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REVIEW 4 major objections 4 minor 91 references

FEAST: JWST/NIRCam view of the Resolved Stellar Populations of the Interacting Dwarf Galaxies NGC~4485/NGC~4490

T0 review · 4 major / 4 minor · reviewed 2026-08-05 · deepseek-v4-flash

Pith's one-line read JWST images of NGC 4485/4490 reveal two recent starbursts, at roughly 30 and 100–200 Myr old, joined by a young-star bridge with a metal gradient, pointing to a close pass that stripped gas from NGC 4485 and fueled NGC 4490.

desk verdict First NIRCam resolved census of Arp 269 with careful data and public products, but the metallicity gradient and burst ages are partly built on the same assumed [Fe/H] inputs. read the letter →

arxiv 2509.01740 v1 pith:NIKHMFEG submitted 2025-09-01 astro-ph.GA

classification astro-ph.GA
keywords dwarfgalaxiesgalaxyinteractionsresolvedstellarpopulationsJWST/NIRCamcolor-magnitudediagramsstarformationhistorytidalbridgemetallicitygradient
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

The paper uses JWST/NIRCam images in two near-infrared filters to resolve individual stars in NGC 4485/NGC 4490, the closest known interacting pair of late-type dwarf galaxies outside the Magellanic Clouds. From the color-magnitude diagrams it reads the pair's recent star formation history: a burst beginning about 30 Myr ago appears as a gap-and-bright-sequence pattern in red supergiant stars, and an older burst about 100–200 Myr ago appears as an overdensity of blue core helium-burning stars concentrated in NGC 4485. The older burst lines up with the most recent pericenter passage predicted by existing N-body simulations, and young stars trace a tidal bridge connecting the two galaxies. The paper also measures a roughly 0.2 magnitude shift in the red supergiant sequences across the bridge, which it interprets as a factor-of-two difference in metal content, and argues that the last encounter stripped metal-poor gas from NGC 4485, which was then accreted, mixed, and fueled star formation in NGC 4490 and the bridge. If correct, this makes the pair a nearby testbed for how dwarf-dwarf interactions drive bursts and chemical enrichment.

What carries the argument

The central objects are the NIRCam color-magnitude diagrams in F115W/F200W, interpreted with PARSEC-COLIBRI stellar isochrones. Three features carry the argument: the red supergiant (RSG) sequence, where a gap marks a lull in star formation followed by a burst about 5–30 Myr ago; the blue core helium-burning (blue loop) overdensity, which dates the older burst to 100–200 Myr; and the median-color shift of RSG sequences, used as a metallicity indicator across the bridge. Spatial maps of age-selected stars trace the bridge, the dust lane, and the spatial coherence of the bursts.

What would settle it

A spatially resolved abundance measurement along the bridge, for example spectroscopy of H II regions or hot blue supergiants in the two bridge tiles, that showed the two young populations have the same oxygen abundance would disprove the metallicity-gradient interpretation; the roughly 0.2 magnitude red supergiant shift would then have to come from grey dust or reddening, and the gas-stripping scenario would lose its resolved-stellar support.

Watch

Extended reading notes

Core claim

Using NIRCam F115W and F200W photometry of the Arp 269 pair, the paper resolves individual stars and reads the near-infrared color-magnitude diagrams as a fossil record of the interaction. The CMDs show a burst starting about 30 Myr ago, visible as a gap in the red supergiant sequence followed by a populated bright section, and an earlier, precisely dated burst 100–200 Myr ago, visible as an overdensity of blue core helium-burning stars in NGC 4485. The older burst matches the ~230 Myr ago pericenter passage predicted by N-body simulations. Young stars form a bridge extending from NGC 4485 to NGC 4490, and the median color of the red supergiant sequence shifts by about 0.2 magnitudes between

Load-bearing premise

The load-bearing premise is that the young stellar populations of the two galaxies genuinely differ in metal content rather than in dust, because the paper chooses different metal abundances for the two galaxies to fit the red supergiant colors, then reads the measured color shift as confirming that metal gradient.

Editorial extensions

If this is right

  • The ~30 Myr starburst is synchronized across the bridge and part of NGC 4490's northeast disk, implying the interaction triggered star formation on roughly 2 kpc scales at nearly the same time.
  • The age-dated 100–200 Myr burst in NGC 4485's core independently supports a recent close passage, tightening the interaction timeline against the N-body prediction of ~230 Myr ago.
  • If the metal gradient holds, the gas that fueled the bridge was stripped from the lower-mass, more metal-poor galaxy, meaning dwarf-dwarf encounters can chemically pre-enrich the interstellar medium of a more massive companion.
  • Reddened old RGB stars along the bridge trace a continuous gas and dust lane that currently coincides with HI, connecting the galaxies and sustaining the active star-forming regions.

Reading between the lines

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

  • Beyond the paper: a full time-resolved star formation history fit to these CMDs, which the authors say is in preparation, would test whether the two-burst structure survives and would let the recovered burst times be compared directly with the simulated encounter timeline.
  • Beyond the paper: if the gas-stripping picture is right, this pair acts as an isolated control experiment for how dwarf-dwarf tides alone strip and mix gas, without a Milky-Way-like primary; the fast HI tail kinematics could be compared with the stellar bridge ages to test the stripping mechanism.
  • Beyond the paper: the reddened RGB stars suggest old stellar populations are embedded in the same gas and dust lane as young stars, so deep wide-field imaging outside the current footprint could reveal whether the old halos are truly unperturbed or simply beyond the field of view.
  • Beyond the paper: applying the same F115W/F200W CMD analysis to other dwarf pairs in the same observing program would show whether such synchronized post-pericenter bursts are a common outcome of dwarf-dwarf encounters.
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Editorial analysis

A structured set of objections, weighed in public.

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

Referee Report

4 major / 4 minor

Summary. This paper presents JWST/NIRCam F115W/F200W resolved stellar photometry of the interacting dwarf pair NGC 4485/NGC 4490 (Arp 269). The authors reduce the data with DOLPHOT on 18 tiles, inject 18 million artificial stars to characterize completeness and errors, and compare the resulting CMDs with PARSEC-COLIBRI isochrones. On this basis they report a young bridge connecting the two galaxies, two distinct bursts of star formation at ~30 Myr and ~100–200 Myr, a spatial concentration of 100–200 Myr stars in the center of NGC 4485, and a ~0.2 mag color shift of the red supergiant sequences between tile 5 and tile 9 that they interpret as a factor-of-two metallicity gradient in the young stellar populations. They connect these findings to a scenario in which the last pericenter passage (~200–230 Myr ago) stripped metal-poor gas from NGC 4485, mixed it with NGC 4490's gas, and fueled the current star formation.

Significance. The dataset and photometric analysis are impressive: 18 million artificial stars, per-tile completeness, strict quality cuts, and public catalogs at MAST are notable strengths. If the burst chronology and the metallicity gradient survive quantitative scrutiny, the paper would provide valuable resolved-stellar evidence on how dwarf-dwarf interactions drive starbursts and chemical redistribution, and it would support the Pearson et al. (2018) interaction history with independent data. However, the paper's central physical interpretation currently rests on qualitative CMD feature identification and on metallicity assumptions that were chosen to reproduce the very colors later used to infer the gradient. The system is clearly worth detailed study; the manuscript needs stronger quantitative support before the interaction-scenario claims can be accepted.

major comments (4)
  1. [§3.2 and §3.3] Section 3.2 adopts [Fe/H] = -0.6 for NGC 4485 and -0.3 for NGC 4490 'to fit the color of the very young stars in the RSG sequences.' Section 3.3 then interprets the ~0.2 mag median color offset between the RSG sequences of tiles 5 and 9 as a 'significant chemical composition gradient' and a factor-of-two metallicity difference. Since the assumed metallicities were chosen to reproduce those exact colors, the gradient is partly an input assumption rather than an independent measurement. Please report the median RSG colors per tile, the model color-metallicity relation at fixed age, and a fit varying metallicity, age, and extinction simultaneously with uncertainties. This is needed because the gas-stripping/mixing scenario rests on this gradient.
  2. [§3.3, Fig. 7] Internal reddening is dismissed because the upper-MS blue edge does not shift, but the test is qualitative. Differential extinction between the upper-MS and RSG, grey dust, or dust preferentially associated with the young evolved stars could shift the RSG by ~0.2 mag without a detectable upper-MS shift. Figure 11 actually shows reddened RGB stars in the same bridge, so dust is present. Please place the reddening vector on the CMD, compute the E(B-V) needed to explain the offset and the expected upper-MS shift, and test whether the different RSG gaps/mass ranges in tiles 5 and 9 can produce the offset through age/mass differences.
  3. [§3.2, §4] Section 4 states the RSG gap 'can only be explained' by a 5-30 Myr burst. The gap is visually suggestive, but no synthetic-CMD simulation, completeness-corrected luminosity function, or significance test is shown. Also, the age assignments in Section 3.4 use synthetic CMDs generated with the same assumed [Fe/H] values; a wrong metallicity would shift the derived ages and the claimed 100-200 Myr spatial concentration. Please provide quantitative mock-CMD tests or a full SFH fit to support the burst chronology.
  4. [§3.3] The cited SITELLE gas-phase metallicity map (Duarte Puertas et al., in prep) is not shown. Since it would be the strongest external validation of the gradient, either include a quantitative comparison or explicitly label the stellar gradient as tentative pending that analysis.
minor comments (4)
  1. [§2] Typo: 'Nevetheless' in the paragraph on filter choice; also 'galaxys’' should be 'galaxies''.
  2. [§3.4] The text refers to 'The middle panel of Figure 9' when discussing 200 Myr–1 Gyr C-rich AGB stars; this panel is in Figure 10 (the middle panel of Figure 10).
  3. [§3.2/Fig. 6] The isochrone legend labels are small and the TPAGB opacity choice makes the C-rich AGB comparison hard to read; consider enlarging annotations or providing an online interactive figure.
  4. [§2.2/Fig. 3] The completeness curves in Figure 3 are informative but crowded; a table of 50% completeness magnitudes per tile/filter would be useful.

Circularity Check

1 steps flagged · score 6.0 of 10

Metallicity gradient claim is a fitted input: [Fe/H] values were chosen to match the RSG colors, then the same RSG color offset is reported as an independent chemical gradient.

  1. fitted input called prediction [Section 3.2 (Isochrones comparison) and Section 3.3 (Metallicity Gradient), summarized in Section 4]
    "To fit the color of the very young stars in the RSG sequences, we assumed two different metallicity values for the two galaxies: [Fe/H] = −0.6 for NGC 4485 (i.e. tile 1 and 5); and [Fe/H] = −0.3 for the rest of the tiles belonging to NGC 4490 ... We observe a clear shift of ∼ 0.2 mag in the median color of the two RSG sequences ... This finding confirms the presence of a significant chemical composition gradient among the young stellar populations of the bridge between the two dwarf galaxies."

    The two adopted metallicities differ by 0.3 dex (a factor of about two) and were explicitly chosen to reproduce the RSG colors of the two galaxies. The subsequent claim that the observed 0.2 mag RSG color offset between tile 5 and tile 9 is a 'significant chemical composition gradient' and a 'factor of two difference in the metal content' therefore restates the input [Fe/H] difference rather than measuring it independently. The color offset is an observed quantity, but its conversion into a metallicity gradient is the same assumption used in the isochrone fit. The non-shift of the upper-MS excludes uniform foreground reddening only; it does not test whether an age/mass-distribution difference or non-uniform extinction could produce the RSG offset, and no quantitative model with a single me

full rationale

Most of the paper's results are based on measured CMD features and are self-contained or externally supported: the age-dated bursts rely on isochrone morphology (e.g., the RSG gap), the bridge/spatial distributions come from star counts, and the comparison with Pearson et al. (2018) uses an independent N-body simulation. However, the abstract and summary's 'significant metallicity gradient' is not an independent measurement. Section 3.2 states that [Fe/H] = -0.6 and -0.3 were assumed 'to fit the color of the very young stars in the RSG sequences,' and Section 3.3 then presents the observed RSG color shift of ~0.2 mag as confirmation of a chemical gradient. The quoted 'factor of two difference in metal content' is simply the difference between the two assumed metallicities. This is a fitted-input-called-observation circularity for that specific claim. The qualitative upper-MS reddening test is useful but does not break the degeneracy between metallicity, age distribution, and non-uniform dust. Other self-citations (e.g., Correnti et al. 2025b for photometric cuts, Adamo et al. in prep for the survey) are not load-bearing for the main claims. The Duarte Puertas et al. (in prep) gas-phase result is cited as supporting but is not shown and includes a co-author; nonetheless, the central metallicity-gradient claim already reduces to the input assumption. Therefore the score is 6: one headline result is partially circular, while the rest of the analysis retains independent content.

Assumptions & free parameters 2 free parameters · 5 assumptions · 0 invented entities

The paper introduces no new physical entities. Its headline results rest on two hand-assigned metallicity values, on the PARSEC-COLIBRI stellar model grid, on literature distance and reddening, and on the Pearson et al. N-body pericenter timing. The free-parameter count is low, but one of the two fitted values directly feeds the metallicity-gradient claim.

free parameters (2)
  • [Fe/H] of young populations, NGC 4485 = -0.6
    Adopted in Section 3.2 to fit the RSG color, and the value directly influences the reported metallicity gradient in Section 3.3.
  • [Fe/H] of young populations, NGC 4490 = -0.3
    Adopted in Section 3.2 to fit the RSG color; the 0.2 mag shift between tile 5 and 9 is interpreted as a factor of two metallicity difference, so this is an input to the headline gradient claim.
assumptions (5)
  • domain assumption Distance modulus (m-M)0 = 29.70 and E(B-V) = 0.15 are adopted from Calzetti et al. 2015 / Sabbi et al. 2018
    Used for all isochrone comparisons in Section 3.2; a wrong distance or reddening would shift derived ages and masses.
  • domain assumption PARSEC-COLIBRI stellar models correctly predict NIR magnitudes and colors, including the RSG luminosity-age anti-correlation and TPAGB colors
    All age and metallicity inferences in Sections 3.2 to 3.4 depend on this model grid; the paper acknowledges TPAGB uncertainties but applies the same trust to the RSG and MS phases.
  • domain assumption The RSG sequence gap in tiles 5, 9, and 10 is a true deficit of intermediate-age stars, not photometric incompleteness or dust extinction
    The burst interpretation in Sections 3.2 and 4 rests on this; completeness limits are quoted, but the gap is not quantitatively compared against completeness-corrected synthetic CMDs.
  • domain assumption The Pearson et al. (2018) N-body pericenter timing of about 230 Myr ago is correct
    Used to claim 'very good agreement' with the 100-200 Myr burst in Sections 3.2 and 4; if the simulation timing is wrong, the link between the burst and the encounter weakens.
  • domain assumption Kroupa IMF and constant SFR over the last 800 Myr for the synthetic CMDs used in age assignment
    The age binning procedure in Section 3.4 assumes these to assign ages to observed stars; the resulting spatial maps inherit these assumptions.

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Cite this review

Pith. "Pith review of FEAST: JWST/NIRCam view of the Resolved Stellar Populations of the Interacting Dwarf Galaxies NGC~4485/NGC~4490." pith.science (2026). https://pith.science/paper/NIKHMFEG

@misc{pith2026250901740,
  author       = {Pith},
  title        = {Pith review of: FEAST: JWST/NIRCam view of the Resolved Stellar Populations of the Interacting Dwarf Galaxies NGC~4485/NGC~4490},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/NIKHMFEG}},
  note         = {Machine review of arXiv:2509.01740}
}
abstract

We present new JWST/NIRCam observations of the interacting dwarf galaxy system NGC 4485/NGC 4490 (a.k.a. Arp 269), obtained as part of the Cycle 1 Feedback in Emerging extrAgalactic Star clusTers (FEAST) program. NGC 4485 and NGC 4490 form the closest known pair of interacting late-type dwarf galaxies (at $\sim 7.4$ Mpc), excluding the Magellanic Clouds. Near-infrared color-magnitude diagrams (CMDs) reveal a wide range of stellar populations in both galaxies, including young ($\lesssim 200$ Myr) upper main sequence stars, core helium-burning stars, and oxygen-rich asymptotic giant branch (AGB) stars. We also identify intermediate-age ($\sim 200$ Myr -- $1$ Gyr) carbon-rich AGB stars and a well-populated old ($\gtrsim 1$ Gyr) red giant branch (RGB). The CMDs show two distinct bursts of star formation beginning $\sim 30$ Myr and $\sim 200$ Myr ago, the latter consistent with the most recent pericenter passage predicted by N-body simulations. The spatial distribution of stars reveals a tidal bridge extending from NGC 4485 and connecting to the disk of NGC 4490. Compact star-forming regions are seen along NGC 4490's spiral arms, possibly originating from its infrared nucleus. A significant metallicity gradient is observed in the young stellar populations forming the bridge. These findings suggest that during the last pericenter passage, gas was stripped from NGC 4485 via tidal forces or ram pressure, accreted by NGC 4490, and mixed with in-situ material, fueling ongoing star formation. This system provides a unique nearby laboratory for studying how tidal interactions shape the star formation and chemical enrichment history of dwarf galaxies.

Figures

Figures reproduced from arXiv: 2509.01740 by the authors.

Figure 1
Figure 1. Footprint for the FEAST JWST/NIRCam mo￾saic of NGC 4485/NGC 4490 (white rectangle) overlaid upon an optical-band image adopted from the Panoramic Sur￾vey Telescope and Rapid Response System (Pan-STARRS, Chambers et al. 2016). The two dwarf galaxies are labeled. North is up, east is to the left. 2. OBSERVATIONS & DATA REDUCTION [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Color composite image of NGC 4485/NGC 4490, constructed by combining the NIRCam observations obtained as part of the FEAST program in F115W (blue channel), F200W (green channel), and F444W (red channel). The field of view is divided into 18 tiles, which are outlined with dashed white lines and numbered from left to right, bottom to top. The F115W and F200W trace the stellar continuum, while dust emission from star-f… view at source ↗
Figure 3
Figure 3. NIRCam’s F200W image, with superimposed for each tile the completeness of the photometry as a function of magnitude, derived from our ASTs, in both the F115W (blue) and F200W (red) filters. The 50% completeness level is marked by the dashed-gray line, while the magnitude at which this limit is reached in each filter is marked by the dashed-vertical lines [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figures from the paper (10 more)
Figure 4
Figure 4. Figure 4: mF200W vs. mF115W − mF200W CMDs for each tile, displayed on top of the F200W reference image of the NGC 4485/NGC 4490 system. The high-density regions of the CMDs have been binned and color coded according to the number of stars in each bin (see colorbar on the top). m…
Figure 5
Figure 5. Figure 5: Zoom-ins of the CMDs of tile 1 (left panel) and tile 5 (right panel), with some of the features discussed in Section 3.1 & 3.2 highlighted and labeled accordingly. The high-density regions in the diagrams are binned and color-coded, ranging from black to white accordin…
Figure 6
Figure 6. Figure 6: CMDs of tile 1, 5, 9, 10, 12, and 14 covering different regions of both NGC 4485 and NGC 4490. Each CMD is binned and color coded according to the density of stars. Different sets of PARSEC-COLIBRI isochrones are also plotted, assuming a distance modulus of (m − M)0 = …
Figure 8
Figure 8. Figure 8: CMD of NGC 4485 (i.e., tile 1, 2, 3, 4, and 5) showing our selection of three different stellar populations, tracing different epochs in the life of the galaxy. MS, BL, RSG, and O-rich AGB stars younger than 200 Myr in blue. C-rich AGBs between ∼ 200 Myr and ∼ 1 Gyr in…
Figure 7
Figure 7. Figure 7: Bottom panel: Comparison between the CMDs of tile 5 (red points) and tile 9 (blue points). Top panel: Normilized distributions as a function of color of the upper￾MS and RSG sequences for tile 5 and 9, after the exclusion of the shaded area to avoid contamination from …
Figure 9
Figure 9. Figure 9: CMDs and spatial distributions of NGC 4485/NGC 4490 stars in different age intervals: age ≤ 25 Myr, 25 Myr < age ≤ 50 Myr, and 50 Myr < age ≤ 100 Myr. Left panels: NGC 4485 (upper panel) and NGC 4490 (lower panel) CMDs, with the stars in the selected age intervals mark…
Figure 10
Figure 10. Figure 10: Same as [PITH_FULL_IMAGE:figures/full_fig_p012_10.png]
Figure 11
Figure 11. Figure 11: Left panel: CMD of the entire NIRCam FoV, with the selected populations of young stars (in blue) and reddened RGBs (in red). Right panel: comparison between the spatial distribution in the bridge region of reddened RGB stars (in red), and our selection of bona-fide yo…
Figure 12
Figure 12. Figure 12: CMDs of tile 2, 3, 4, 6, 7, and 8. See [PITH_FULL_IMAGE:figures/full_fig_p017_12.png]
Figure 13
Figure 13. Figure 13: CMDs of tile 11, 13, 15, 16, 17, and 18. See [PITH_FULL_IMAGE:figures/full_fig_p018_13.png]

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Works this paper leans on

91 extracted references · 27 canonical work pages

  1. [1]

    2022, Nature Astronomy, 6, 48, doi: 10.1038/s41550-021-01575-x

    Annibali, F., & Tosi, M. 2022, Nature Astronomy, 6, 48, doi: 10.1038/s41550-021-01575-x

  2. [2]

    2016, ApJL, 826, L27, doi: 10.3847/2041-8205/826/2/L27

    Annibali, F., Nipoti, C., Ciotti, L., et al. 2016, ApJL, 826, L27, doi: 10.3847/2041-8205/826/2/L27

  3. [3]

    2020, MNRAS, 491, 5101, doi: 10.1093/mnras/stz3185

    Annibali, F., Beccari, G., Bellazzini, M., et al. 2020, MNRAS, 491, 5101, doi: 10.1093/mnras/stz3185

  4. [4]

    K., et al

    Annibali, F., Pinna, E., Hunt, L. K., et al. 2023, ApJL, 942, L23, doi: 10.3847/2041-8213/acab63 Astropy Collaboration, Robitaille, T. P., Tollerud, E. J., et al. 2013, A&A, 558, A33, doi: 10.1051/0004-6361/201322068 Astropy Collaboration, Price-Whelan, A. M., Sip˝ ocz, B. M., et al. 2018, AJ, 156, 123, doi: 10.3847/1538-3881/aabc4f Astropy Collaboration,...

  5. [5]

    2005, MNRAS, 356, 680, doi: 10.1111/j.1365-2966.2004.08510.x

    Bekki, K., & Chiba, M. 2005, MNRAS, 356, 680, doi: 10.1111/j.1365-2966.2004.08510.x

  6. [6]

    2004, A&A, 424, 199, doi: 10.1051/0004-6361:20035910

    Origlia, L. 2004, A&A, 424, 199, doi: 10.1051/0004-6361:20035910

  7. [7]

    2024, A&A, 691, A42, doi: 10.1051/0004-6361/202449575

    Bellazzini, M., & Pascale, R. 2024, A&A, 691, A42, doi: 10.1051/0004-6361/202449575

  8. [8]

    J., et al

    Belokurov, V., Erkal, D., Deason, A. J., et al. 2017, MNRAS, 466, 4711, doi: 10.1093/mnras/stw3357

Show all 91 references
  1. [9]

    Deason, A. J. 2018, MNRAS, 478, 611, doi: 10.1093/mnras/sty982

  2. [10]

    B., Evans, N

    Belokurov, V., Zucker, D. B., Evans, N. W., et al. 2006, ApJL, 642, L137, doi: 10.1086/504797

  3. [11]

    2010, ApJL, 721, L97, doi: 10.1088/2041-8205/721/2/L97

    Besla, G., Kallivayalil, N., Hernquist, L., et al. 2010, ApJL, 721, L97, doi: 10.1088/2041-8205/721/2/L97

  4. [12]

    2024a, MNRAS, 527, 5339, doi: 10.1093/mnras/stad3524

    Bortolini, G., Cignoni, M., Sacchi, E., et al. 2024a, MNRAS, 527, 5339, doi: 10.1093/mnras/stad3524

  5. [13]

    2024b, A&A, 689, A146, doi: 10.1051/0004-6361/202450632

    Bortolini, G., ¨Ostlin, G., Habel, N., et al. 2024b, A&A, 689, A146, doi: 10.1051/0004-6361/202450632

  6. [14]

    2012, MNRAS, 427, 127, doi: 10.1111/j.1365-2966.2012.21948.x

    Bressan, A., Marigo, P., Girardi, L., et al. 2012, MNRAS, 427, 127, doi: 10.1111/j.1365-2966.2012.21948.x

  7. [15]

    C., Sabbi, E., et al

    Calzetti, D., Lee, J. C., Sabbi, E., et al. 2015, AJ, 149, 51, doi: 10.1088/0004-6256/149/2/51

  8. [16]

    L., Sand, D

    Carlin, J. L., Sand, D. J., Price, P., et al. 2016, ApJL, 828, L5, doi: 10.3847/2041-8205/828/1/L5

  9. [17]

    C., Magnier, E

    Chambers, K. C., Magnier, E. A., Metcalfe, N., et al. 2016, arXiv e-prints, arXiv:1612.05560, doi: 10.48550/arXiv.1612.05560

  10. [18]

    P., et al

    Cignoni, M., Sabbi, E., van der Marel, R. P., et al. 2016, ApJ, 833, 154, doi: 10.3847/1538-4357/833/2/154

  11. [20]

    P., Cole, S., Frenk, C

    Cooper, A. P., Cole, S., Frenk, C. S., et al. 2010, MNRAS, 406, 744, doi: 10.1111/j.1365-2966.2010.16740.x

  12. [21]

    2025a, arXiv e-prints, arXiv:2502.18171

    Correnti, M., Annibali, F., Bellazzini, M., et al. 2025a, arXiv e-prints, arXiv:2502.18171. https://arxiv.org/abs/2502.18171

  13. [22]

    2025b, arXiv e-prints, arXiv:2507.03420, doi: 10.48550/arXiv.2507.03420 Crnojevi´ c, D., Sand, D

    Correnti, M., Bortolini, G., Dell’Agli, F., et al. 2025b, arXiv e-prints, arXiv:2507.03420, doi: 10.48550/arXiv.2507.03420 Crnojevi´ c, D., Sand, D. J., Spekkens, K., et al. 2016, ApJ, 823, 19, doi: 10.3847/0004-637X/823/1/19

  14. [23]

    2008, Nature, 454, 735, doi: 10.1038/nature07153

    Diemand, J., Kuhlen, M., Madau, P., et al. 2008, Nature, 454, 735, doi: 10.1038/nature07153

  15. [24]

    C., Skillman, E

    Dohm-Palmer, R. C., Skillman, E. D., Saha, A., et al. 1997, AJ, 114, 2527, doi: 10.1086/118665

  16. [25]

    2016, DOLPHOT: Stellar photometry, Astrophysics Source Code Library, record ascl:1608.013

    Dolphin, A. 2016, DOLPHOT: Stellar photometry, Astrophysics Source Code Library, record ascl:1608.013. http://ascl.net/1608.013 20

  17. [26]

    Dolphin, A. E. 2000, PASP, 112, 1383, doi: 10.1086/316630

  18. [27]

    2019, MNRAS, 485, 3930, doi: 10.1093/mnras/stz627

    Drissen, L., Martin, T., Rousseau-Nepton, L., et al. 2019, MNRAS, 485, 3930, doi: 10.1093/mnras/stz627

  19. [28]

    Elmegreen, B. G. 1998, in Astronomical Society of the Pacific Conference Series, Vol. 148, Origins, ed. C. E

  20. [29]

    Woodward, J. M. Shull, & H. A. Thronson, Jr., 150, doi: 10.48550/arXiv.astro-ph/9712352

  21. [30]

    Wittenmyer, R. A. 1998, AJ, 115, 1433, doi: 10.1086/300301

  22. [31]

    S., White, S

    Frenk, C. S., White, S. D. M., Davis, M., & Efstathiou, G. 1988, ApJ, 327, 507, doi: 10.1086/166213 Gaia Collaboration, Vallenari, A., Brown, A. G. A., et al. 2023, A&A, 674, A1, doi: 10.1051/0004-6361/202243940

  23. [32]

    T., & Noguchi, M

    Gardiner, L. T., & Noguchi, M. 1996, MNRAS, 278, 191, doi: 10.1093/mnras/278.1.191

  24. [33]

    C., & Rosales-Ortega, F

    Garner, R., Mihos, J. C., & Rosales-Ortega, F. F. 2025, ApJ, 982, 143, doi: 10.3847/1538-4357/adbbd0

  25. [34]

    F., & Bland-Hawthorn, J

    Guglielmo, M., Lewis, G. F., & Bland-Hawthorn, J. 2014, MNRAS, 444, 1759, doi: 10.1093/mnras/stu1549

  26. [35]

    2024, ApJ, 971, 108, doi: 10.3847/1538-4357/ad5343

    Habel, N., Nally, C., Lenki´ c, L., et al. 2024, ApJ, 971, 108, doi: 10.3847/1538-4357/ad5343

  27. [36]

    2009, AJ, 137, 4643, doi: 10.1088/0004-6256/137/6/4643

    Hurlock, S. 2009, AJ, 137, 4643, doi: 10.1088/0004-6256/137/6/4643

  28. [37]

    R., Millman, K

    Harris, C. R., Millman, K. J., van der Walt, S. J., et al. 2020, Nature, 585, 357–362, doi: 10.1038/s41586-020-2649-2

  29. [38]

    Helmi, A., & White, S. D. M. 1999, MNRAS, 307, 495, doi: 10.1046/j.1365-8711.1999.02616.x

  30. [39]

    R., McConnachie, A

    Higgs, C. R., McConnachie, A. W., Irwin, M., et al. 2016, MNRAS, 458, 1678, doi: 10.1093/mnras/stw257

  31. [40]

    Hunter, J. D. 2007, Computing in science & engineering, 9, 90

  32. [41]

    2001, Nature, 412, 49, doi: 10.1038/35083506

    Tanvir, N. 2001, Nature, 412, 49, doi: 10.1038/35083506

  33. [42]

    Suntzeff, N. B. 1997, AJ, 113, 634, doi: 10.1086/118283

  34. [43]

    I., & Thuan, T

    Izotov, Y. I., & Thuan, T. X. 2009, ApJ, 690, 1797, doi: 10.1088/0004-637X/690/2/1797

  35. [44]

    A., & Mandel, E

    Joye, W. A., & Mandel, E. 2003, in Astronomical data analysis software and systems XII, Vol. 295, 489

  36. [45]

    V., Zivick, P., et al

    Kallivayalil, N., Sales, L. V., Zivick, P., et al. 2018, ApJ, 867, 19, doi: 10.3847/1538-4357/aadfee

  37. [46]

    D., Kaisina, E

    Karachentsev, I. D., Kaisina, E. I., & Makarov, D. I. 2018, MNRAS, 479, 4136, doi: 10.1093/mnras/sty1774

  38. [47]

    D., & Kroupa, P

    Karachentsev, I. D., & Kroupa, P. 2024, MNRAS, 528, 2805, doi: 10.1093/mnras/stae184

  39. [48]

    V., Gnedin, O

    Kravtsov, A. V., Gnedin, O. Y., & Klypin, A. A. 2004, ApJ, 609, 482, doi: 10.1086/421322

  40. [49]

    2001, MNRAS, 322, 231, doi: 10.1046/j.1365-8711.2001.04022.x

    Kroupa, P. 2001, MNRAS, 322, 231, doi: 10.1046/j.1365-8711.2001.04022.x

  41. [50]

    R., Struck, C., & Smith, B

    Lawrence, A., Kerton, C. R., Struck, C., & Smith, B. J. 2020, ApJ, 891, 11, doi: 10.3847/1538-4357/ab6c6a

  42. [51]

    G., Freedman, W

    Lee, M. G., Freedman, W. L., & Madore, B. F. 1993, ApJ, 417, 553, doi: 10.1086/173334

  43. [52]

    2023, MNRAS, 523, 3905, doi: 10.1093/mnras/stad1281

    Liu, Y., Zhu, M., Yu, H., et al. 2023, MNRAS, 523, 3905, doi: 10.1093/mnras/stad1281

  44. [53]

    2001, A&A, 373, 555, doi: 10.1051/0004-6361:20010596

    Maeder, A., & Meynet, G. 2001, A&A, 373, 555, doi: 10.1051/0004-6361:20010596

  45. [54]

    2006, AJ, 132, 2729, doi: 10.1086/508925

    Makarov, D., Makarova, L., Rizzi, L., et al. 2006, AJ, 132, 2729, doi: 10.1086/508925

  46. [55]

    Mandal, S., & Kerton, C. R. 2024, MNRAS, 529, 953, doi: 10.1093/mnras/stae500

  47. [56]

    2017, ApJ, 835, 77, doi: 10.3847/1538-4357/835/1/77 Mart ´ ınez-Delgado, D., Gabany, R

    Marigo, P., Girardi, L., Bressan, A., et al. 2017, ApJ, 835, 77, doi: 10.3847/1538-4357/835/1/77 Mart ´ ınez-Delgado, D., Gabany, R. J., Crawford, K., et al. 2010, AJ, 140, 962, doi: 10.1088/0004-6256/140/4/962

  48. [57]

    2006, MNRAS, 369, 1021, doi: 10.1111/j.1365-2966.2006.10403.x

    Moore, B. 2006, MNRAS, 369, 1021, doi: 10.1111/j.1365-2966.2006.10403.x

  49. [58]

    W., Irwin, M

    McConnachie, A. W., Irwin, M. J., Ibata, R. A., et al. 2009, Nature, 461, 66, doi: 10.1038/nature08327

  50. [59]

    McQuinn, K. B. W., B. Newman, M. J., Savino, A., et al. 2024, ApJ, 961, 16, doi: 10.3847/1538-4357/ad1105

  51. [60]

    C., Lenki´ c, L., et al

    Nally, C., Jones, O. C., Lenki´ c, L., et al. 2024, MNRAS, 531, 183, doi: 10.1093/mnras/stae1163

  52. [61]

    2013, MNRAS, 434, 2390, doi: 10.1093/mnras/stt1175

    Nanni, A., Bressan, A., Marigo, P., & Girardi, L. 2013, MNRAS, 434, 2390, doi: 10.1093/mnras/stt1175

  53. [62]

    A., D’Onghia, E., & Fox, A

    Pardy, S. A., D’Onghia, E., & Fox, A. J. 2018, ApJ, 857, 101, doi: 10.3847/1538-4357/aab95b

  54. [63]

    A., D’Onghia, E., Navarro, J

    Pardy, S. A., D’Onghia, E., Navarro, J. F., et al. 2020, MNRAS, 492, 1543, doi: 10.1093/mnras/stz3192

  55. [64]

    2024, A&A, 688, A144, doi: 10.1051/0004-6361/202348991

    Pascale, R., Annibali, F., Tosi, M., et al. 2024, A&A, 688, A144, doi: 10.1051/0004-6361/202348991

  56. [65]

    2020, MNRAS, 498, 3283, doi: 10.1093/mnras/staa2565

    Pastorelli, G., Marigo, P., Girardi, L., et al. 2020, MNRAS, 498, 3283, doi: 10.1093/mnras/staa2565

  57. [66]

    2020, ApJ, 893, 121, doi: 10.3847/1538-4357/ab7b75

    Patel, E., Kallivayalil, N., Garavito-Camargo, N., et al. 2020, ApJ, 893, 121, doi: 10.3847/1538-4357/ab7b75

  58. [67]

    C., Besla, G., et al

    Pearson, S., Privon, G. C., Besla, G., et al. 2018, MNRAS, 480, 3069, doi: 10.1093/mnras/sty2052

  59. [68]

    Peebles, P. J. E. 1982, ApJL, 263, L1, doi: 10.1086/183911

  60. [69]

    S., & Thuan, T

    Pilyugin, L. S., & Thuan, T. X. 2007, ApJ, 669, 299, doi: 10.1086/521597

  61. [70]

    H., Wright, G

    Rieke, G. H., Wright, G. S., B¨ oker, T., et al. 2015, PASP, 127, 584, doi: 10.1086/682252

  62. [71]

    J., Kelly, D

    Rieke, M. J., Kelly, D. M., Misselt, K., et al. 2023, PASP, 135, 028001, doi: 10.1088/1538-3873/acac53

  63. [72]

    P., Robert, C., et al

    Rousseau-Nepton, L., Martin, R. P., Robert, C., et al. 2019, MNRAS, 489, 5530, doi: 10.1093/mnras/stz2455 21

  64. [73]

    2018, ApJS, 235, 23, doi: 10.3847/1538-4365/aaa8e5

    Sabbi, E., Calzetti, D., Ubeda, L., et al. 2018, ApJS, 235, 23, doi: 10.3847/1538-4365/aaa8e5

  65. [74]

    2016, ApJ, 830, 3, doi: 10.3847/0004-637X/830/1/3

    Sacchi, E., Annibali, F., Cignoni, M., et al. 2016, ApJ, 830, 3, doi: 10.3847/0004-637X/830/1/3

  66. [75]

    2024, A&A, 691, A65, doi: 10.1051/0004-6361/202450106

    Sacchi, E., Bellazzini, M., Annibali, F., et al. 2024, A&A, 691, A65, doi: 10.1051/0004-6361/202450106

  67. [76]

    1998, MNRAS, 298, 166, doi: 10.1046/j.1365-8711.1998.01598.x

    Salaris, M., & Cassisi, S. 1998, MNRAS, 298, 166, doi: 10.1046/j.1365-8711.1998.01598.x

  68. [77]

    D., & Geha, M

    Simon, J. D., & Geha, M. 2007, ApJ, 670, 313, doi: 10.1086/521816

  69. [78]

    J., Giroux, M

    Smith, B. J., Giroux, M. L., Struck, C., & Hancock, M. 2010, AJ, 139, 1212, doi: 10.1088/0004-6256/139/3/1212

  70. [79]

    Taylor, M. B. 2005, in Astronomical Society of the Pacific Conference Series, Vol. 347, Astronomical Data Analysis Software and Systems XIV, ed. P. Shopbell, M. Britton, & R. Ebert, 29

  71. [80]

    A., Hunter, D

    Thronson, Jr., H. A., Hunter, D. A., Casey, S., Latter, W. B., & Harper, D. A. 1989, ApJ, 339, 803, doi: 10.1086/167337

  72. [81]

    A., Galazutdinova, O

    Tikhonov, N. A., Galazutdinova, O. A., & Lebedev, V. S. 2014, Astronomy Letters, 40, 1, doi: 10.1134/S1063773714010058

  73. [82]

    2009, ARA&A, 47, 371, doi: 10.1146/annurev-astro-082708-101650

    Tolstoy, E., Hill, V., & Tosi, M. 2009, ARA&A, 47, 371, doi: 10.1146/annurev-astro-082708-101650

  74. [83]

    2018, PhR, 730, 1, doi: 10.1016/j.physrep.2017.11.004

    Tulin, S., & Yu, H.-B. 2018, PhR, 730, 1, doi: 10.1016/j.physrep.2017.11.004

  75. [84]

    2014, MNRAS, 439, 977, doi: 10.1093/mnras/stu028

    Ventura, P., Dell’Agli, F., Schneider, R., et al. 2014, MNRAS, 439, 977, doi: 10.1093/mnras/stu028

  76. [85]

    A., & Guzman-Ramirez, L

    Ventura, P., Karakas, A., Dell’Agli, F., Garc ´ ıa-Hern´ andez, D. A., & Guzman-Ramirez, L. 2018, MNRAS, 475, 2282, doi: 10.1093/mnras/stx3338

  77. [86]

    E., et al

    Virtanen, P., Gommers, R., Oliphant, T. E., et al. 2020, Nature Methods, 17, 261, doi: 10.1038/s41592-019-0686-2

  78. [87]

    R., McQuinn, K

    Weisz, D. R., McQuinn, K. B. W., Savino, A., et al. 2023, ApJS, 268, 15, doi: 10.3847/1538-4365/acdcfd

  79. [88]

    R., Dolphin, A

    Weisz, D. R., Dolphin, A. E., Savino, A., et al. 2024, ApJS, 271, 47, doi: 10.3847/1538-4365/ad2600 Wes McKinney. 2010, in Proceedings of the 9th Python in Science Conference, ed. St´ efan van der Walt & Jarrod Millman, 56 – 61, doi: 10.25080/Majora-92bf1922-00a

  80. [89]

    S., et al

    Wheeler, C., O˜ norbe, J., Bullock, J. S., et al. 2015, MNRAS, 453, 1305, doi: 10.1093/mnras/stv1691

  81. [90]

    White, S. D. M., & Frenk, C. S. 1991, ApJ, 379, 52, doi: 10.1086/170483

  82. [91]

    White, S. D. M., & Rees, M. J. 1978, MNRAS, 183, 341, doi: 10.1093/mnras/183.3.341

  83. [92]

    2024, ApJ, 965, 3, doi: 10.3847/1538-4357/ad2f2d

    Zhang, L.-Y., Zhao, Y., & Zhang, H.-X. 2024, ApJ, 965, 3, doi: 10.3847/1538-4357/ad2f2d

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