fractional masses of the radiative
core) for masses in the range of 0.1 to 1.2 solar masses in 0.1 solar
masses steps. In the first set of models (AMC models), we consider
conservation of angular momentum throughout all stellar evolution. In
the second set (DL models), we simulate the disk-locking mechanism, by
considering an evolution with constant angular velocity during the
first evolutionary stages followed by conservation of angular
momentum.
The tracks were generated with a modified version of D'Antona &
Mazzitelli's code (the ATON code) described in Ventura et al.
(1998A&A...334..953V 1998A&A...334..953V). In this new version we included non-gray
boundary conditions (Landin et al., 2006A&A...456..269L 2006A&A...456..269L), rotation
with local conservation of angular momentum in the whole star (Mendes
et al., 1999A&A...341..174M 1999A&A...341..174M), disk-locking mechanism (Landin et al.,
2016A&A...586A..96L 2016A&A...586A..96L) and convective turnover times calculations. Local
convective turnover times calculations of partially convective stars
were performed at one-half of a mixing length above the base of the
convective zone. For fully convective stars we used an alternative
radial position given by Landin et al., 2023MNRAS.519.5304L 2023MNRAS.519.5304L. All
models were computed with solar metallicity (X=0.7155, Y=0.2703,
Z=0.0142, 2009,ARA&A...47..481A) and alpha=2.0 (mixing length theory
parameter).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tab1-dl.dat 77 7200 Evolutionary tracks obtained with DL models
tab1-amc.dat 77 7200 Evolutionary tracks obtained with AMC models
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See also:
J/A+A/510/A46 : Pre-main sequence evolutionary tracks (Landin+, 2010)
J/MNRAS/519/5304 : Rossby numbers of convective stars (Landin+, 2023)
Byte-by-byte Description of file: tab1-dl.dat tab1-amc.dat
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Bytes Format Units Label Explanations
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1- 3 F3.1 Msun Mass Mass
5- 11 F7.4 [yr] logAge Age of model
13- 19 F7.4 [Lsun] logL Bolometric luminosity
21- 26 F6.4 [K] logTeff Effective temperature
28- 33 F6.3 [cm/s2] loggeff Effective gravity
35- 41 F7.4 [d] logtauc Local convective turnover time
43- 49 F7.4 [d] logtaug Global convective turnover time
51- 59 F9.4 d Prot Rotation period
61- 68 F8.4 --- Ro Rossby number
70- 77 F8.4 Msun Mrad Mass of the radiative core
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Acknowledgements:
Natalia Landin, nlandin(at)ufv.br
References:
Landin et al., 2006A&A...456..269L 2006A&A...456..269L, Non-gray rotating stellar models and
the evolutionary history of the Orion Nebular Cluster
(End) Natalia Landin [Fed. Uni. of Vicosa], Patricia Vannier [CDS] 19-Nov-2024