Multiple Stellar Populations of Globular Clusters from Homogeneous Ca--CN--CH Photometry. V. $cn^\prime_{\rm JWL}$ as a Surrogate $cn_{\rm JWL}$ Index and NGC 6723

Jae-Woo Lee

REVIEW 4 major objections 6 minor 41 references

Multiple Stellar Populations of Globular Clusters from Homogeneous Ca--CN--CH Photometry. V. $cn^\prime_{\rm JWL}$ as a Surrogate $cn_{\rm JWL}$ Index and NGC 6723

T0 review · 4 major / 6 minor · reviewed 2026-08-14 · deepseek-v4-flash

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Pith's one-line read This paper introduces a surrogate CN photometric index, cn′JWL, and uses it to show that NGC 6723's two red-giant populations share the same radial distribution — overturning a claimed counterexample to globular-cluster…

desk verdict A useful photometric-tool paper whose refutation of Lim et al. on NGC 6723 is probably correct but statistically oversold. read the letter →

arxiv 1908.06670 v1 pith:F4OYKQC7 submitted 2019-08-19 astro-ph.GA astro-ph.SR

Jae-Woo Lee This is my paper · ORCID

classification astro-ph.GAastro-ph.SR

keywords Hertzsprung-RussellandC-Mdiagramsstars:abundancesevolutionPopulationIIglobularclusters:individual(NGC6723)multiplestellarpopulationsCNphotometryradialdistributions

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

Star clusters born in a single burst should show one stellar population, yet most globular clusters show two or more; the usual explanation is that later-generation stars formed from ejecta enriched in nitrogen and helium. This paper introduces a new photometric index, $cn'_{\rm JWL} = Ca_{\rm CTIO} - Ca_{\rm JWL}$, as a surrogate for the validated CN-band tracer $cn_{\rm JWL}$, and uses it to re-examine NGC 6723, which a 2016 study had put forward as a counterexample because its CN-weak giants appeared more centrally concentrated than its CN-strong giants. With the new index, the two red-giant populations in NGC 6723 have statistically identical cumulative radial distributions and a number ratio $n({\rm CN\text{-}w}):n({\rm CN\text{-}s}) = 35.5:64.5 \pm 2.8$. The paper concludes that the earlier counterexample was an artifact of a poor CN tracer, and that NGC 6723 behaves like normal globular clusters, with a slightly helium-enriched CN-strong population inferred from the red-giant-branch bump, $\Delta Y = 0.012 \pm 0.012$.

What carries the argument

The load-bearing instrument is the photometric index $cn'_{\rm JWL} = Ca_{\rm CTIO} - Ca_{\rm JWL}$. Because the CTIO calcium filter's passband has aged into a shape close to the custom JWL39 filter, this difference reproduces the information in $cn_{\rm JWL} = JWL39 - Ca_{\rm JWL}$, making accurate CN-band ($\lambda3883$) tagging possible without the custom filter. Its partner, $ch_{\rm JWL} = (JWL43 - b) - (b - y)$, measures the CH G band at $\lambda4250$, and the parallelized indices $\|cn_{\rm JWL}$ and $\|cn'_{\rm JWL}$ (sequences aligned to red and blue RGB fiducials) perform the actual population separation. Classification uses an expectation-maximization two-component Gaussian mixture, membership comes from Gaia DR2 proper motions, and completeness is estimated from artificial-star experiments. Synthetic spectra from ATLAS12/SYNTHE and MOOG are used to check whether abundance differences can account for the observed RGB and AGB colors.

What would settle it

Reclassify NGC 6723 giants using cn′JWL photometry but with membership and completeness from HST proper motions, which cover the cluster center where Gaia DR2 is incomplete; if the CN-w population then appears more centrally concentrated than CN-s, the paper's refutation of the earlier counterexample fails. A cheaper check is high-resolution spectroscopy of stars tagged CN-w in the inner region: if their measured CN strengths disagree with the photometric tags, cn′JWL is not a reliable population tracer.

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Extended reading notes

Core claim

On its own terms, the paper's central discovery is that the color difference $cn'_{\rm JWL} = Ca_{\rm CTIO} - Ca_{\rm JWL}$ is a reliable surrogate for the previously validated CN-band index $cn_{\rm JWL} = JWL39 - Ca_{\rm JWL}$, and that this index, combined with a new CH measure $ch_{\rm JWL} = (JWL43 - b) - (b - y)$, cleanly separates the multiple populations of NGC 6723. For Gaia DR2 proper-motion members, the two RGB populations are classified with an expectation-maximization two-component Gaussian mixture, giving $n({\rm CN\text{-}w}):n({\rm CN\text{-}s}) = 35.5:64.5 \pm 2.8$; their cumulative radial distributions are statistically indistinguishable. That result contradicts the earlier claim of a centrally concentrated CN-w population, which the paper traces to misclassification by the $hk_{\rm CTIO}$ index, a poor CN tracer with weak CH contamination. The same data show discrete double AGB sequences, a CN-s RGB bump brighter by $0.031 \pm 0.030$ mag (translating to $\Delta Y = 0.012 \pm 0.012$), and a step-like photometric CN--CH anticorrelation in M5. Synthetic spectra reproduce the RGB sequences but not the CN-w AGB, suggesting a mild nitrogen enhancement or a large drop in $^{12}$C/$^{13}$C in those AGB stars.

Load-bearing premise

The load-bearing premise is that Gaia DR2 proper-motion membership and the artificial-star completeness corrections do not remove CN-w and CN-s stars at different rates as a function of radius; if the cluster center is incomplete in a population-dependent way, the observed identical radial distributions could be a sample artifact rather than a property of the cluster.

Editorial extensions

If this is right

The NGC 6723 reversed radial distribution claimed in the 2016 study disappears when stars are tagged with a clean CN index, so this cluster no longer counts as an observational counterexample to standard multiple-population formation.
The measured RGB ratio of 35.5:64.5 agrees with the independent HST-based first-generation fraction of 0.363 ± 0.017, supporting a flat population ratio that does not change with radius.
The CN-s RGB bump is brighter by 0.031 ± 0.030 mag, implying a modest helium enhancement of ΔY = 0.012 ± 0.012 for the later generation.
The cnJWL and cn′JWL CMDs reveal discrete double AGB populations, and the bright AGB number ratio is marginally consistent with the RGB ratio; the deficit of faint CN-s AGB stars suggests helium-enhanced stars may evolve as AGB-manqué.
Because cn′JWL requires only the existing CTIO calcium filter, archival photometry of other globular clusters can be re-analyzed with the same population-tagging procedure.

Reading between the lines

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

If the surrogate index passes independent validation, archival CaCTIO photometry of many clusters could be re-processed in the same way, turning claimed radial-segregation anomalies into a systematic survey without new observations.
The step-like photometric CN–CH relation in M5 suggests that the continuous abundance spreads reported in high-resolution Na–O studies may partly reflect measurement scatter; a joint photometric–spectroscopic analysis could test whether the underlying populations are genuinely discrete.
The RGB/AGB mismatch in synthetic colors points to phase-dependent abundance changes in first-generation stars that can be tested directly with high-resolution spectra of a handful of CN-w AGB stars in NGC 6723.
A center-complete reobservation with HST proper motions would decide whether Gaia DR2 incompleteness hid a real gradient; if the null result survives, other radial-segregation claims should be rechecked with the same index.

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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Worth a careful read, but the headline result is stronger than the statistics actually support. The central claim—that the two RGB populations in NGC 6723 have the same radial distribution—is credible and independently supported by Milone et al.'s HST number ratio, but the refutation of Lim et al. rests on the author's own reduction plus a Monte Carlo that returns P=4.5% for Lim's p-value under the null, not the 0.2% you'd expect from a well-calibrated test. "Highly improbable" is an overstatement.

What's genuinely new and good: the cn'JWL index as a cheap surrogate for cnJWL, the chJWL index for the CH G band, and the photometric CN-CH step function in M5. These are useful additions to the population-tagging toolkit. The paper also does a real service by showing that hkCTIO—the exact index Lim used—is a poor CN tracer with continuous population transitions, which plausibly explains the earlier result. The synthetic RGB models match observations well, and the AGB discrepancy discussion is honest about adopting CNO abundances from M5 rather than measuring them.

Soft spots, in proportion: (1) The actual KS p-values for the flat radial distributions are never reported, so "most likely drawn from same parent" is unquantified. (2) The Table 4 calibration problem is real; the author includes a better-calibrated "Empirical1" row (0.18%) but does not explain why the main empirical row gives 4.46%. (3) The completeness correction is openly described as not exactly correct and "delicate," yet it is applied after the fact to both populations jointly; differential incompleteness by population and radius would not be captured. (4) The bright AGB number-ratio agreement uses a magnitude cut chosen after the full AGB sample disagreed. (5) No data or code, which limits independent reproducibility.

This is a paper for people working directly on globular cluster multiple populations, especially on photometric indices. It deserves peer review—the observations, external spectroscopic calibration, and the direct comparison to Lim's index make it legitimate—but a referee should ask for quantified KS results, a properly calibrated null, and more cautious wording in the abstract and summary.

Referee Report

4 major / 6 minor

Summary. This paper, the fifth in the author's series on homogeneous Ca-CN-CH photometry, introduces two new photometric indices, cn'_JWL = Ca_CTIO - Ca_JWL and ch_JWL = (JWL43 - b) - (b - y), intended as accurate measures of the CN lambda 3883 band and the CH G band. Using M5 RGB stars, the author shows that ||cn'_JWL correlates well with ||cn_JWL (rho = 0.918) and that the photometric CN-CH relation between the CN-w and CN-s populations is step-like rather than continuous. Applying the indices to NGC 6723, the paper reports an RGB number ratio n(CN-w):n(CN-s) = 35.5:64.5 +/- 2.8, no radial gradient between the two RGB populations (contradicting Lim et al. 2016), Delta Y = 0.012 +/- 0.012 for the CN-s population from the RGB bump, and discrete double AGB populations whose bright-star ratio is marginally consistent with the RGB ratio. Synthetic spectra reproduce the RGB sequences but leave a 0.035 mag discrepancy for the CN-w AGB, which is attributed to a possible mild nitrogen enhancement and/or a large 12C/13C decrement.

Significance. If the no-radial-gradient result holds, the paper removes an important claimed counterexample to the standard formation scenario for globular-cluster multiple populations and demonstrates that a ground-based Ca-CN-CH system can tag populations reliably. The paper's strengths include agreement of the RGB ratio with the independent HST measurement of Milone et al. (2017), consistency with the Milone et al. (2018) helium estimate, and an explicit, transparent discussion of the limitations of the completeness correction and of the adopted CNO abundances. The central refutation of Lim et al. (2016), however, rests on a Monte Carlo calibration that is internally inconsistent and on a completeness treatment that is not population-specific, so the quantitative support for the headline claim is currently weaker than the text states.

major comments (4)

[Section 6.3.2, Table 4] The calibration of the Monte Carlo test is internally inconsistent. Under the null hypothesis, a two-sample K-S p-value is uniform on [0,1], so P(p <= 0.002) should be 0.2%. The 'Empirical' entry of 4.46% is more than twenty times larger, while 'Empirical1' and 'Gaussian' give 0.18% and 0.20%. This indicates that the empirical simulation does not sample a correctly pooled null distribution, so the statement in Section 7 that Lim et al.'s result has less than 5% probability and is 'highly improbable' is not supported by the reported numbers. Please report the actual K-S statistics and p-values for the comparisons in Figure 13 and rerun the randomization under a properly defined null hypothesis.
[Section 6.3.2, Figure 13] The text states that K-S tests show the CN-w and CN-s populations are most likely drawn from the same parent distribution, but no test statistic or p-value is reported for any of the three color indices. The reader cannot distinguish p approximately 0.04 from p approximately 0.4, which matters because the paper's central claim is the absence of radial segregation. Please tabulate D and p for ||cn_JWL, ||cn'_JWL, and ||hk_CTIO, together with sample sizes and the radial ranges used.
[Sections 6.1 and 6.3.2] The completeness correction used to argue that incomplete detection cannot hide a radial gradient is not population-specific. The artificial-star completeness fractions f_complete are computed for the full sample, while the relevant question is whether CN-w and CN-s stars are detected and retained at different rates as a function of radius in this bulge-contaminated field (l = 0.07 deg, b = -17.30 deg) with Gaia DR2 proper-motion membership incomplete in the center. The paper itself notes that applying f_complete to the observed radial distributions is not exactly correct and that the inverse process is delicate. Please test the pipeline's ability to recover an artificially injected reversed gradient of the kind claimed by Lim et al. (2016), or provide per-population completeness and membership-retention curves with radial uncertainties.
[Section 6.4.1, Figure 16] The inferred need for extra nitrogen enhancement and/or a large 12C/13C decrement in the CN-w AGB is conditional on adopting the CNO abundances of M5 for NGC 6723 and on the specific ATLAS12/SYNTHE model assumptions. Since no CNO abundances for NGC 6723 are available, the 0.035 mag discrepancy could instead reflect incorrect input abundances, model atmospheres, or the adopted isochrones. The abstract states this as a result; please either soften the claim to a model-dependent speculation or obtain spectroscopic CNO constraints for at least a few NGC 6723 giants.

minor comments (6)

[Section 1] The phrase 'one of the most greatest achievements' contains a grammatical error; it should be 'one of the greatest achievements'.
[Figure 14 caption] The fourth panel is labeled '(c)' twice; the label for the final panel should be '(d)'.
[Figure 14 caption] 'Mote Carlo simulations' should be 'Monte Carlo simulations'.
[Section 4] 'the second Gaia date release' should be 'the second Gaia data release'.
[Section 6.4.1] The text adopts [Fe/H] approximately -1.0 dex but the footnote gives [Fe/H] = -0.93 +/- 0.05 from Crestani et al. (2019); please state explicitly which value is used in the synthetic models and whether the difference affects the conclusions.
[References] The in-text citation 'Zachairias et al. (2004)' is misspelled; it should be 'Zacharias et al. (2004)' to match the reference list.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity found; the index validation rests on external spectroscopic benchmarks and the central radial-distribution claim is data-driven rather than definitional.

full rationale

The paper's derivation chain is not circular. The new cn'JWL index is introduced as an empirical surrogate for cnJWL, and the correlation between them (Table 1, rho = 0.918) is a validation, not a derivation of a predicted quantity from the same input. The underlying cnJWL index is independently anchored to the external spectroscopic delta-S(3839) index of Smolinski et al. (2011) with rho = 0.981, and chJWL is compared with the external CH(4300) index. The RGB population ratio in NGC 6723, n(CN-w):n(CN-s) = 35.5:64.5 +/- 2.8, is checked against the independent HST measurement of Milone et al. (2017), who found an FG fraction of 0.363 +/- 0.017. The helium enhancement estimate is derived from the standard RGB-bump luminosity method and agrees with an external HST result. The synthetic spectra for the AGB discrepancy use ATLAS12, SYNTHE, MOOG, Dartmouth isochrones, and abundances adopted from Cohen et al. (2002); they are not fitted to the CN-w AGB discrepancy but are used to propose falsifiable abundance variations. The central claim of identical cumulative radial distributions for the two populations is an empirical result from Gaia DR2 membership and the paper's photometry, not a consequence of how the indices are defined. Concerns about Gaia completeness in the cluster center, the approximate inverse completeness correction, and the Monte Carlo result P = 4.46% in Table 4 are statistical and observational robustness issues rather than circular reductions; the paper even states that its completeness correction is not exactly correct. Self-citations to earlier Lee papers are present, but the load-bearing calibrations and comparisons are external, so no circular step is established by the quoted equations or construction.

Assumptions & free parameters 5 free parameters · 5 assumptions · 0 invented entities

The central claims rest on the calibration of the author's filter system, the EM population model, adopted abundances from M5, and the Gaia completeness treatment. Several numerical inputs, including CNO abundances for NGC 6723 and the proposed AGB abundance changes, are adopted without independent measurement, which raises the burden on the synthetic model comparison.

free parameters (5)

Adopted CNO abundances for NGC 6723 populations (from M5) = [C/Fe]=-0.2, [N/Fe]=-0.1, [O/Fe]=+0.3 (CN-w); [C/Fe]=-0.8, [N/Fe]=+1.3, [O/Fe]=-0.2 (CN-s)
Section 6.4.1 states these abundances for NGC 6723 are not known and are simply adopted from M5 (Cohen et al. 2002). The synthetic cnJWL fiducials and the claimed CN-w AGB discrepancy depend on these values.
Nitrogen enhancement for CN-w AGB = Delta[N/Fe] = 0.1 dex
Section 6.4.1 introduces this value to make the synthetic CN-w AGB sequence redder and match the photometry.
Carbon isotope ratio for CN-w AGB = 12C/13C approximately 2.3 (from initial approximately 20)
Section 6.4.1 proposes a large decrement in 12C/13C to explain the CN-w AGB discrepancy.
Gaussian mixture model parameters for population classification = Means, variances, and mixing fraction fitted by EM
Sections 4 and 6.3 use a two-component Gaussian mixture fitted to the parallelized color indices to classify stars. The resulting number ratios depend on this fitted model.
Parallelization fiducial sequences (CIred, CIblue) = Not tabulated, defined per cluster by eye or fit
Equation (8) uses red and blue fiducial sequences; the paper does not specify how these are determined, so they are effectively free inputs.

assumptions (5)

domain assumption CN band at lambda 3883 is primarily a nitrogen tracer and CH G band at lambda 4250 a carbon tracer in cool giants.
Underlies the interpretation of cnJWL, cn'JWL, and chJWL throughout, e.g., Section 4 discusses the CN-CH anticorrelation.
domain assumption Two-component Gaussian mixture correctly describes the population distribution in the parallelized indices.
The EM classification in Sections 4 and 6.3 assumes exactly two populations with Gaussian color distributions; a non-bimodal or skewed distribution would bias the derived ratios.
domain assumption The RGB bump luminosity difference between populations is caused only by helium, with no age or metallicity differences.
Section 6.3.1 states: 'If there exist no differences in metallicity and age between the two RGB populations, the difference in the RGBB magnitude can translate into the difference in the mean helium abundance.' This converts the measured bump shift into Delta Y.
domain assumption ATLAS12, SYNTHE, MOOG, and Dartmouth isochrones accurately model the relevant stellar atmospheres and evolution for RGB and AGB stars.
Section 6.4.1 uses these tools to compute synthetic cnJWL; any systematic errors in line lists or model atmospheres would change the predicted fiducials and the inferred AGB abundance anomaly.
domain assumption Gaia DR2 proper-motion membership and completeness corrections are adequate for the radial distribution comparison.
Section 6.1 uses Gaia DR2 to select members and Section 6.3.2 applies completeness fractions; the no-radial-gradient conclusion assumes these do not introduce a population-dependent radial bias.

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Cite this review

Pith. "Pith review of Multiple Stellar Populations of Globular Clusters from Homogeneous Ca--CN--CH Photometry. V. $cn^\prime_{\rm JWL}$ as a Surrogate $cn_{\rm JWL}$ Index and NGC 6723." pith.science (2026). https://pith.science/paper/F4OYKQC7

@misc{pith2026190806670,
  author       = {Pith},
  title        = {Pith review of: Multiple Stellar Populations of Globular Clusters from Homogeneous Ca--CN--CH Photometry. V. $cn^\prime_\rm JWL$ as a Surrogate $cn_\rm JWL$ Index and NGC 6723},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/F4OYKQC7}},
  note         = {Machine review of arXiv:1908.06670}
}

abstract

We introduce new color indices $cn^\prime_{\rm JWL}$ (= $Ca_{\rm CTIO} - Ca_{\rm JWL}$) and $ch_{\rm JWL}$ [=$(JWL43 - b) - (b-y)$], accurate photometric measures of the CN band at $\lambda$3883 and the CH G band, respectively, in the study of the multiple populations (MPs) in globular clusters (GCs). Our photometric CN--CH relation for a large number of red-giant branch (RGB) in M5 shows that the evolutions of the CN and CH between the CN-w and CN-s populations are not continuous. Armed with our new color indices, we investigate the MPs of NGC 6723, finding the RGB populational number ratio of $n$(CN-w):$n$(CN-s) $\approx$ 35.5:64.5 ($\pm$2.8) with no radial gradient. Similar to other normal GCs with MPs, the helium abundance of the CN-s population inferred from the RGB bump magnitude is slightly enhanced by $\Delta Y$ = 0.012 $\pm$ 0.012. Our $cn_{\rm JWL}$ and $cn^\prime_{\rm JWL}$ color-magnitude diagrams clearly show the discrete double AGB populations in NGC 6723, whose bright AGB populational number ratio is in marginally agreement with that of the RGB stars within the statistical errors. Finally, our synthetic $cn_{\rm JWL}$ index is in good agreement with observations, except for the CN-w asymptotic giant branch (AGB). To mitigate the discrepancy in the CN-w AGB may require a mild nitrogen enhancement and/or a large decrement in the $^{12}$C/$^{13}$C ratio with respect to the bright RGB.

Figures

Figures reproduced from arXiv: 1908.06670 by the authors.

**Figure 3.** Comparisons of synthetic spectra of the FG (the blue solid line) and the SG (the red solid line) around the CH G band. The continuum sidebands defined by S.-G. Lee (1999) are shown with gray shaded boxes, showing that these continuum sidebands are severely contaminated by the CH molecular band. The transmission function of our JW L43 filter is also shown with the dark green solid line [PITH_FULL_IMAGE:figures/full… view at source ↗

**Figure 5.** CMDs for the proper motion membership M5 RGB stars with −2 mag ≤ V −VHB ≤ 2 mag and σ(cnJWL) ≤ 0.005 mag. The blue dots denote the CN-w population and the red dots the CN-s population based on the cnJWL,cor distribution in [PITH_FULL_IMAGE:figures/full_fig_p004_5.png] view at source ↗

Figures from the paper (8 more)

**Figure 6.** Figure 6: Parallelized CMDs for the proper motion membership M5 RGB stars with −0.5 ≤ V −VHB ≤ 2.0 mag and σ(cnJWL) ≤ 0.005 mag. The blue dots denote the CN-w population and the red dots the CN-s population based on the cnJWL,cor distribution in Figure 4. The kcnJWL and the k∆C…

**Figure 7.** Figure 7: Plots of δS(3839) versus parallelized cnJWL and hk′ JWL for M3 RGB stars along with least-square fits. The mean residuals (±1σ) around the fitted lines are also shown with long-dashed lines. The khk′ JWL index shows a weak correlation, with the correlation coefficient…

**Figure 9.** Figure 9: Comparisons of color indices of the proper motion membership M5 RGB stars with −0.5 ≤ V −VHB ≤ 2.0 mag and σ(cnJWL) ≤ 0.005 mag. Our kcnJWL is nicely correlated with the kcn′ JWL and is inversely correlated with our kchJWL, a photometric analogue of the CN–CH anticorr…

**Figure 10.** Figure 10: (a)–(d) CMDs of the NGC 6723 membership stars based on the proper motion study of the second Gaia data release. (e)–(h) CMDs of the off-cluster stars toward NGC 6723 field. We show selected CMDs for NGC 6723 in [PITH_FULL_IMAGE:figures/full_fig_p008_10.png]

**Figure 11.** Figure 11: Parallelized CMDs and distributions for NGC 6723 RGB stars. The discrete double RGB sequences can be clearly seen in the kcnJWL and the kcn′ JWL indices, while rather continuous transitions from one population to the other in the khkCTIO and the khk′ JWL indices. In …

**Figure 13.** Figure 13: (a) A comparison of the cumulative radial distributions of the CN-w (blue) and the CN-s (red) RGB stars classified from the kcnJWL index in NGC 6723. The blue and the red horizontal lines denote the mean fractions for each population with ±1σ. (b) Same as (a), but fro…

**Figure 15.** Figure 15: CMDs of bright stars in NGC 6723. Black dots, green circles, red plus signs, blue crosses, and cyan circles denote the RGB, AGB, red HB (RHB), BHB, and RRL, respectively, where the photometry for the RRL variables is not phase-averaged. The hkCTIO CMD shows that the h…

**Figure 16.** Figure 16: The CMD of RGB stars with −2 mag ≤ V −VHB ≤ 2 mag, and AGB stars in NGC 6723. The CN-w and the CN-s RGB stars are denoted with blue crosses and red plus signs, while the CN-w and the CN-s AGB stars with green circles and magenta diamonds. We also show synthetic cnJWL…

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Works this paper leans on

41 extracted references · 36 canonical work pages

[1]

J., Laird, J

Anthony-Twarog, B. J., Laird, J. N., Payne, D., & Twarog, B. A . 1991, AJ, 101, 1902

work page 1991
[2]

2019, MNRA S, 480, 3739

Bastian, N., Kamann, S., Cabrera-Ziri, I., et al. 2019, MNRA S, 480, 3739

work page 2019
[3]

2019, MNRAS, 482, 5138

Baumgardt, H., Hilker, M., Sollima, A., & Bellini, A. 2019, MNRAS, 482, 5138

2019
[4]

2010, ApJL, 723, L99

Bekki, K. 2010, ApJL, 723, L99

work page 2010
[5]

M., Smith, G

Briley, M. M., Smith, G. H., Bell, R. A., Oke, J. B., & Hesser, J . E. 1992, ApJ, 387, 612

work page 1992
[6]

Brown, A.G.A., V allenari, A., Prusti, T. et al. 2018, A&A, 616, A1

work page 2018
[7]

W., D’Orazi, V ., Y ong, D

Campbell, S. W., D’Orazi, V ., Y ong, D. et al. 2013, Nature, 498, 198

work page 2013
[8]

2014, ApJL, 795, L28 Carretta E., Bragaglia, A., Gratton, R.G., Lucatello S., Ca ntanzaro G

Carretta, E. 2014, ApJL, 795, L28 Carretta E., Bragaglia, A., Gratton, R.G., Lucatello S., Ca ntanzaro G. et al. 2009, A&A, 505, 117

work page 2014

Show all 41 references

[9]

2013, Old Stellar Populations: ho w to study the fossil record of galaxy formation (Berlin:Wiley- VCH)

Cassisi, S., & Salaris, M. 2013, Old Stellar Populations: ho w to study the fossil record of galaxy formation (Berlin:Wiley- VCH)

2013
[10]

2005, Mem

Castelli, F. 2005, Mem. S.A.It. Suppl. 8, 25

2005
[11]

G., Briley, M

Cohen, J. G., Briley, M. M., Stetson, P . B. 2002, AJ, 123, 2525

2002
[12]

Crestani, J., Alves-Brito, A., Bono, G. et al. 2019, MNRAS, 4 87, 5463

2019
[13]

Dotter, A., Chaboyer, B., Jevremovi ´c, D. et al. 2008, ApJS, 178, 89

2008
[14]

K., & Avrett, E

Dupree, A. K., & Avrett, E. H. 2013, ApJL, 773, L28

2013
[15]

R., Lucatello, S., Sollima A

Gratton, G. R., Lucatello, S., Sollima A. et al. 2015, A&A, 57 3, A92 cnJWL VERSUS cn′ JWL 15

2015
[16]

Andersen, M. I. 1999, ApJ, 524, 242

1999
[17]

Harris, W. E. 1996, AJ, 112, 1487

1996
[18]

I., Kraft, R

Ivans, I. I., Kraft, R. P ., Sneden, C. et al. 2001, AJ, 122, 143 8

2001
[19]

1970, SAOSR, 309, 291

Kurucz, R., L. 1970, SAOSR, 309, 291

1970
[20]

2005, Mem

Kurucz, R., L. 2005, Mem. S.A.It. Suppl. 8, 14

2005
[21]

P ., Milone, A

Lagioia, E. P ., Milone, A. P ., Marino, A. F., et al. 2018, MNRAS, 475, 4088

2018
[22]

2010, MNRAS, 405, L36

Lee, J.-W. 2010, MNRAS, 405, L36

2010
[23]

2016, ApJS, 226, 16

Lee, J.-W. 2016, ApJS, 226, 16

2016
[24]

2018, ApJS, 238, 24

Lee, J.-W. 2018, ApJS, 238, 24

2018
[25]

Lee, J.-W., & Carney, B. W. 1999, AJ, 117, 2868

1999
[26]

Lee, J.-W., López-Morales, M., Hong, K. et al. 2014, ApJS, 21 0, 6

2014
[27]

2016, JKAS, 49, 289

Lee, J.-W., & Pogge, R. 2016, JKAS, 49, 289

2016
[28]

Lim, D., Lee, Y .-W., Pasquato, M. et al. 2016, ApJ, 832, 99

2016
[29]

F., Milone, A

Marino, A. F., Milone, A. P ., Casagrande, L., et al. 2018, ApJ L, 863, L33

2018
[30]

F., Milone, A

Marino, A. F., Milone, A. P ., Y ong, D., et al. 2017, ApJ, 843, 66

2017
[31]

F., Villanova, S., Piotto, G

Marino, A. F., Villanova, S., Piotto, G. et al. 2008, AAS Meet ing Abstracts, 490, 625

2008
[32]

P ., Marino., A

Milone, A. P ., Marino., A. F., Mastrobuono-Battisti, A., & Lagioia, E. P . 2018, MNRAS, 479, 5005

2018
[33]

P ., Marino, A

Milone, A. P ., Marino, A. F., Piotto, G. et al. 2015, ApJ, 808, 51

2015
[34]

P ., Piotto, G., Renzini, A

Milone, A. P ., Piotto, G., Renzini, A. et al. 2017, MNRAS, 464 , 3636

2017
[35]

L., Freeman, K

Norris, J., Cottrell, P . L., Freeman, K. C., & Da Costa, G. S. 1 981, ApJ, 244, 205 Piotto. G., Milone, A. P ., Bedin, L. R. et al. 2015, AJ, 149, 91

2015
[36]

Sbordone, L., Bonifacio, P ., Castelli, F., & Kurucz, R. L. 2004, Mem. S.A.It. Suppl. 5, 93

2004
[37]

Smith, G. H. 1987, PASP, 99, 67

1987
[38]

P ., Martell, S., Beers, T

Smolinski, J. P ., Martell, S., Beers, T. C., et al. 2011, ApJ, 142, 126

2011
[39]

1973, ApJ, 184, 839

Sneden, C. 1973, ApJ, 184, 839

1973
[40]

I., & Kraft, R

Sneden, C., Ivans, I. I., & Kraft, R. P . 2000, Mem. Soc. Astron. Italiana, 71, 657 Stetson P . B. 1987, PASP, 99, 191 Stetson P . B. 1994, PASP, 106, 250 Stetson P . B., & Harris, W. E. 1988, AJ, 96, 909

2000
[41]

G., Levine, S

Zacharias, N., Monet, D. G., Levine, S. E., et al. 2004, AAS, 2 05, 4815

2004

Pith tools

Reviewed August 14, 2026 · model on record in the stance chip above.

[1] [1]

J., Laird, J

Anthony-Twarog, B. J., Laird, J. N., Payne, D., & Twarog, B. A . 1991, AJ, 101, 1902

work page 1991

[2] [2]

2019, MNRA S, 480, 3739

Bastian, N., Kamann, S., Cabrera-Ziri, I., et al. 2019, MNRA S, 480, 3739

work page 2019

[3] [3]

2019, MNRAS, 482, 5138

Baumgardt, H., Hilker, M., Sollima, A., & Bellini, A. 2019, MNRAS, 482, 5138

2019

[4] [4]

2010, ApJL, 723, L99

Bekki, K. 2010, ApJL, 723, L99

work page 2010

[5] [5]

M., Smith, G

Briley, M. M., Smith, G. H., Bell, R. A., Oke, J. B., & Hesser, J . E. 1992, ApJ, 387, 612

work page 1992

[6] [6]

Brown, A.G.A., V allenari, A., Prusti, T. et al. 2018, A&A, 616, A1

work page 2018

[7] [7]

W., D’Orazi, V ., Y ong, D

Campbell, S. W., D’Orazi, V ., Y ong, D. et al. 2013, Nature, 498, 198

work page 2013

[8] [8]

2014, ApJL, 795, L28 Carretta E., Bragaglia, A., Gratton, R.G., Lucatello S., Ca ntanzaro G

Carretta, E. 2014, ApJL, 795, L28 Carretta E., Bragaglia, A., Gratton, R.G., Lucatello S., Ca ntanzaro G. et al. 2009, A&A, 505, 117

work page 2014