J/A+A/702/A9 METUJE wind models of OB stars at Z≤0.1Zo (Krticka+, 2025)
New line-driven wind mass-loss rates for OB stars with metallicities down
to 0.01 Z☉.
Krticka J., Kubat J., Krtickova I.
<Astron. Astrophys. 702, A9 (2025)>
=2025A&A...702A...9K 2025A&A...702A...9K (SIMBAD/NED BibCode)
ADC_Keywords: Models, atmosphere ; Stars, O ; Mass loss
Keywords: stars: early-type - stars: mass-loss - supergiants -
stars: winds, outflows - Local Group - Magellanic Clouds
Abstract:
We provide new line-driven wind models for OB stars with metallicities
down to 0.0 Zo. The models were calculated with our global wind code
METUJE, which solves the hydrodynamical equations from nearly
hydrostatic photosphere to supersonically expanding stellar wind
together with the equations of statistical equilibrium and radiative
transfer equation. The models predict the basic wind parameters,
namely the wind mass-loss rates and terminal velocities just from the
stellar parameters. In general, the wind mass-loss rates decrease with
decreasing metallicity and this relationship steepens for very low
metallicities Z<0.1Zo. Down to metallicities corresponding to the
Magellanic Clouds and even lower, the predicted mass-loss rates
reasonably agree with observational estimates. However, the
theoretical and observational mass-loss rates for very low
metallicities exhibit significant scatter. We show that the scatter of
observational values can be caused by inefficient shock cooling in the
stellar wind, which leaves a considerable fraction of the wind at too
high temperatures with waning observational signatures. The scatter of
theoretical predictions is caused by a low number of lines that
effectively accelerate the wind at very low metallicities.
Description:
We provide new line-driven wind models for luminous OB stars with
metallicities down to 0.01Z☉. The models were calculated with
our global wind code METUJE, which solves the hydrodynamical equations
from nearly hydrostatic photosphere to supersonically expanding
stellar wind. The radiative force accelerating the wind was derived
from the solution of the radiative transfer equation in the comoving
frame. The corresponding ionization and excitation structure was
derived from the kinetic equilibrium equations (NLTE equations).
Wind models for stars with parameters given in Tables 1 and 2 of the
paper calculated using METUJE wind code. Individual files give radial
variations of different variables.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 86 24 Adopted parameters of the model grid of B stars
table2.dat 108 21 Adopted parameters of the model grid of O stars
*/*/*.10 . 128 Hydrodynamic variables of heavy ions
*/*/*.11 . 128 Hydrodynamic variables of H+He
*/*/*.12 . 128 Hydrodynamic variables of electrons
*/*/*.27 . 128 Contribution of individual ions to the
radiative force
*/*/*.28 . 128 Ionization fractions
*/*/*.29 . 128 Level populations
*/*/*.81 . 128 Emergent flux
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Note: The first letters "b" and "o" in the names of the files denote grids
of B and O stars, respectively. The second letter denotes the
metallicity, where "t" stands for 1/10 Zo, "v" stands for 1/30 Zo, and
"x" stands for 1/100 Zo (after 2003ApJS..147..225L 2003ApJS..147..225L).
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See also:
J/A+A/606/A31 : METUJE wind models of O stars from our Galaxy (Krticka+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 Msun M Stellar mass
4- 9 A6 --- Model Model name
11- 14 F4.1 kK Teff Stellar effective temperature
16- 20 F5.1 Rsun R* Stellar radius
22- 29 A8 --- Filest Name of the subdirectory bt with model results
31- 34 I4 km/s Vinft Predicted terminal velocity for Zo/10
36- 42 E7.2 Msun/yr dM/dtt Predicted mass-loss rate for Zo/10
44- 51 A8 --- Filesv Name of the subdirectory bv with model results
53- 56 I4 km/s Vinfv ? Predicted terminal velocity for Zo/30
58- 64 E7.2 Msun/yr dM/dtv ? Predicted mass-loss rate for Zo/30
66- 73 A8 --- Filesx Name of the subdirectory bx with model results
75- 78 I4 km/s Vinfx ? Predicted terminal velocity for Zo/100
80- 86 E7.2 Msun/yr dM/dtx ? Predicted mass-loss rate for Zo/100
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Type Star type
15- 19 A5 --- Model Model name
21- 25 I5 K Teff Stellar effective temperature
27- 30 F4.1 Rsun R* Stellar radius
32- 35 F4.1 Msun M Stellar mass
37- 40 F4.2 [Lsun] logL Stellar luminosity
42- 45 F4.2 --- Gamma Eddington parameter
47- 53 A7 --- Filest Name of the subdirectory ot with model results
55- 58 I4 km/s Vinft Predicted terminal velocity for Zo/10
60- 66 E7.2 Msun/yr dM/dtt Predicted mass-loss rate for Zo/10
68- 74 A7 --- Filesv Name of the subdirectory ov with model results
76- 79 I4 km/s Vinfv Predicted terminal velocity for Zo/30
81- 87 E7.2 Msun/yr dM/dtv Predicted mass-loss rate for Zo/30
89- 95 A7 --- Filesx Name of the subdirectory ox with model results
97-100 I4 km/s Vinfx ? Predicted terminal velocity for Zo/100
102-108 E7.2 Msun/yr dM/dtx ? Predicted mass-loss rate for Zo/100
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Byte-by-byte Description of file: */*/*.10 */*/*.11 */*/*.12
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Bytes Format Units Label Explanations
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1- 4 I4 --- IR Radial grid point number
7- 19 E13.7 cm R Radius
21- 30 F10.0 cm/s Vr Radial velocity
33- 41 E9.3 g/cm3 Rho Density
44- 51 F8.0 K T Temperature
53- 58 F6.3 --- Z Mean relative charge
60- 68 E9.3 Msun/yr dM/dt Mass-loss rate
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Byte-by-byte Description of file: */*/*.27
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Bytes Format Units Label Explanations
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1- 4 I4 --- IR Radial grid point number
6- 15 F10.6 --- R/R* Radius relative to the stellar radius R*
17- 18 I2 --- IG Atomic number
20- 21 I2 --- IZ Ionic number (1 for neutral,
2 for singly ionized, et.)
24- 32 F9.7 --- Fion/Ftot Relative contribution to the line radiative
force in the Sobolev approximation
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Byte-by-byte Description of file: */*/*.28
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Bytes Format Units Label Explanations
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1- 4 I4 --- IR Radial grid point number
7- 19 E13.7 cm R Radius
21- 22 I2 --- IG Atomic number
24- 25 I2 --- IZ Ionic number (1 for neutral,
2 for singly ionized, et.)
28- 31 A4 --- Ele Elemental designation and ionic number
35- 47 E13.7 --- Nion/Nele Number density of a given ion with respect to
the number density of element
49- 61 E13.7 --- U Partition function
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Byte-by-byte Description of file: */*/*.29
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Bytes Format Units Label Explanations
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1- 4 I4 --- IR Radial grid point number
7- 19 E13.7 cm R Radius
21- 22 I2 --- IG Atomic number
24- 25 I2 --- IZ Ionic number (1 for neutral,
2 for singly ionized, et.)
28- 37 A10 --- Level Level designation
41- 53 E13.7 --- Nlev/Nele Number density of ion in a given level with
respect to the number density of element
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Byte-by-byte Description of file: */*/*.81
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Bytes Format Units Label Explanations
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3- 23 E21.15 1/s nu Frequency
25- 47 E23.15 10-7J/cm2 Hnu Eddington flux at the stellar surface
(in erg/cm^2 unit)
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Acknowledgements:
Jiri Krticka, krticka(at)physics.muni.cz
(End) Jiri Krticka [MU, Czech Republic], Patricia Vannier [CDS] 18-Aug-2025