A new numerical method for solving radiation driven winds from hot stars

Curé, M.; Rial, Diego

doi:10.1002/asna.200610748

Cited by 11 publications

(13 citation statements)

References 23 publications

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“…We conclude that kinks arise when we use an initial (trial) solution that belongs to a different solution branch in the topology of the m-CAK model (see topological analysis by Curé & Rial 2007).…”

Section: D Time-dependent Wind Solutions For Rotating Starsmentioning

confidence: 90%

“…All singular point are labeled from A to E clockwise starting from the Fast solution eigenvalues as shown in Table A1. This table also show the location of the each singular point in the u, η plane and the value of the determinant of matrix B, that give us the information concerning the topology type of a singular point (see definition of matrix B in section 5.2 from Curé & Rial 2007). In all these cases, the determinant values were negative, thus all singular points are X-type.…”

Section: Appendix A: Topological Analysismentioning

confidence: 98%

“…and ζ = ln(ww ′ ) (A2) Then, from the equation of motion (Eq. 10) plus the regularity and singularity conditions at the singular point, we were able to solve for ζ = ζ (u, η, C ′ ) and then define two new functions, H(u, η, C ′ ) and R(u, η) (see Section 3.4 from Curé & Rial 2007). The location of a singular point is when the following conditions are simultaneously satisfied: Figure A1 shows H(u, η, C ′ ) and R(u, η) functions in terms of u, η and C ′ .…”

Section: Appendix A: Topological Analysismentioning

confidence: 99%

“…In this section we present a topological analysis of a rotational radiation driven wind, this analysis is based in the work of (Curé & Rial 2007), where we presented in detail all the topological theory of radiation driven winds. Here we present a brief summary and the reader might refer to Curé & Rial (2007) for more details.…”

Section: Appendix A: Topological Analysismentioning

confidence: 99%

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Co-existence and switching between fast and Ω-slow wind solutions in rapidly rotating massive stars

Araya

Curé

ud‐Doula

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Most radiatively-driven massive star winds can be modelled with m-CAK theory resulting in so called fast solution. However, those most rapidly rotating among them, especially when the stellar rotational speed is higher than ∼ 75% of the critical rotational speed, can adopt a different solution called Ω-slow solution characterized by a dense and slow wind. Here, in this work we study the transition region of the solutions where the fast solution changes to the Ω-slow. Using both time-steady and time-dependent numerical codes, we study this transition region for different equatorial models of B-type stars. In all the cases, at certain range of rotational speeds, we found a region where the fast and Ω-slow solution can co-exist. We find that the type of solution obtained in this co-existence region depends heavily on the initial conditions of our models. We also test the stability of the solutions within the co-existence region by performing base density perturbations in the wind. We find that under certain conditions, the fast solution can switch to a Ω-slow solution, or vice versa. Such solution switching may be a possible contributor of material injected into the circumstellar environment of Be stars, without requiring rotational speeds near critical values.

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Section: D Time-dependent Wind Solutions For Rotating Starsmentioning

confidence: 90%

Section: Appendix A: Topological Analysismentioning

confidence: 98%

Section: Appendix A: Topological Analysismentioning

confidence: 99%

Section: Appendix A: Topological Analysismentioning

confidence: 99%

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Co-existence and switching between fast and Ω-slow wind solutions in rapidly rotating massive stars

Araya

Curé

ud‐Doula

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…Based on the m-CAK theory, Gormaz-Matamala et al (2019, hereafter Paper I) developed a prescription to derive self-consistent solutions given different sets of stellar parameters for hot massive stars, following the quasi-NLTE treatment for atomic populations of Mazzali & Lucy (1993), the radiation field calculated from Tlusty (Hubeny & Lanz 1995) and the hydrodynamic solutions performed by HydWind (Curé 2004;Curé & Rial 2007). Paper I demonstrated that the prescription provided useful theoretical wind parameters for different sets of temperature, surface gravities, abundances and even the rotational velocity.…”

Section: Introductionmentioning

confidence: 99%

New Solutions to Line-Driven Winds of Hot Massive Stars

Gormaz-Matamala¹,

Curé²,

Cidale

et al. 2016

Proc. IAU

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In the frame of radiation driven wind theory (Castor et al.1975), we present self-consistent hydrodynamical solutions to the line-force parameters (k, α, δ) under LTE conditions. Hydrodynamic models are provided by HydWind (Curé 2004). We evaluate these results with those ones previously found in literature, focusing in different regions of the optical depth to be used to perform the calculations. The values for mass-loss rate and terminal velocity obtained from our calculations are also presented.We also examine the line-force parameters for the case when large changes in ionization throughout the wind occurs (δ-slow solutions, Curé et al.2011).

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New self-consistent wind parameters to fit optical spectra of O-type stars observed with the HERMES spectrograph

Gormaz-Matamala

Curé

Lobel

et al. 2022

A&A

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Aims. We performed a spectral fitting for a set of O-type stars based on self-consistent wind solutions, which provide mass-loss rate and velocity profiles directly derived from the initial stellar parameters. The great advantage of this self-consistent spectral fitting is therefore the reduction of the number of free parameters to be tuned. Methods. Self-consistent values for the line-force parameters (k, α, δ)sc and subsequently for the mass-loss rate, Msc, and terminal velocity, υ∞‚sc, are provided by the m-CAK prescription introduced in Paper I, which is updated in this work with improvements such as a temperature structure T(r) for the wind that are self-consistently evaluated from the line-acceleration. Synthetic spectra were calculated using the radiative transfer code FASTWIND, replacing the classical β-law for our new calculated velocity profiles v(r) and therefore making clumping the only free parameter for the stellar wind. Results. We found that self-consistent m-CAK solutions provide values for theoretical mass-loss rates of the order of the most recent predictions of other studies. From here, we generate synthetic spectra with self-consistent hydrodynamics to fit and obtain a new set of stellar and wind parameters for our sample of O-type stars (HD 192639, 9 Sge, HD 57682, HD 218915, HD 195592, and HD 210809), whose spectra were taken with the high-resolution echelle spectrograph HERMES (R = 85 000). We find a satisfactory global fit for our observations, with a good accuracy for photospheric He I and He II lines and a quite acceptable fit for H lines. Although this self-consistent spectral analysis is currently constrained in the optical wavelength range alone, this is an important step towards the determination of stellar and wind parameters without using a β-law. Based on the variance of the line-force parameters, we establish that our method is valid for O-type stars with Teff ≥ 30 kK and log g ≥ 3.2. Given these results, we expect that the values introduced here are helpful for future studies of the stars constituting this sample, together with the prospect that the m-CAK self-consistent prescription may be extended to numerous studies of massive stars in the future.

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A new numerical method for solving radiation driven winds from hot stars

Cited by 11 publications

References 23 publications

Co-existence and switching between fast and Ω-slow wind solutions in rapidly rotating massive stars

Co-existence and switching between fast and Ω-slow wind solutions in rapidly rotating massive stars

New Solutions to Line-Driven Winds of Hot Massive Stars

New self-consistent wind parameters to fit optical spectra of O-type stars observed with the HERMES spectrograph

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