pith. sign in

arxiv: 2605.21588 · v1 · pith:WLNKOM5Rnew · submitted 2026-05-20 · 🌌 astro-ph.GA

Decomposing cool stellar populations with H-band spectral fluctuations: Long-period variable stars in NGC 5128 and carbon stars in NGC 5102

Russell J. Smith , Anastasia Gvozdenko This is my paper

Pith reviewed 2026-05-22 09:26 UTC · model grok-4.3

classification 🌌 astro-ph.GA
keywords integral field spectroscopystellar populationslong-period variablescarbon starsNGC 5128NGC 5102H-band spectraprincipal component analysis
0
0 comments X

The pith

Pixel-to-pixel H-band variations isolate mid-M giant spectra plus components from long-period variables and carbon stars.

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

The authors apply principal components analysis to integral-field H-band spectra of two galaxies to separate the contributions of different cool giant stars. In the old bulge of NGC 5128 the dominant fluctuation matches a mid-M giant with strong CO bandheads, while a second component matches the cool phases of long-period variable stars. In the post-starburst galaxy NGC 5102 the second component instead shows the 1.77-micron C2 bandhead that marks carbon stars. The signals appear because each pixel randomly samples stars from the same underlying population. The work shows that integral-field data can extract details about the stellar mix that are invisible in the total integrated spectrum.

Core claim

The paper establishes that in NGC 5128 the pixel-to-pixel variation is dominated by a mid-M giant spectrum with prominent CO bandheads and a second component from cool phases of long-period variable stars, while in NGC 5102 the second eigenspectrum shows a strong 1.77 micron C2 bandhead characteristic of carbon stars; these signals arise in near-resolved point-like sources without large-scale variation, consistent with each pixel sampling stars randomly from a common underlying population.

What carries the argument

Principal components analysis of the spectra recorded in individual pixels, which isolates the main modes of spectral variation produced by different types of cool giant stars.

If this is right

  • Models of old stellar populations must incorporate the cool phases of long-period variables to reproduce the observed spectral fluctuations.
  • The C2 bandhead feature allows carbon stars to be identified in galaxies that contain post-starburst populations through their contribution to pixel variations.
  • Integral-field observations yield information on the mix of giant stars that is lost when only the total spectrum of a galaxy is measured.
  • Two-epoch observations can provide independent confirmation of variable stars through direct detection of their brightness changes.

Where Pith is reading between the lines

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

  • The same pixel-fluctuation technique could be applied to other nearby galaxies to map the spatial distribution of variable stars and carbon stars without resolving individual objects.
  • Stellar population synthesis codes could be tested and improved by requiring them to reproduce the second principal components extracted from real integral-field data.
  • Extending the analysis to additional wavelength ranges might isolate contributions from other stellar types or dust features that are not prominent in the H band.

Load-bearing premise

The pixel-to-pixel signals arise only from random sampling of stars from a uniform population with no significant large-scale spatial changes in stellar content.

What would settle it

A direct comparison showing that the second spectral component in NGC 5128 does not match the H-band spectra of long-period variable stars observed at their coolest phases, or the detection of coherent large-scale gradients in the spectral variations across either galaxy.

Figures

Figures reproduced from arXiv: 2605.21588 by Anastasia Gvozdenko, Russell J. Smith.

Figure 1
Figure 1. Figure 1: The fields observed with ERIS (red) for NGC 5128 (upper panels) and NGC 5102 (lower panels). Also marked is the MUSE-NFM field of S22 in NGC 5128 (blue). The first panel of each row shows a wide field J-band image from Skrutskie et al. (2006), while the second is an archival optical HST image: ACS/F606W for NGC 5128 (Harris et al. 2006); WFPC2/F569W for NGC 5102 (Mitzkus et al. 2017a). In the third panel, … view at source ↗
Figure 2
Figure 2. Figure 2: Fraction of total variance (including observational noise) con￾tributed by each component in the PCA decomposition for the two galaxies. The dotted lines show fits to components 5–15, representing the noise floor in each observation. range 1.49–1.80 𝜇m, to avoid steep throughput variation at the edges of the H-band window, and pixels affected by residual noise spikes were masked. 3.1 NGC 5128 For applicati… view at source ↗
Figure 3
Figure 3. Figure 3: The two leading eigenspectra derived for each target field. In parentheses to the right are the percentage contributions to the total data variance accounted for by each component. The spectra are shown at the full resolution of the data (grey), and after smoothing to enhance visibility of features (black). The wavelengths of some key molecular bandheads and atomic lines are indicated. Below for comparison… view at source ↗
Figure 4
Figure 4. Figure 4: Eigenimages of the PCA decomposition for NGC 5128 (upper panels) and NGC 5102 (lower). All panels are 10 arcsec on a side. For each target, the first panel reproduces the collapsed-cube image for comparison (with the bright star excised in the case of NGC 5102), with a contour showing the pixels selected for the PCA. The second and third panels show the first two eigenimages in greyscale form, while the fi… view at source ↗
read the original abstract

We analyse new H-band integral-field unit observations of two galaxies at ~4 Mpc, using a principal components analysis of pixel spectra to probe their giant star content. In both galaxies, the signals arise in near-resolved point-like sources without large-scale variation, consistent with each pixel sampling stars randomly from a common underlying population. In the (mostly) old bulge of NGC 5128, the observed pixel-to-pixel variation is dominated by a component with a mid-M giant spectrum with prominent CO bandheads. We also recover a smoother second spectral component, apparently driven by contributions from later spectral types. This component is not present in predictions from Poisson-sampled models of old stellar populations; we suggest that it arises from the cool phases of long-period variable stars. (An appendix provides direct evidence for such variables in complementary two-epoch MUSE observations.) In the contrasting galaxy NGC 5102, where a post-starburst stellar population is known to be present, we again find two distinct components. As before, the first component carries the CO bands typical of M-giants. The second eigenspectrum in this younger galaxy shows a strong 1.77 micron C2 bandhead, a feature which is characteristic of carbon stars. Our results highlight the ability of integral field data to access information beyond the total spectrum, even when individual stars cannot be classically resolved.

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

2 major / 2 minor

Summary. The paper applies principal components analysis to H-band integral-field unit spectra of NGC 5128 and NGC 5102 to decompose pixel-to-pixel variations into stellar population components. In the old bulge of NGC 5128 the dominant component matches a mid-M giant spectrum with CO bandheads while a second smoother component is attributed to cool phases of long-period variables (supported by two-epoch MUSE data in an appendix). In NGC 5102 a post-starburst system, the second eigenspectrum instead shows a prominent 1.77 μm C2 bandhead interpreted as arising from carbon stars. The authors argue that the signals originate from near-resolved point sources sampling a common underlying population without large-scale spatial structure.

Significance. If the attributions hold, the work shows that PCA on IFU data can isolate specific cool stellar types (LPVs, carbon stars) beyond what integrated spectra provide, even at distances where classical resolution of individual stars is marginal. The combination of data-driven decomposition, feature matching to known spectra, and direct MUSE confirmation for LPVs is a concrete strength; the approach could be extended to other nearby galaxies to constrain variable-star fractions or carbon-star populations.

major comments (2)
  1. [§3 / results on NGC 5128] §3 (or equivalent methods/results section): the statement that the second component in NGC 5128 'is not present in predictions from Poisson-sampled models' is central to the LPV interpretation, yet the manuscript provides no quantitative description of how those models were constructed, what IMF or age-metallicity assumptions were adopted, or the statistical threshold used to declare the component absent. This weakens the claim that the observed component must be attributed to LPVs rather than an incomplete model.
  2. [Introduction / §2 / discussion of assumptions] The weakest assumption (near-resolved point sources with no large-scale variation) is load-bearing for interpreting the PCA components as stellar-type fluctuations rather than spatial gradients. While the paper states that components lack large-scale structure, no explicit test (e.g., spatial autocorrelation of the PC maps or comparison to simulated gradients) is reported to quantify how well this assumption holds at the ~4 Mpc distance.
minor comments (2)
  1. [Abstract / §2] The abstract and main text would benefit from a brief statement of the wavelength range, spectral resolution, and typical S/N per pixel of the MUSE and IFU data to allow readers to assess the reliability of the 1.77 μm C2 feature identification.
  2. [Figures 2–4 / results] Figure captions (or the relevant results section) should clarify whether the eigenspectra are normalized in a specific way and whether the reported bandhead strengths include formal uncertainties.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive comments and positive recommendation. We address each major comment below and will revise the manuscript accordingly to strengthen the presentation.

read point-by-point responses

  1. Referee: [§3 / results on NGC 5128] §3 (or equivalent methods/results section): the statement that the second component in NGC 5128 'is not present in predictions from Poisson-sampled models' is central to the LPV interpretation, yet the manuscript provides no quantitative description of how those models were constructed, what IMF or age-metallicity assumptions were adopted, or the statistical threshold used to declare the component absent. This weakens the claim that the observed component must be attributed to LPVs rather than an incomplete model.

    Authors: We agree that the current description of the Poisson-sampled models lacks sufficient quantitative detail. In the revised manuscript we will expand §3 to specify the model construction (Monte Carlo sampling of stellar luminosities from an old population), the adopted IMF, the age-metallicity assumptions used for NGC 5128, and the precise statistical criterion (e.g., variance threshold or residual comparison) applied to conclude that the second observed component is absent from the models. This addition will clarify the robustness of the LPV interpretation. revision: yes

  2. Referee: The weakest assumption (near-resolved point sources with no large-scale variation) is load-bearing for interpreting the PCA components as stellar-type fluctuations rather than spatial gradients. While the paper states that components lack large-scale structure, no explicit test (e.g., spatial autocorrelation of the PC maps or comparison to simulated gradients) is reported to quantify how well this assumption holds at the ~4 Mpc distance.

    Authors: We acknowledge that an explicit quantitative test of the no-large-scale-variation assumption would strengthen the paper. In the revision we will add such a test, including computation of the spatial autocorrelation of the principal-component maps together with a comparison against mock data containing imposed large-scale gradients. This will provide a direct metric confirming that the observed signals are consistent with near-resolved point-source sampling at the distance of the galaxies. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected in data-driven PCA decomposition

full rationale

The paper applies principal components analysis directly to observed H-band integral-field unit spectra of NGC 5128 and NGC 5102. The resulting eigenspectra are interpreted by matching prominent features (CO bandheads at known wavelengths, 1.77 micron C2) to established stellar templates, with the second component in NGC 5128 attributed to LPV cool phases based on absence from Poisson models and supporting MUSE evidence in the appendix. All steps are empirical extractions from the data itself; no parameter is fitted to a subset and then relabeled as a prediction, no uniqueness theorem is imported from self-citation, and no ansatz is smuggled via prior work. The derivation chain remains self-contained against external spectral libraries and direct observations.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The analysis rests on standard PCA assumptions and domain knowledge of stellar spectra; no new free parameters or invented entities are introduced beyond linking observed components to known variable star classes.

axioms (2)
  • standard math Principal component analysis separates the dominant independent sources of spectral variation across pixels.
    PCA is applied to pixel spectra to extract the main fluctuation components.
  • domain assumption Each pixel samples stars randomly from a shared underlying population with no large-scale spatial gradients in the signal.
    Stated explicitly in the abstract as consistent with the observed point-like sources.

pith-pipeline@v0.9.0 · 5789 in / 1392 out tokens · 49546 ms · 2026-05-22T09:26:04.383678+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

62 extracted references · 62 canonical work pages · 30 internal anchors

  1. [1]

    Unmixing Hyperspectral Data , url =

    Parra, Lucas and Spence, Clay and Sajda, Paul and Ziehe, Andreas and M\". Unmixing Hyperspectral Data , url =. Advances in Neural Information Processing Systems , editor =

    work page

  2. [2]

    A., okas E

    Evolutionary population synthesis: models, analysis of the ingredients and application to high-z galaxies. , keywords =. doi:10.1111/j.1365-2966.2005.09270.x , archivePrefix =. astro-ph/0410207 , primaryClass =

    work page doi:10.1111/j.1365-2966.2005.09270.x 2005

  3. [3]

    Near Infrared spectroscopy of post-starburst galaxies: a limited impact of TP-AGB stars on galaxy SEDs

    Near-infrared spectroscopy of post-starburst galaxies: a limited impact of TP-AGB stars on galaxy spectral energy distributions. , keywords =. doi:10.1093/mnras/sts126 , archivePrefix =. 1205.4717 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/sts126

  4. [4]

    , year = 1993, month = aug, volume =

    Statistical properties of stellar populations and surface-brightness fluctuations in galaxies. , year = 1993, month = aug, volume =

    work page 1993

  5. [5]

    , keywords =

    Modelling simple stellar populations in the near-ultraviolet to near-infrared with the X-shooter Spectral Library (XSL). , keywords =. doi:10.1051/0004-6361/202142387 , archivePrefix =. 2110.10190 , primaryClass =

    work page doi:10.1051/0004-6361/202142387

  6. [6]

    , keywords =

    The evolution of galactic carbon stars. , keywords =

    work page

  7. [7]

    Dominant dark matter and a counter rotating disc: MUSE view of the low luminosity S0 galaxy NGC 5102

    Dominant dark matter and a counter-rotating disc: MUSE view of the low-luminosity S0 galaxy NGC 5102. , keywords =. doi:10.1093/mnras/stw2677 , archivePrefix =. 1610.04516 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stw2677

  8. [8]

    Ghosts in the Attic: Mapping the Stellar Content of the S0 Galaxy NGC 5102

    Ghosts in the Attic: Mapping the Stellar Content of the S0 Galaxy NGC 5102. , keywords =. doi:10.1088/0004-6256/139/2/680 , archivePrefix =. 0908.2263 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-6256/139/2/680

  9. [9]

    2025, NatAs, 9, 128, doi: 10.1038/s41550-024-02391-9

    Strong spectral features from asymptotic giant branch stars in distant quiescent galaxies. Nature Astronomy , keywords =. doi:10.1038/s41550-024-02391-9 , archivePrefix =. 2403.07414 , primaryClass =

    work page doi:10.1038/s41550-024-02391-9

  10. [10]

    , keywords =

    A library of 0.5 to 2.5 mu m spectra of luminous cool stars. , keywords =. doi:10.1051/aas:2000269 , adsurl =

    work page doi:10.1051/aas:2000269

  11. [11]

    Ubiquitous Time Variability of Integrated Stellar Populations

    Ubiquitous time variability of integrated stellar populations. , keywords =. doi:10.1038/nature15731 , archivePrefix =. 1511.04086 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1038/nature15731

  12. [12]

    Yonsei Evolutionary Population Synthesis (YEPS). II. Spectro-photometric Evolution of Helium-enhanced Stellar Populations. , keywords =. doi:10.3847/1538-4357/aa6f19 , archivePrefix =. 1704.07382 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aa6f19

  13. [13]

    Helium variation due to self-pollution among Globular Cluster stars: consequences on the horizontal branch morphology

    Helium variation due to self-pollution among Globular Cluster stars. Consequences on the horizontal branch morphology. , keywords =. doi:10.1051/0004-6361:20021220 , archivePrefix =. astro-ph/0209331 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361:20021220

  14. [14]

    , keywords =

    Probing the Stellar Populations and Star Formation History of Early-type Galaxies at 0 < z < 1.1 in the Rest-frame Ultraviolet. , keywords =. doi:10.3847/1538-4357/ad3209 , archivePrefix =. 2403.08301 , primaryClass =

    work page doi:10.3847/1538-4357/ad3209

  15. [15]

    Dissolved Massive Metal-Rich Globular Clusters Can Cause the Range of UV Upturn Strengths Found among Early-type Galaxies

    Dissolved Massive Metal-rich Globular Clusters Can Cause the Range of UV Upturn Strengths Found among Early-type Galaxies. , keywords =. doi:10.3847/1538-4357/aab553 , archivePrefix =. 1804.00668 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aab553

  16. [16]

    The effect of helium-enhanced stellar populations on the ultraviolet-upturn phenomenon of early-type galaxies

    The Effect of Helium-enhanced Stellar Populations on the Ultraviolet-upturn Phenomenon of Early-type Galaxies. , keywords =. doi:10.1088/2041-8205/740/2/L45 , archivePrefix =. 1109.3463 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/2041-8205/740/2/l45 2041

  17. [17]

    Modeling the Panchromatic Spectral Energy Distributions of Galaxies

    Modeling the Panchromatic Spectral Energy Distributions of Galaxies. , keywords =. doi:10.1146/annurev-astro-082812-141017 , archivePrefix =. 1301.7095 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1146/annurev-astro-082812-141017

  18. [18]

    , year = 2020, month = aug, volume =

    Evidence for Initial Mass Function Variation in Massive Early-Type Galaxies. , year = 2020, month = aug, volume =. doi:10.1146/annurev-astro-032620-020217 , adsurl =

    work page doi:10.1146/annurev-astro-032620-020217 2020

  19. [19]

    Long Period Variables in NGC 5128 . II. Near-IR properties. , keywords =. doi:10.1051/0004-6361:20034056 , archivePrefix =. astro-ph/0309358 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361:20034056

  20. [20]

    , keywords =

    The Enhanced Resolution Imager and Spectrograph for the VLT. , keywords =. doi:10.1051/0004-6361/202346559 , archivePrefix =. 2304.02343 , primaryClass =

    work page doi:10.1051/0004-6361/202346559

  21. [21]

    Ground-based and Airborne Instrumentation for Astronomy III , year = 2010, editor =

    The MUSE second-generation VLT instrument. Ground-based and Airborne Instrumentation for Astronomy III , year = 2010, editor =. doi:10.1117/12.856027 , archivePrefix =. 2211.16795 , primaryClass =

    work page doi:10.1117/12.856027 2010

  22. [22]

    Ground-based and Airborne Instrumentation for Astronomy IX , year = 2022, editor =

    HARMONI at ELT: overview of the capabilities and expected performance of the ELT's first light, adaptive optics assisted integral field spectrograph. Ground-based and Airborne Instrumentation for Astronomy IX , year = 2022, editor =. doi:10.1117/12.2628834 , adsurl =

    work page doi:10.1117/12.2628834 2022

  23. [23]

    R., 2009, @doi [ ] 10.1111/j.1365-2966.2009.15167.x , http://adsabs.harvard.edu/abs/2009MNRAS.398..607V 398, 607

    PCA Tomography: how to extract information from data cubes. , keywords =. doi:10.1111/j.1365-2966.2009.14530.x , archivePrefix =. 0901.2266 , primaryClass =

    work page doi:10.1111/j.1365-2966.2009.14530.x 2009

  24. [24]

    The Stellar Initial Mass Function in Early-type Galaxies From Absorption Line Spectroscopy. II. Results. , keywords =. doi:10.1088/0004-637X/760/1/71 , archivePrefix =. 1205.6473 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/760/1/71

  25. [25]

    Systematic variation of the stellar Initial Mass Function with velocity dispersion in early-type galaxies

    Systematic variation of the stellar initial mass function with velocity dispersion in early-type galaxies. , keywords =. doi:10.1093/mnrasl/sls014 , archivePrefix =. 1206.1594 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnrasl/sls014

  26. [26]

    Stellar populations in NGC 5128 with the VLT: evidence for recent star formation

    Stellar populations in NGC 5128 with the VLT: Evidence for recent star formation. , keywords =. doi:10.1051/0004-6361:20011315 , archivePrefix =. astro-ph/0109406 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361:20011315

  27. [27]

    Structural Parameters for Globular Clusters in NGC 5128. II. Hubble Space Telescope ACS Imaging and New Clusters. , keywords =. doi:10.1086/507579 , archivePrefix =. astro-ph/0607269 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/507579

  28. [28]

    F., et al., 2006, @doi [ ] 10.1086/498708 , http://adsabs.harvard.edu/abs/2006AJ....131.1163S 131, 1163

    The Two Micron All Sky Survey (2MASS). , keywords =. doi:10.1086/498708 , adsurl =

    work page doi:10.1086/498708

  29. [29]

    , keywords =

    Surface brightness fluctuation spectrum: a new probe of evolved stars in unresolved stellar populations. , keywords =. doi:10.1093/mnras/sty1840 , adsurl =

    work page doi:10.1093/mnras/sty1840

  30. [30]

    Fluctuation Spectroscopy: A New Probe of Old Stellar Populations

    Fluctuation Spectroscopy: A New Probe of Old Stellar Populations. , keywords =. doi:10.1088/0004-637X/797/1/56 , archivePrefix =. 1410.0007 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/797/1/56

  31. [31]

    New Optical and Near-Infrared Surface Brightness Fluctuation Models. II. Young and Intermediate-Age Stellar Populations. , keywords =. doi:10.1086/497591 , archivePrefix =. astro-ph/0509020 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/497591

  32. [32]

    , keywords =

    A New Technique for Measuring Extragalactic Distances. , keywords =. doi:10.1086/114847 , adsurl =

    work page doi:10.1086/114847

  33. [33]

    From the inner Milky Way to Local Volume galaxies: resolved stellar populations with ELT-HARMONI

    From the inner Milky Way to Local Volume galaxies: resolved stellar populations with ELT-HARMONI. arXiv e-prints , keywords =. doi:10.48550/arXiv.1810.04422 , archivePrefix =. 1810.04422 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.1810.04422

  34. [34]

    The TRGB SBF Project. II. Resolving the Virgo Cluster with JWST. , keywords =. doi:10.3847/1538-4357/adb399 , archivePrefix =. 2408.16810 , primaryClass =

    work page doi:10.3847/1538-4357/adb399

  35. [35]

    Integrated J- and H-band spectra of globular clusters in the LMC: implications for stellar population models and galaxy age dating

    Integrated J- and H-band spectra of globular clusters in the LMC: implications for stellar population models and galaxy age dating. , keywords =. doi:10.1051/0004-6361/201218847 , archivePrefix =. 1205.5269 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201218847

  36. [36]

    Carbon stars in the X-shooter Spectral Library. II. Comparison with models. , keywords =. doi:10.1051/0004-6361/201629750 , archivePrefix =. 1702.00819 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201629750

  37. [37]

    , year = 1963, month = jan, volume =

    The A'\^\ 3\ \_\ g\ - X'\^\ 3\ \_\ u\ Band System of the C\_\ 2\ Molecule. , year = 1963, month = jan, volume =. doi:10.1086/147485 , adsurl =

    work page doi:10.1086/147485 1963

  38. [38]

    The Star-Forming Histories of the Nucleus, Bulge, and Inner Disk of NGC 5102: Clues to the Evolution of a Nearby Lenticular Galaxy

    The Star-forming Histories of the Nucleus, Bulge, and Inner Disk of NGC 5102: Clues to the Evolution of a Nearby Lenticular Galaxy. , keywords =. doi:10.1088/0004-637X/799/1/97 , archivePrefix =. 1412.2086 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/799/1/97 2086

  39. [39]

    Galaxies M32 and NGC 5102 Confirm a Near-infrared Spectroscopic Chronometer

    Galaxies M32 and NGC 5102 Confirm a Near-infrared Spectroscopic Chronometer. , keywords =. doi:10.1088/2041-8205/727/1/L15 , archivePrefix =. 1012.2807 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/2041-8205/727/1/l15 2041

  40. [40]

    A., okas E

    Peering through the OH forest: a new technique to remove residual sky features from Sloan Digital Sky Survey spectra. , keywords =. doi:10.1111/j.1365-2966.2005.08844.x , archivePrefix =. astro-ph/0501460 , primaryClass =

    work page doi:10.1111/j.1365-2966.2005.08844.x 2005

  41. [41]

    J., Katz, H., Rey, M

    Nitrogen enhancements 440 Myr after the big bang: supersolar N/O, a tidal disruption event, or a dense stellar cluster in GN-z11?. , keywords =. doi:10.1093/mnras/stad1579 , archivePrefix =. 2302.10142 , primaryClass =

    work page doi:10.1093/mnras/stad1579

  42. [42]

    and Plaza, Antonio and Dobigeon, Nicolas and Parente, Mario and Du, Qian and Gader, Paul and Chanussot, Jocelyn , journal=

    Bioucas-Dias, José M. and Plaza, Antonio and Dobigeon, Nicolas and Parente, Mario and Du, Qian and Gader, Paul and Chanussot, Jocelyn , journal=. Hyperspectral Unmixing Overview: Geometrical, Statistical, and Sparse Regression-Based Approaches , year=

    work page

  43. [43]

    IEEE signal processing magazine , volume=

    Spectral unmixing , author=. IEEE signal processing magazine , volume=. 2002 , publisher=

    work page 2002

  44. [44]

    , keywords =

    Probing cool giants in unresolved galaxies using fluctuation eigenspectra: A demonstration using high-resolution MUSE observations of NGC 5128. , keywords =. doi:10.1093/mnras/stab3415 , archivePrefix =. 2111.09317 , primaryClass =

    work page doi:10.1093/mnras/stab3415

  45. [45]

    A New Chemo-evolutionary Population Synthesis Model for Early-Type Galaxies. II. Observations and Results. , keywords =. doi:10.1086/313008 , archivePrefix =. astro-ph/9701036 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/313008

  46. [46]

    , keywords =

    Comprehensive Stellar Population Models and the Disentanglement of Age and Metallicity Effects. , keywords =. doi:10.1086/192096 , adsurl =

    work page doi:10.1086/192096

  47. [47]

    and Shibahashi , H

    PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code. , keywords =. doi:10.1111/j.1365-2966.2012.21948.x , archivePrefix =. 1208.4498 , primaryClass =

    work page doi:10.1111/j.1365-2966.2012.21948.x 2012

  48. [48]

    , keywords =

    Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud. , keywords =. doi:10.1093/mnras/staa2565 , archivePrefix =. 2008.08595 , primaryClass =

    work page doi:10.1093/mnras/staa2565 2008

  49. [49]

    The Extended IRTF Spectral Library: Expanded coverage in metallicity, temperature, and surface gravity

    The Extended IRTF Spectral Library: Expanded Coverage in Metallicity, Temperature, and Surface Gravity. , keywords =. 2017. doi:10.3847/1538-4365/aa72ed , archivePrefix =. 1705.08906 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4365/aa72ed 2017

  50. [50]

    and Yang , J

    Sánchez-Blázquez, P. and Peletier, R. F. and Jiménez-Vicente, J. and Cardiel, N. and Cenarro, A. J. and Falcón-Barroso, J. and Gorgas, J. and Selam, S. and Vazdekis, A. , title =. Monthly Notices of the Royal Astronomical Society , volume =. 2006 , month =. doi:10.1111/j.1365-2966.2006.10699.x , url =

    work page doi:10.1111/j.1365-2966.2006.10699.x 2006

  51. [51]

    , year = 1955, month = jan, volume =

    The Luminosity Function and Stellar Evolution. , year = 1955, month = jan, volume =. doi:10.1086/145971 , adsurl =

    work page doi:10.1086/145971 1955

  52. [52]

    The Open Journal of Astrophysics , keywords =

    Early Bright Galaxies from Helium Enhancements in High-Redshift Star Clusters. The Open Journal of Astrophysics , keywords =. doi:10.33232/001c.126253 , archivePrefix =. 2410.14846 , primaryClass =

    work page doi:10.33232/001c.126253

  53. [53]

    , keywords =

    Strong CO absorption features in massive ETGs. , keywords =. doi:10.1093/mnras/stac471 , archivePrefix =. 2202.08651 , primaryClass =

    work page doi:10.1093/mnras/stac471

  54. [54]

    The Distance to NGC 5128 (Centaurus A)

    The Distance to NGC 5128 (Centaurus A). , keywords =. doi:10.1071/AS09061 , archivePrefix =. 0911.3180 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1071/as09061

  55. [55]

    Far-Ultraviolet Radiation from Elliptical Galaxies

    Far-Ultraviolet Radiation from Elliptical Galaxies. , keywords =. doi:10.1146/annurev.astro.37.1.603 , archivePrefix =. astro-ph/9906068 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1146/annurev.astro.37.1.603

  56. [56]

    , keywords =

    Puzzling radial gradients of K-band absorption features in the giant elliptical galaxy M87. , keywords =. doi:10.1051/0004-6361/202554315 , archivePrefix =. 2506.05986 , primaryClass =

    work page doi:10.1051/0004-6361/202554315

  57. [57]

    IMF and [Na/Fe] abundance ratios from optical and NIR Spectral Features in Early-type Galaxies

    IMF and [Na/Fe] abundance ratios from optical and NIR spectral features in early-type galaxies. , keywords =. doi:10.1093/mnras/stw2407 , archivePrefix =. 1610.03853 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stw2407

  58. [58]

    The Propagation of Uncertainties in Stellar Population Synthesis Modeling. I. The Relevance of Uncertain Aspects of Stellar Evolution and the Initial Mass Function to the Derived Physical Properties of Galaxies. , keywords =. doi:10.1088/0004-637X/699/1/486 , archivePrefix =. 0809.4261 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/699/1/486

  59. [59]

    Galaxies , keywords =

    Applications of Stellar Population Synthesis in the Distant Universe. Galaxies , keywords =. doi:10.3390/galaxies8010006 , archivePrefix =. 2005.01759 , primaryClass =

    work page doi:10.3390/galaxies8010006 2005

  60. [60]

    The Stellar Spectral Features of Nearby Galaxies in the Near-Infrared: Tracers of Thermally-Pulsing Asymptotic Giant Branch Stars?

    The stellar spectral features of nearby galaxies in the near infrared: tracers of thermally pulsing asymptotic giant branch stars?. , keywords =. doi:10.1093/mnras/stv866 , archivePrefix =. 1504.04218 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stv866

  61. [61]

    Probing Evolutionary Population Synthesis Models in the Near Infrared with Early Type Galaxies

    Probing evolutionary population synthesis models in the near infrared with early-type galaxies. , keywords =. doi:10.1093/mnras/sty515 , archivePrefix =. 1802.08280 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/sty515

  62. [62]

    Comparison of Stellar Population Model Predictions Using Optical and Infrared Spectroscopy

    Comparison of stellar population model predictions using optical and infrared spectroscopy. , keywords =. doi:10.1093/mnras/stx2502 , archivePrefix =. 1709.09300 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stx2502