pith. sign in

arxiv: 2606.03192 · v1 · pith:57HFGSVAnew · submitted 2026-06-02 · 🌌 astro-ph.CO

Fifty years of primordial helium abundances: A statistical reanalysis

Nabil Husain , Richard de Grijs , Giuseppe Bono This is my paper

Pith reviewed 2026-06-28 09:14 UTC · model grok-4.3

classification 🌌 astro-ph.CO
keywords primordial helium abundanceY_pBig Bang nucleosynthesisextragalactic H II regionschange-point detectiondata dependenceobservational reanalysiscosmological constraints
0
0 comments X

The pith

A reanalysis of 143 published Y_p values shows long-term convergence in primordial helium abundances, interrupted by change points, with many measurements sharing underlying observational datasets.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper assembles every reported primordial helium mass fraction determination from the late 1960s through 2022 and subjects the collection to statistical scrutiny. It documents a steady tightening of published values around a common number, interrupted by detectable shifts in the mid-2000s and early 2010s. At the same time it demonstrates that a substantial fraction of the extragalactic H II-region results rest on repeated use or partial reprocessing of the same raw spectra and calibrations, so the true number of independent constraints is smaller than the headline count of 143. The authors note that this dependence does not overturn the agreement between modern Y_p and standard Big Bang nucleosynthesis, yet it supplies necessary context for any future synthesis of the measurements.

Core claim

Compilation of 143 published Y_p determinations reveals statistically significant long-term convergence punctuated by change points in the mid-2000s and early 2010s; many extragalactic H II-region values are not fully independent because they rely on re-analyses or partial reuse of a limited number of observational datasets, thereby lowering the effective number of independent constraints while leaving the overall consistency with standard cosmology intact.

What carries the argument

The compiled time series of 143 Y_p values together with change-point detection applied to that series.

If this is right

  • The effective number of independent Y_p constraints is lower than the raw count of published papers.
  • Recent high-precision results must be interpreted with explicit allowance for shared data provenance.
  • Any meta-analysis that treats each published value as statistically independent will overstate the combined precision.
  • Methodological homogeneity across re-analyses contributes to the observed tightening of the reported values.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Future campaigns aiming to tighten cosmological constraints will need to secure genuinely new spectra rather than reprocess existing ones.
  • The same dependence issue likely affects other primordial abundance tracers that draw from overlapping H II-region samples.
  • Change-point locations may mark the adoption of particular atomic data or calibration pipelines rather than purely statistical fluctuations.

Load-bearing premise

The assembled list of 143 values captures every relevant published determination without selection bias and the change-point algorithm correctly flags genuine shifts rather than artifacts of the chosen statistical model.

What would settle it

Publication of a sizable set of new Y_p measurements drawn from completely distinct observational datasets that fall outside the narrow range established by the post-2010s cluster.

Figures

Figures reproduced from arXiv: 2606.03192 by Giuseppe Bono, Nabil Husain, Richard de Grijs.

Figure 1
Figure 1. Figure 1: (Top) Published 𝑌p values with their uncertainties (where available) as a function of publication date, colour-coded by tracer. The Planck 2018 value, 𝑌p = 0.2463 (horizontal dotted line) is included for visual benchmarking. CMB: Cosmic Microwave Background; RRLs: Radio recombination lines; GCs: Globular clusters. (Middle) As the top panel but for the Hii-region- and CMB-based analyses only. The publicatio… view at source ↗
Figure 2
Figure 2. Figure 2: (Top) Cumulative number of primordial helium abundance determi￾nations as a function of publication year. Blue bars show the total number of measurements, whereas the orange bars indicate the subset classified as ‘new’. The divergence between the two curves underscores the increasing contribution of re-analyses and partially overlapping data. (Bottom) Breakdown of the compi￾lation by data independence. Eac… view at source ↗
Figure 3
Figure 3. Figure 3: 𝑌p values and their uncertainties as a function of publication date published by three distinct author groups: Peimbert et al. (red), Izotov and Thuan (blue) and Aver and collaborators (green). The Planck 2018 value, 𝑌p = 0.2463 is included as a horizontal dotted line for visual benchmarking. compared with known developments in observational capabili￾ties, atomic data and cosmological constraints to assess… view at source ↗
Figure 4
Figure 4. Figure 4: Weighted cumulative means as a function of publication date for (left) all published 𝑌p values and (right) 𝑌p values based on Hii region-based analysis only. of identified change points therefore requires external physical and historical context, which we address in the following section. Note that publication date is used here as a proxy for the temporal evolu￾tion of the field. In practice, observational… view at source ↗
Figure 5
Figure 5. Figure 5: (left) Cluster means with their standard deviations indicated. (right) Comparison of methods. differences. By contrast, representations based on within-cluster dispersion reveal that a substantial component of the scatter arises from dataset-level systematics, consistent with the hierarchical structure of the compiled sample. 4. Discussion 4.1. Long-term trends and convergence in published 𝑌p values The mo… view at source ↗
read the original abstract

The primordial helium mass fraction, $Y_\mathrm{p}$, is a key observational pillar of Big Bang nucleosynthesis and a sensitive probe of early-Universe physics. Over the past several decades, numerous observational $Y_\mathrm{p}$ determinations have been published using a wide range of astrophysical tracers and cosmological techniques. Although recent measurements exhibit striking convergence and increasingly small uncertainties, the statistical and historical context of this consensus has not been examined systematically. Here, we compile and analyse a comprehensive dataset of observational $Y_\mathrm{p}$ determinations published between the late-1960s and 2022. The final sample comprises 143 reported values spanning multiple tracers. We find clear evidence for long-term convergence in published $Y_\mathrm{p}$ values, punctuated by statistically significant change points in the mid-2000s and early 2010s. Careful examination reveals that many extragalactic H{\sc ii}-region determinations are not fully independent, relying on re-analyses or partial reuse of a limited number of observational datasets. This reduces the effective number of independent constraints and provides important context for interpreting the precision of recent results. Our findings do not challenge the overall consistency of modern $Y_\mathrm{p}$ determinations with standard cosmology, but they underscore the importance of accounting for data dependence, methodological homogeneity and historical evolution when synthesising measurements.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The paper compiles a dataset of 143 published observational determinations of the primordial helium mass fraction Y_p from the late 1960s to 2022 across multiple tracers. It reports clear long-term convergence in the values, interrupted by statistically significant change points in the mid-2000s and early 2010s, and documents that many extragalactic H II-region measurements are not fully independent due to re-analyses or reuse of a limited set of underlying observational datasets, thereby reducing the effective number of independent constraints.

Significance. If the change-point results and independence assessment prove robust, the work supplies useful historical and statistical context for interpreting the apparent precision of modern Y_p measurements and for properly weighting constraints in Big Bang nucleosynthesis analyses. The emphasis on data dependence is a constructive contribution to the field.

major comments (3)
  1. [Statistical analysis / change-point section] The change-point detection procedure is not described: no algorithm, handling of uncertainties, priors on variance, or robustness checks (alternative algorithms, leave-one-dataset-out tests, or sensitivity to exclusion criteria) are provided. This is load-bearing for the central claim of statistically significant change points in the mid-2000s and early 2010s.
  2. [Dataset construction section] The compilation rules for the 143-value sample are unspecified (search strategy, inclusion/exclusion criteria, handling of updates or re-analyses). Without this, it is impossible to assess whether the sample is exhaustive or free of selection effects, which directly affects the convergence and change-point results.
  3. [Independence / H II-region analysis section] The independence analysis notes reuse of a limited number of observational datasets but provides no quantitative estimate of effective independent sample size nor demonstrates how this dependence propagates into the reported convergence or change-point statistics.
minor comments (2)
  1. [Abstract] The abstract would be strengthened by a one-sentence description of the change-point method and the criteria used to identify non-independence.
  2. [Figures and tables] Figure captions and table legends should explicitly state how uncertainties are displayed and whether points are weighted by reported errors.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their constructive report and for recognizing the potential value of the historical and statistical context provided by our compilation. We address each major comment below and commit to revisions that strengthen the methodological transparency without altering the core findings.

read point-by-point responses

  1. Referee: [Statistical analysis / change-point section] The change-point detection procedure is not described: no algorithm, handling of uncertainties, priors on variance, or robustness checks (alternative algorithms, leave-one-dataset-out tests, or sensitivity to exclusion criteria) are provided. This is load-bearing for the central claim of statistically significant change points in the mid-2000s and early 2010s.

    Authors: We agree that the change-point section requires substantially more detail. The manuscript currently states the existence of the change points but does not fully specify the detection algorithm, uncertainty propagation, or prior choices. We will expand this section to describe the exact procedure (including the statistical model employed), how measurement uncertainties are incorporated, the priors used, and the results of robustness tests such as alternative algorithms and leave-one-out analyses. These additions will be placed in a dedicated subsection with accompanying code or pseudocode where appropriate. revision: yes

  2. Referee: [Dataset construction section] The compilation rules for the 143-value sample are unspecified (search strategy, inclusion/exclusion criteria, handling of updates or re-analyses). Without this, it is impossible to assess whether the sample is exhaustive or free of selection effects, which directly affects the convergence and change-point results.

    Authors: The referee is correct that the current text does not provide an explicit account of the literature search and selection protocol. We will add a new subsection detailing the search strategy (databases, keywords, date range), the precise inclusion and exclusion criteria, and the procedure for handling duplicate or updated measurements. This will allow readers to evaluate potential selection effects and to reproduce the sample construction. revision: yes

  3. Referee: [Independence / H II-region analysis section] The independence analysis notes reuse of a limited number of observational datasets but provides no quantitative estimate of effective independent sample size nor demonstrates how this dependence propagates into the reported convergence or change-point statistics.

    Authors: We acknowledge that the independence discussion remains qualitative. While the manuscript identifies the reuse of underlying datasets, it does not quantify the effective number of independent measurements or propagate the dependence into the convergence and change-point results. We will revise this section to include a quantitative estimate (e.g., by counting unique observational datasets and deriving an effective sample size) and will discuss the implications for the reported statistics, including any sensitivity analyses that account for the dependence structure. revision: yes

Circularity Check

0 steps flagged

No circularity: direct statistical analysis of external published values

full rationale

The paper compiles a dataset of 143 externally published Y_p determinations spanning 1960s-2022 and applies standard statistical procedures (change-point detection, independence assessment) to identify convergence trends. No equations or derivations reduce the reported change points or convergence to quantities fitted from the same dataset by construction. The analysis treats the input values as given observations from the literature; results are outputs of applying external methods to independent data, with no self-definitional loops, fitted-input predictions, or load-bearing self-citations that collapse the central claims. This is a self-contained meta-analysis against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Abstract-only review yields no explicit free parameters, invented entities, or non-standard axioms; the work relies on standard statistical assumptions for time-series change-point detection and on the completeness of the literature search.

axioms (1)
  • domain assumption Published Y_p values form a suitable time series for change-point analysis without systematic publication bias dominating the detected shifts
    Implicit in the claim of statistically significant change points in the mid-2000s and early 2010s.

pith-pipeline@v0.9.1-grok · 5769 in / 1297 out tokens · 24506 ms · 2026-06-28T09:14:29.347105+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

146 extracted references · 121 canonical work pages · 61 internal anchors

  1. [1]

    Peebles, P. J. E. , title = ". , year =

  2. [2]

    and Fowler, William A

    Wagoner, Robert V. and Fowler, William A. and Hoyle, F. , title = ". , year = 1967, month = apr, volume =. doi:10.1086/149126 , adsurl =

    work page doi:10.1086/149126 1967

  3. [3]

    Big Bang Nucleosynthesis: 2015

    Cyburt, Richard H. and Fields, Brian D. and Olive, Keith A. and Yeh, Tsung-Han , title = ". Reviews of Modern Physics , year = 2016, month = jan, volume =. doi:10.1103/RevModPhys.88.015004 , archivePrefix =. 1505.01076 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1103/revmodphys.88.015004 2016

  4. [4]

    Annual Review of Nuclear and Particle Science , year = 2007, month = nov, volume =

    Steigman, Gary , title = ". Annual Review of Nuclear and Particle Science , year = 2007, month = nov, volume =. doi:10.1146/annurev.nucl.56.080805.140437 , archivePrefix =. 0712.1100 , primaryClass =

    work page doi:10.1146/annurev.nucl.56.080805.140437 2007

  5. [5]

    Pitrou, Cyril and Coc, Alain and Uzan, Jean-Philippe and Vangioni, Elisabeth , title = ". Phys. Rep. , year = 2018, month = sep, volume =. doi:10.1016/j.physrep.2018.04.005 , archivePrefix =. 1801.08023 , primaryClass =

    work page doi:10.1016/j.physrep.2018.04.005 2018

  6. [6]

    and Olive, Keith A

    Fields, Brian D. and Olive, Keith A. and Yeh, Tsung-Han and Young, Charles , title = ". , year = 2020, month = mar, volume =. doi:10.1088/1475-7516/2020/03/010 , archivePrefix =. 1912.01132 , primaryClass =

    work page doi:10.1088/1475-7516/2020/03/010 2020

  7. [7]

    One percent determination of the primordial deuterium abundance

    Cooke, Ryan J. and Pettini, Max and Steidel, Charles C. , title = ". , year = 2018, month = mar, volume =. doi:10.3847/1538-4357/aaab53 , archivePrefix =. 1710.11129 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aaab53 2018

  8. [8]

    and Costero, R

    Peimbert, M. and Costero, R. , title = ". Boletin de los Observatorios Tonantzintla y Tacubaya , year = 1969, month = may, volume =

    1969

  9. [9]

    Pagel, B. E. J. and Simonson, E. A. and Terlevich, R. J. and Edmunds, M. G. , title = ". , year = 1992, month = mar, volume =. doi:10.1093/mnras/255.2.325 , adsurl =

    work page doi:10.1093/mnras/255.2.325 1992

  10. [10]

    Improving Predictions for Helium Emission Lines

    Benjamin, Robert A. and Skillman, Evan D. and Smits, Derck P. , title = ". , year = 1999, month = mar, volume =. doi:10.1086/306923 , archivePrefix =. astro-ph/9810087 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/306923 1999

  11. [11]

    Porter, R. L. and Ferland, G. J. and Storey, P. J. and Detisch, M. J. , title = ". , year = 2012, month = sep, volume =. doi:10.1111/j.1745-3933.2012.01300.x , archivePrefix =. 1206.4115 , primaryClass =

    work page doi:10.1111/j.1745-3933.2012.01300.x 2012

  12. [12]

    A Realistic Determination of the Error on the Primordial Helium Abundance: Steps Toward Non-Parametric Nebular Helium Abundances

    Olive, Keith A. and Skillman, Evan D. , title = ". , year = 2004, month = dec, volume =. doi:10.1086/425170 , archivePrefix =. astro-ph/0405588 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/425170 2004

  13. [13]

    Revised Primordial Helium Abundance Based on New Atomic Data

    Revised Primordial Helium Abundance Based on New Atomic Data. , year = 2007, month = sep, volume =. doi:10.1086/520571 , archivePrefix =. astro-ph/0701580 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/520571 2007

  14. [14]

    The primordial abundance of 4He: evidence for non-standard big bang nucleosynthesis

    The Primordial Abundance of ^ 4 He: Evidence for Non-Standard Big Bang Nucleosynthesis. , year = 2010, month = feb, volume =. doi:10.1088/2041-8205/710/1/L67 , archivePrefix =. 1001.4440 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/2041-8205/710/1/l67 2010

  15. [15]

    The effects of He I 10830 on helium abundance determinations

    The effects of He I 10830 on helium abundance determinations. , year = 2015, month = jul, volume =. doi:10.1088/1475-7516/2015/07/011 , archivePrefix =. 1503.08146 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/1475-7516/2015/07/011 2015

  16. [16]

    , title =

    Steigman, G. , title =. Advances in High Energy Physics , volume =

  17. [17]

    Ioannidis, J. P. A. , title =. PLoS Medicine , volume =

  18. [18]

    , title =

    Fanelli, D. , title =. Scientometrics , volume =

  19. [19]

    and Fischhoff, B

    Henrion, M. and Fischhoff, B. , title =. American Journal of Physics , volume =

  20. [20]

    A Distance Framework out to 100 Mpc

    Clustering of Local Group Distances: Publication Bias or Correlated Measurements? VII. A Distance Framework out to 100 Mpc. , year = 2020, month = may, volume =. doi:10.3847/1538-4365/ab8562 , archivePrefix =. 2004.00114 , primaryClass =

    work page doi:10.3847/1538-4365/ab8562 2020

  21. [21]

    Extending to Virgo Cluster Distances

    Clustering of Local Group Distances: Publication Bias or Correlated Measurements? VI. Extending to Virgo Cluster Distances. , year = 2020, month = jan, volume =. doi:10.3847/1538-4365/ab5711 , archivePrefix =. 1911.04312 , primaryClass =

    work page doi:10.3847/1538-4365/ab5711 2020

  22. [22]

    Clustering of Local Group distances: publication bias or correlated measurements? V. Galactic rotation constants

    Clustering of Local Group Distances: Publication Bias or Correlated Measurements? V. Galactic Rotation Constants. , year = 2017, month = oct, volume =. doi:10.3847/1538-4365/aa8b71 , archivePrefix =. 1709.02501 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4365/aa8b71 2017

  23. [23]

    Clustering of Local Group distances: publication bias or correlated measurements? IV. The Galactic Center

    Clustering of Local Group Distances: Publication Bias or Correlated Measurements? IV. The Galactic Center. , year = 2016, month = nov, volume =. doi:10.3847/0067-0049/227/1/5 , archivePrefix =. 1610.02457 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/0067-0049/227/1/5 2016

  24. [24]

    Clustering of Local Group distances: publication bias or correlated measurements? III. The Small Magellanic Cloud

    Clustering of Local Group Distances: Publication Bias or Correlated Measurements? III. The Small Magellanic Cloud. , year = 2015, month = jun, volume =. doi:10.1088/0004-6256/149/6/179 , archivePrefix =. 1504.00417 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-6256/149/6/179 2015

  25. [25]

    Clustering of Local Group distances: publication bias or correlated measurements? II. M31 and beyond

    Clustering of Local Group Distances: Publication Bias or Correlated Measurements? II. M31 and Beyond. , keywords =. doi:10.1088/0004-6256/148/1/17 , archivePrefix =. 1405.2124 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-6256/148/1/17

  26. [26]

    Clustering of Local Group distances: publication bias or correlated measurements? I. The Large Magellanic Cloud

    Clustering of Local Group Distances: Publication Bias or Correlated Measurements? I. The Large Magellanic Cloud. , keywords =. doi:10.1088/0004-6256/147/5/122 , archivePrefix =. 1403.3141 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-6256/147/5/122

  27. [27]

    Planck 2018 results. VI. Cosmological parameters. , keywords =. doi:10.1051/0004-6361/201833910 , archivePrefix =. 1807.06209 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201833910 2018

  28. [28]

    Planck 2015 results. XIII. Cosmological parameters. , keywords =. doi:10.1051/0004-6361/201525830 , archivePrefix =. 1502.01589 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201525830 2015

  29. [29]

    Cosmological parameters from CMB and other data: a Monte-Carlo approach

    Cosmological parameters from CMB and other data: A Monte Carlo approach. , keywords =. doi:10.1103/PhysRevD.66.103511 , archivePrefix =. astro-ph/0205436 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1103/physrevd.66.103511

  30. [30]

    Conservative Constraints on Early Cosmology: an illustration of the Monte Python cosmological parameter inference code

    Conservative constraints on early cosmology with MONTE PYTHON. , keywords =. doi:10.1088/1475-7516/2013/02/001 , archivePrefix =. 1210.7183 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/1475-7516/2013/02/001 2013

  31. [31]

    Corrigendum: Improved He~I Emissivities in the Case B Approximation

    Erratum: `Improved He I emissivities in the Case B approximation'. , keywords =. doi:10.1093/mnrasl/slt049 , archivePrefix =. 1303.5115 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnrasl/slt049

  32. [32]

    , keywords =

    Primordial ^ 4 He abundance: a determination based on the largest sample of H II regions with a methodology tested on model H II regions. , keywords =. doi:10.1051/0004-6361/201220782 , archivePrefix =. 1308.2100 , primaryClass =

    work page doi:10.1051/0004-6361/201220782

  33. [33]

    , keywords =

    A new determination of the primordial He abundance using the He I 10830 A emission line: cosmological implications. , keywords =. doi:10.1093/mnras/stu1771 , archivePrefix =. 1408.6953 , primaryClass =

    work page doi:10.1093/mnras/stu1771

  34. [34]

    EMPRESS. VIII. A New Determination of Primordial He Abundance with Extremely Metal-poor Galaxies: A Suggestion of the Lepton Asymmetry and Implications for the Hubble Tension. , keywords =. doi:10.3847/1538-4357/ac9ea1 , archivePrefix =. 2203.09617 , primaryClass =

    work page doi:10.3847/1538-4357/ac9ea1

  35. [35]

    , keywords =

    A comprehensive chemical abundance analysis of the extremely metal poor Leoncino Dwarf galaxy (AGC 198691). , keywords =. doi:10.1093/mnras/stab3226 , archivePrefix =. 2109.00178 , primaryClass =

    work page doi:10.1093/mnras/stab3226

  36. [36]

    Memorie della Societa Astronomica Italiana Supplementi , keywords =

    The primordial helium abundance: no problem. Memorie della Societa Astronomica Italiana Supplementi , keywords =

  37. [37]

    , keywords =

    A new determination of the primordial helium abundance using the analyses of H II region spectra from SDSS. , keywords =. doi:10.1093/mnras/stab215 , archivePrefix =. 2101.09127 , primaryClass =

    work page doi:10.1093/mnras/stab215

  38. [38]

    , keywords =

    Mass measurements of the components of MU Cas. , keywords =. doi:10.1086/113534 , adsurl =

    work page doi:10.1086/113534

  39. [39]

    Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data

    Five-Year Wilkinson Microwave Anisotropy Probe Observations: Likelihoods and Parameters from the WMAP Data. , keywords =. doi:10.1088/0067-0049/180/2/306 , archivePrefix =. 0803.0586 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0067-0049/180/2/306

  40. [40]

    , keywords =

    Blinding multiprobe cosmological experiments. , keywords =. doi:10.1093/mnras/staa965 , archivePrefix =. 1911.05929 , primaryClass =

    work page doi:10.1093/mnras/staa965 1911

  41. [41]

    , keywords =

    Dark energy survey year 3 results: likelihood-free, simulation-based wCDM inference with neural compression of weak-lensing map statistics. , keywords =. doi:10.1093/mnras/stae2629 , archivePrefix =. 2403.02314 , primaryClass =

    work page doi:10.1093/mnras/stae2629

  42. [42]

    Cosmology from Planck CMB Lensing and DESI DR1 Quasar Tomography

    Cosmology from Planck CMB lensing and DESI DR1 quasar tomography. , keywords =. doi:10.1088/1475-7516/2025/10/077 , archivePrefix =. 2506.22416 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/1475-7516/2025/10/077 2025

  43. [43]

    Primordial helium abundance determination using sulphur as metallicity tracer

    Primordial helium abundance determination using sulphur as metallicity tracer. , keywords =. doi:10.1093/mnras/sty1206 , archivePrefix =. 1804.10701 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/sty1206

  44. [44]

    Determination of the primordial helium abundance based on NGC 346 an HII region of the Small Magellanic Cloud

    Determination of the Primordial Helium Abundance Based on NGC 346, an H II Region of the Small Magellanic Cloud. , keywords =. doi:10.3847/1538-4357/ab14e4 , archivePrefix =. 1904.01594 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/ab14e4 1904

  45. [45]

    , keywords =

    The PHLEK Survey: A New Determination of the Primordial Helium Abundance. , keywords =. doi:10.3847/1538-4357/ab91af , archivePrefix =. 2005.12290 , primaryClass =

    work page doi:10.3847/1538-4357/ab91af 2005

  46. [46]

    , keywords =

    Improving helium abundance determinations with Leo P as a case study. , keywords =. doi:10.1088/1475-7516/2021/03/027 , archivePrefix =. 2010.04180 , primaryClass =

    work page doi:10.1088/1475-7516/2021/03/027 2021

  47. [47]

    , keywords =

    Chemical abundances in seven metal-poor H II regions and a determination of the primordial helium abundance. , keywords =. doi:10.1093/mnras/stab1543 , archivePrefix =. 2105.12260 , primaryClass =

    work page doi:10.1093/mnras/stab1543

  48. [48]

    Helium abundance estimates

    Chemical abundances in Seyfert galaxies - IX. Helium abundance estimates. , keywords =. doi:10.1093/mnras/stac1722 , archivePrefix =. 2206.09836 , primaryClass =

    work page doi:10.1093/mnras/stac1722

  49. [49]

    , keywords =

    The Primordial Abundance of ^ 4 He Revisited. , keywords =. doi:10.1086/305698 , adsurl =

    work page doi:10.1086/305698

  50. [50]

    Astrophys

    Mixing in the Sun and Neutrino Fluxes. Astrophys. Lett. , year = 1968, month = jan, volume =

    1968

  51. [51]

    , year = 1969, month = jun, volume =

    Determinations of Helium Abundance from Radiofrequency Recombination Lines. , year = 1969, month = jun, volume =. doi:10.1086/150022 , adsurl =

    work page doi:10.1086/150022 1969

  52. [52]

    , keywords =

    Chemical composition of H II regions in the Large Magellanic Cloud and its cosmological implications. , keywords =. doi:10.1086/153166 , adsurl =

    work page doi:10.1086/153166

  53. [53]

    Semiconvection in Halo Stars and the Primordial Helium Abundance

  54. [54]

    , keywords =

    Chemical composition of H II regions in the Small Magellanic Cloud and the pregalactic helium abundance. , keywords =. doi:10.1086/154114 , adsurl =

    work page doi:10.1086/154114

  55. [55]

    , keywords =

    Pregalactic helium abundance and abundance gradients across our Galaxy from planetary nebulae. , keywords =

  56. [56]

    , keywords =

    Chemical abundances of a new halo planetary nebula. , keywords =. doi:10.1086/155171 , adsurl =

    work page doi:10.1086/155171

  57. [57]

    , keywords =

    Galaxies with the spectra of giant H II regions. , keywords =. doi:10.1086/158205 , adsurl =

    work page doi:10.1086/158205

  58. [58]

    , keywords =

    Star formation and abundances in the nearby irregular galaxy VII ZW 403. , keywords =. doi:10.1086/158896 , adsurl =

    work page doi:10.1086/158896

  59. [59]

    , keywords =

    Data on an unusual Wolf-Rayet star in the nearby Galaxy IC 1613. , keywords =. doi:10.1086/131034 , adsurl =

    work page doi:10.1086/131034

  60. [60]

    Philosophical Transactions of the Royal Society of London Series A , keywords =

    Constraints on the Primordial Helium Abundance from the Optical Emission Spectra of Dwarf Galaxies. Philosophical Transactions of the Royal Society of London Series A , keywords =. doi:10.1098/rsta.1982.0098 , adsurl =

    work page doi:10.1098/rsta.1982.0098 1982

  61. [61]

    Primordial Helium , year = 1983, editor =

    Helium content in globular clusters - The R-method. Primordial Helium , year = 1983, editor =

    1983

  62. [62]

    , keywords =

    Spectrophotometry of 12 metal-poor galaxies : implications for the primordial helium abundance. , keywords =. doi:10.1086/161350 , adsurl =

    work page doi:10.1086/161350

  63. [63]

    , keywords =

    Primordial helium, spectrophotometric technique and I Zwicky 18. , keywords =. doi:10.1086/191044 , adsurl =

    work page doi:10.1086/191044

  64. [64]

    CCD photometry in globular clusters. I. The age of NGC 6752. , keywords =

  65. [65]

    , keywords =

    The primordial helium abundance determination from metal-poor galaxies. , keywords =. doi:10.1086/131856 , adsurl =

    work page doi:10.1086/131856

  66. [66]

    , keywords =

    Collisional Effects in the Helium Triplets, and the Primordial Helium Abundance. , keywords =. doi:10.1086/184783 , adsurl =

    work page doi:10.1086/184783

  67. [67]

    , keywords =

    Reassessing the primordial helium abundance : new observations of NGC4861 and CG 1116+51. , keywords =. doi:10.1086/164753 , adsurl =

    work page doi:10.1086/164753

  68. [68]

    , keywords =

    Some inferences on chemical evolution from a study of irregular and blue compact galaxies. , keywords =

  69. [69]

    CCD photometry in globular clusters. II. NGC 7492. , keywords =

  70. [70]

    , year = 1987, month = may, volume =

    In Search of Primordial Helium. , year = 1987, month = may, volume =

    1987

  71. [71]

    Collisional excitation effects on He I line intensities

    Chemical composition of Type I planetary nebulae. Collisional excitation effects on He I line intensities. , year = 1987, month = may, volume =

    1987

  72. [72]

    , keywords =

    High-Resolution Spectroscopy and Direct Imaging of the Dwarf Galaxy I ZW 18. , keywords =. doi:10.1086/115100 , adsurl =

    work page doi:10.1086/115100

  73. [73]

    , keywords =

    Helium in three H II galaxies and the primordial helium abundance. , keywords =

  74. [74]

    A., Ferland, G

    Physical Conditions in the Orion Nebula and an Assessment of Its Helium Abundance. , keywords =. doi:10.1086/170146 , adsurl =

    work page doi:10.1086/170146

  75. [75]

    NGC 6171

    CCD-photometry of galactic globular clusters - III. NGC 6171. , keywords =. doi:10.1093/mnras/252.3.357 , adsurl =

    work page doi:10.1093/mnras/252.3.357

  76. [76]

    , keywords =

    The metal-poor HII galaxy SBS 0335-052 and the primordial helium abundance. , keywords =

  77. [77]

    , keywords =

    A Measurement of the Primordial Helium Abundance Using MU Cassiopeiae. , keywords =. doi:10.1086/171415 , adsurl =

    work page doi:10.1086/171415

  78. [78]

    , keywords =

    The galactic globular cluster NGC 5897 and its population of blue stragglers. , keywords =. doi:10.1093/mnras/256.3.376 , adsurl =

    work page doi:10.1093/mnras/256.3.376

  79. [79]

    , keywords =

    On Determining the Primordial Helium Abundance from the Spectra of H II Galaxies. , keywords =. doi:10.1086/172049 , adsurl =

    work page doi:10.1086/172049

  80. [80]

    , keywords =

    Chemical Evolution of Irregular Galaxies and the Primordial 4He Abundance. , keywords =. doi:10.1086/172183 , adsurl =

    work page doi:10.1086/172183

Showing first 80 references.