Pith. Sign in

REVIEW

Mass-loss predictions for O and B stars as a function of metallicity

Astrophysics · Submitted 29 Jan 2001 · 47 references

Pith's verdict: A solid, widely used mass-loss recipe, but its single Z^0.85 term is an average that hides real per-temperature spread in the B-supergiant regime.

T0 · AI review

How this review was made: An AI referee (selfhosted/deepseek-v4.1-flash) read the paper on October 29, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

  1. T0 AI review An AI read the paper and answered a fixed list of questions.
  2. T1 Audit Automatic checks that the references and files the paper relies on exist and match.
  3. T2 Compute The paper's code or calculations re-run with the same results.
  4. T3 Formal statement The claims written out in a formal math language a computer can read.
  5. T4 Proof Those claims proved, and the proof checked by computer.

How Pith checks papers →

· 3 major objections · 9 minor · Ask about this paper · The compiled record · Read the full review →
Challenge this review Comment (0) Read on arXiv ↗
Cite ▾
arXiv IDastro-ph/0101509 (version 1)
Pith ID3UN24HLJ, Pith's permanent record of this paper and its review
Citation3), Alex de Koter (2), Henny J.G.L.M. Lamers (1) ((1) Astronomical Institute, Jorick S. Vink (1, London, Medicine, Technology, The Netherlands (2) Astronomical Institute, The Netherlands (3) Imperial College of Science, UK), University of Amsterdam, Utrecht University. "Mass-loss predictions for O and B stars as a function of metallicity." arXiv:astro-ph/0101509 (2001). https://pith.science/paper/3UN24HLJ
Cite this reviewBibTeX for Pith's review of this paper
Claim paper

Why Pith says this

Highlight any text to comment on it.

Referee report
The paper

The paper claims

Mass loss from massive O and B stars follows a single power law in metal abundance over roughly 1/30 to 3 times solar metallicity.

The reading

The paper asks how strongly the winds of massive O and B stars depend on how many heavy elements the star contains. Using a Monte Carlo radiative-transfer wind model that follows photons through the outflow and counts multiple scatterings, the authors compute mass-loss rates across a grid of metallicities, temperatures, luminosities, and wind-speed ratios. They find that over roughly $1/30$ to $3$ times solar metallicity, mass loss follows a single power law in metallicity, with an exponent near $0.85$ when terminal wind speed is held fixed; folding in the cited $v_∞ ∝ Z^{0.13}$ gives $Ṁ ∝ Z^{0.69}$ for hot stars and $Ṁ ∝ Z^{0.64}$ for B supergiants. That matters because evolutionary calculations have often used a square-root dependence, which would underpredict how much mass low-metallicity massive stars retain. The authors package the result as an additive term in their earlier mass-loss recipe and check it against observed Galactic and Small Magellanic Cloud O stars.

What carries the argument

The load-bearing machinery is the Unified Monte Carlo wind model: a model atmosphere with non-LTE level populations supplies the density and temperature structure, then photon packets are followed through about 50-60 shells and more than $10^5$ spectral lines of H through Zn, with multiple scatterings counted, until the radiative momentum transferred matches the wind momentum. This avoids the core-halo split of classical line-driving treatments and lets the authors compute a self-consistent $Ṁ$ for each grid point. The metallicity dependence is extracted as the slope of $log Ṁ$ versus $log(Z/Z_⊙)$ at fixed temperature and wind-speed ratio, and the bi-stability jumps are handled by fitting the characteristic wind density at the jump and converting it to a jump temperature.

Extended reading notes

Core claim

The central claim is that, over $1/30 ≤ Z/Z_⊙ ≤ 3$, the mass-loss rate of massive stars obeys a single power law in metal abundance when the terminal wind speed is held fixed: $Ṁ ∝ Z^{0.85} v_∞^p$, with $p=-1.23$ for stars hotter than about $25{,}000$ K and $p=-1.60$ for B supergiants cooler than that. Feeding in the cited scaling $v_∞ ∝ Z^{0.13}$ turns this into an overall dependence $Ṁ ∝ Z^{0.69}$ for the hot stars and $Ṁ ∝ Z^{0.64}$ for the B supergiants. The exponent is reported as constant across that range, which is what licenses adding a single $+0.85 log(Z/Z_⊙)$ term to the earlier Vink et al. (2000) recipe on both sides of the $25{,}000$ K bi-stability jump. The authors also locate additional jumps caused by iron and carbon recombination and give formulae for their temperatures as functions of wind density.

Load-bearing premise

The load-bearing premise is that the exponent calibrated at $T_{eff}=50{,}000$ K and $v_∞/v_{esc}=2.0$, $m=0.85±0.10$, transfers unchanged to every other temperature and wind-speed ratio, with bi-stability jumps assumed to cancel on average; the paper itself notes that a pure power law may fail at the extremes and that the LMC abundance is uncertain, but the temperature-by-temperature constancy is asserted rather than tabulated.

Editorial extensions

If this is right

  • At $Z/Z_⊙=1/30$, the new exponent predicts an O-star mass-loss rate roughly a factor of ten below solar, where the old square-root rule would give only about a factor of five.
  • Evolutionary calculations that adopt the recipe should retain more envelope mass in low-metallicity massive stars and therefore end with different pre-supernova structures than calculations using $m=1/2$.
  • Population synthesis must include the bi-stability jumps at about $25{,}000$ K, $15{,}000$ K, and $35{,}000$ K; the recipe gives each jump temperature from the characteristic wind density.
  • At low metallicity, where CNO rather than iron dominates the line acceleration near the sonic point, oxygen-based abundance estimates are the appropriate input, and iron-based estimates need the conversion given in Table 5.
  • The publicly available routine lets other workers test the recipe against new low-metallicity observations.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • A natural next test is to run the recipe inside a stellar-evolution code and see whether the lower low-$Z$ mass loss changes the predicted maximum black-hole mass or the stripped-envelope supernova fraction.
  • The $0.85$ exponent is close to the classical force-multiplier estimate $m=(1-α)/(α-δ) ≈ 0.8$; if multiple scattering mainly changes the normalization, the residual scatter in the fits should correlate with iron abundance rather than total $Z$.
  • The LMC comparison improves when one adopts $Z=0.8Z_⊙$ from a single O star; individual stellar abundances for the LMC and SMC samples would turn that post-hoc choice into a real test.
  • Because the carbon jump at $35{,}000$ K appears only at low $Z$ and low wind density, a targeted survey of hot, low-$Z$ dwarfs could look for the terminal-velocity change that the paper leaves open.
Original abstract

We have calculated a grid of massive star wind models and mass-loss rates for a wide range of metal abundances between 1/100 and 10 Z/Zsun. The calculation of this grid completes the Vink et al. (2000) mass-loss recipe with an additional parameter Z. We have found that the exponent of the power law dependence of mass loss vs. metallicity is constant in the range between 1/30 and 3 Z/Zsun. The mass-loss rate scales as Mdot \propto Z^0.85 Vinf^p with p = -1.23 for stars with Teff \ga 25000 K, and p = -1.60 for the B supergiants with Teff \la 25000 K. Taking also into account the metallicity dependence of Vinf, using the power law dependence Vinf \propto Z^0.13 from Leitherer et al. (1992), the overall result of mass loss as a function of metallicity can be represented by Mdot \propto Z^0.69 for stars with Teff \ga 25000 K, and Mdot \propto Z^0.64 for B supergiants with Teff \la 25000 K. Our mass-loss predictions are successful in explaining the observed mass-loss rates for Galactic and Small Magellanic Cloud O-type stars, as well as in predicting the observed Galactic bi-stability jump. Hence, we believe that our predictions are reliable and suggest that our mass-loss recipe be used in future evolutionary calculations of massive stars at different metal abundance. A computer routine to calculate mass loss is publicly available.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 6,586 input tokens.

What the abstract itself states, as probabilities: claims first 0.08 · states limitation 0.21 · human participants 0.01 · controlled comparison 0.08 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.88 · mentions code or data availability 0.97.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

We have calculated a grid of massive star wind models and mass-loss rates for a wide range of metal abundances between 1/100 and 10 Z/Zsun. The calculation of this grid completes the Vink et al. (2000) mass-loss recipe with an additional parameter Z. We have found that the exponent of the power law dependence of mass loss vs. metallicity is constant in the range between 1/30 and 3 Z/Zsun. The mass-loss rate scales as Mdot \propto Z^0.85 Vinf^p with p = -1.23 for stars with Teff \ga 25000 K, and p = -1.60 for the B supergiants with Teff \la 25000 K. Taking also into account the metallicity dependence of Vinf, using the power law dependence Vinf \propto Z^0.13 from Leitherer et al. (1992), the overall result of mass loss as a function of metallicity can be represented by Mdot \propto Z^0.69 for stars with Teff \ga 25000 K, and Mdot \propto Z^0.64 for B supergiants with Teff \la 25000 K. Our mass-loss predictions are successful in explaining the observed mass-loss rates for Galactic and Small Magellanic Cloud O-type stars, as well as in predicting the observed Galactic bi-stability jump. Hence, we believe that our predictions are reliable and suggest that our mass-loss recipe be used in future evolutionary calculations of massive stars at different metal abundance. A computer routine to calculate mass loss is publicly available.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 We have calculated a grid of massive star wind models and mass-loss rates for a wide range of metal abundances between 1/100 and 10 Z/Zsun. contribution 0.72 0.97 0.05 asserted 1.00
s1 The calculation of this grid completes the Vink et al. (2000) mass-loss recipe with an additional parameter Z. contribution 0.76 0.74 0.08 asserted 1.00
s2 We have found that the exponent of the power law dependence of mass loss vs. metallicity is constant in the range between 1/30 and 3 Z/Zsun. result 1.00 0.96 0.19 asserted 1.00
s3 The mass-loss rate scales as Mdot \propto Z^0.85 Vinf^p with p = -1.23 for stars with Teff \ga 25000 K, and p = -1.60 for the B supergiants with Teff \la 25000 K. result 1.00 0.91 0.18 asserted 1.00
s4 Taking also into account the metallicity dependence of Vinf, using the power law dependence Vinf \propto Z^0.13 from Leitherer et al. (1992), the overall result of mass loss as a function of metallicity can be represented by Mdot \propto Z^0.69 for stars with Teff \ga 25000 K, and Mdot \propto Z^0.64 for B supergiants with Teff \la 25000 K. result 1.00 0.66 0.37 asserted 0.99
s5 Our mass-loss predictions are successful in explaining the observed mass-loss rates for Galactic and Small Magellanic Cloud O-type stars, as well as in predicting the observed Galactic bi-stability jump. result 0.84 0.83 0.32 asserted 1.00
s6 Hence, we believe that our predictions are reliable and suggest that our mass-loss recipe be used in future evolutionary calculations of massive stars at different metal abundance. interpretation 0.52 0.35 0.55 hedged possibility 0.81
s7 A computer routine to calculate mass loss is publicly available. contribution 0.81 0.57 0.03 asserted 1.00

What kind of paper the classifier reports this is: simulation study 0.66 · evidence from simulation or computation 1.00.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. Continued. Series of M˙ (Z) calculations with Γe = 0.434 (log L/L⊙ = 6.0). The calculated mass loss as a function of Teff for seven metallicities in the range Z/Z⊙ = 1/100 - 10. The metal abundance is indicated in the legend at the upper part of each panel (k-q). The values for (v∞/vesc) are indicated in the legend of the last panel (q)
Figure 2. Characteristic density hρi at the bi-stability jump around 25 000 K as a function of Z. An explanation for the different symbols is given in the legend. The solid line indicates the best linear fit through the average jumps parameters for log hρi. 5.1. The bi-stability jump at Teff ≃ 25 000 K All panels show a bi-stability jump around Teff ≃ 25 000 K. Here, Fe iv recombines to Fe iii and as the latter ion is a more efficient line driver than the first, the acceleration in the lower part of the wind increases. This results in an upward jump in M˙ of about a factor of five and…
Figure 3. Characteristic density log hρi and Teff of the bi￾stability jump around Teff = 25 000 K. An explanation for the different symbols is given in the legend. The solid line represents the best linear fit through the average jump parameters log hρi and Teff. (Z/Z⊙), a linear fit is plotted. This is the solid line in
Figure 4. The relative contribution to the line acceleration for models with (v∞/vesc) = 2.0, log L∗/L⊙ = 5.5 and M∗ = 40M⊙. The solid lines show the contribution of Fe lines. The dotted line is the contribution by C, N and O. The dashed line shows the contribution by H and He lines. (a) and (b) give the contribution for solar Z at resp. v = vsound and at v = 0.5v∞. (c) and (d) give the contribution for (Z/Z⊙) = 1/30 at resp. v = vsound and at v = 0.5v∞. our mass loss recipe will still yield the proper mass-loss rates. Only in those cases where the observed metallic￾ity were determined from…
Figure 5. The M˙ (Z) dependence for three cases of Γe. In all three panels, the dashed lines indicate the best linear fit through the models at different Z. Note that at Γe = 0.130 the lowest Z model is not included in the fit, due to the presence of a bi-stability jump. All models have Teff = 50 000 K and constant (v∞/vesc) = 2.0. The values of Γe are indicated in the legends
Figure 6. Comparison between theoretical and observational M˙ for O stars in the LMC. The upper panel is for an adopted ZLMC = 0.28Z⊙ and the lower panel is for an adopted metallicity ZLMC = 0.8Z⊙. The Puls et al. (1996) Hα rates and de de Koter rates are indicated with different symbols. The dashed lines are one-to-one rela￾tions, tools for convenient comparison between observa￾tions and theory accurately known. What complicates a meaningful com￾parison is that there are differences in the observed stellar and nebular abundances. Additionally, there are abun￾dance gradients present in these…
Figure 7. shows the comparison between observed mass￾loss rates and our predictions for the sample of the SMC stars. The figure shows a reasonable agreement between predictions and observations. We admit that there is quite a large scatter (0.55 dex) for which there may be several reasons. The important point at this stage is that the com￾parison with the SMC data yields good average agreement and thus yields support to the reliability of our mass loss recipe at metallicities other than solar. For a test of our mass-loss recipe at extremely low Z, say Z/Z⊙ < 1/10, we will have to await new…

Figures reproduced from arXiv:astro-ph/0101509 by the authors.

References
How later papers used it

481 later papers cite it

Evidence: substantial. 460 of the citing papers share no author with it, and 259 of those carry a confident label from Pith's citation classifier.

Pith read 40 of the 863 citing sentences, choosing only those whose citation markers point at this paper alone, and wrote the paraphrases from them. The summary, the counts, the evidence level, the links and the quotes come from code; the summary counts the papers listed below. A later paper is listed under a label when Pith's citation classifier gives one of its sentences that label at probability 0.8 or more (0.95 for support), Pith's reading finds that the citing paper itself did it, and a second check confirms the paraphrase against the sentence. This section lists uses only. It does not list criticism or disagreement, so their absence here says nothing about how the paper has been received. Papers that share an author with this one are listed apart, under "By the same authors". A quote is the citing authors' own sentence, shown when their paper's licence is CC BY, CC BY-SA or CC0. JSON

Uses its method or tool 16 of 225 papers with this label · 1 by the same authors

By the same authors

Uses its data or values 1 of 27 papers with this label
Compares with it 1 of 30 papers with this label · 1 by the same authors

By the same authors

How the literature uses it

69 arXiv papers cite this in 155 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 69 sentences without a confident label

Contests it 6 papers
Uses its method or tool 27 papers
Uses its data or values 4 papers
Compares with it 10 papers
Cites it as support 1 paper
Cites it as background 10 papers

Discussion

Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.