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REVIEW 4 major objections 5 minor 17 references

Asteroseismic mass and radius of the naked-eye red giant HD145250

T0 review · 4 major / 5 minor · reviewed 2026-08-07 · deepseek-v4-flash

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Pith's one-line read A naked-eye red giant's first asteroseismic analysis yields a mass near 1.4 solar masses and a radius near 16 solar radii.

desk verdict First seismic look at a bright nearby red giant yields a credible luminosity-based mass but a radius that leans on a single-sector Δν with unresolved modes; worth refereeing with a robustness request. read the letter →

arxiv 2505.20542 v1 pith:D3WZLHUK submitted 2025-05-26 astro-ph.SR

László Molnár , Klára Lelkes This is my paper · ORCID
classification astro-ph.SR
keywords asteroseismologyredgiantTESSscalingrelationssolar-likeoscillationsstellarmassradiusHD145250
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

This paper establishes the first asteroseismic mass and radius for HD145250, a bright naked-eye red giant within 100 pc that was not covered by earlier survey campaigns. Using a single sector of TESS photometry, the authors detect the star's solar-like oscillations and derive the frequency of maximum oscillation amplitude $\nu_{\max}$ and the large frequency separation $\Delta\nu$. From asteroseismic scaling relations they obtain a mass near $1.4\,M_\odot$ and a radius near $16\,R_\odot$, placing the star on the ascending red giant branch in the hydrogen-shell-burning phase. The result matters because it extends asteroseismic characterization to a nearby, well-known star and shows that useful global seismic quantities can be extracted even when individual modes are not resolved over one TESS sector.

What carries the argument

The load-bearing mechanism is the asteroseismic scaling relations of Kjeldsen and Bedding (1995), as calibrated by Huber et al. (2011), which connect the measured frequency of maximum oscillation amplitude $\nu_{\max}$ and the large frequency separation $\Delta\nu$ to stellar mass, radius, and effective temperature relative to the Sun. Equations (1)--(3) of the paper compute a $\Delta\nu$-based mass, a luminosity-based mass, and a radius from these quantities, with correction factors $f_{\nu_{\max}}=1$ and $f_{\Delta\nu}=0.97$. The argument also depends on adopted spectroscopic parameters, a Gaia EDR3 distance, and a Gaia DR3-based bolometric correction to fix the luminosity.

What would settle it

Observe HD145250 with TESS over several sectors or with a longer-baseline ground-based campaign so that individual oscillation modes are resolved; an independent $\Delta\nu$ differing from $2.53\,\mu$Hz by more than the quoted uncertainty would shift the $\Delta\nu$-based mass by roughly four times the fractional change, and a direct interferometric radius could check the $16\,R_\odot$ result.

Watch

Extended reading notes

Core claim

The paper's central claim is that HD145250, a naked-eye red giant at about 87 pc, is a hydrogen-shell-burning star ascending the red giant branch, with asteroseismic mass $\sim 1.4\,M_\odot$ and radius $\sim 16\,R_\odot$. The authors measure the global oscillation quantities $\nu_{\max} = 21.4 \pm 1.0\,\mu$Hz and $\Delta\nu = 2.53 \pm 0.20\,\mu$Hz from a single 27-day TESS sector, then apply asteroseismic scaling relations calibrated to the Sun. The $\Delta\nu$-based mass relation gives $1.67 \pm 0.58\,M_\odot$; the luminosity-based relation gives $1.38 \pm 0.09\,M_\odot$, and the radius relation gives $16.5 \pm 2.7\,R_\odot$. The paper argues that these values agree with published non-seismic estimates from evolutionary-model comparisons, and interprets the star as outside the red clump and therefore not yet burning helium in its core.

Load-bearing premise

The load-bearing premise is that the large frequency separation $\Delta\nu = 2.53 \pm 0.20\,\mu$Hz measured from one unresolved TESS sector is accurate, together with the assumed correction factor $f_{\Delta\nu}=0.97$; because the mass from the $\Delta\nu$-based relation scales as $\Delta\nu^{-4}$, even a modest bias would change the inferred mass noticeably.

Editorial extensions

If this is right

  • HD145250 is confirmed as a low-mass red giant ascending the red giant branch, more massive than the Sun and outside the helium-burning red clump.
  • The star becomes one of the nearest bright giants with asteroseismic mass and radius estimates, available for tests against interferometry and binarity.
  • A single TESS sector is sufficient to detect the oscillation power excess and produce global seismic quantities for such a star, even when individual modes are unresolved.
  • The agreement between the seismic and non-seismic mass and radius estimates supports the use of the adopted scaling relations and correction factors at these low frequencies.
  • The tension between the $\Delta\nu$-based and luminosity-based masses points to either an underestimated $\Delta\nu$ uncertainty or the possible faint companion, motivating future observations.

Reading between the lines

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

  • If a longer TESS baseline resolves the individual modes, an independent $\Delta\nu$ would either confirm $2.53\,\mu$Hz or shift the mass substantially, since the $\Delta\nu$-based mass scales as $\Delta\nu^{-4}$.
  • Because the star is only 87 pc away, a direct interferometric radius measurement could check the $16\,R_\odot$ prediction without relying on the scaling relations.
  • The suspected faint companion from the proper-motion anomaly could be tested by radial-velocity monitoring or high-contrast imaging; if present, it may also affect the photometric luminosity used in the luminosity-based mass.
  • The same single-sector approach could be applied to other bright nearby giants that lack dedicated survey coverage, producing a quick census of masses and radii from archival TESS data.
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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 / 5 minor

Summary. This paper presents the first asteroseismic analysis of the naked-eye red giant HD145250 using 2-minute TESS photometry from a single sector (Sector 65). The authors measure the frequency of maximum power, νmax = 21.4 ± 1.0 μHz, and the large frequency separation, Δν = 2.53 ± 0.20 μHz, with individual oscillation modes unresolved over the ~27-day sector. Using standard asteroseismic scaling relations with literature values for effective temperature, luminosity, and solar reference values, they derive a mass from the Δν-based relation of 1.67 ± 0.58 M☉ (Eq. 1) and from the luminosity-based relation of 1.38 ± 0.09 M☉ (Eq. 2), adopting the latter as the headline mass of ~1.4 M☉. The radius from Eq. (3) is 16.5 ± 2.7 R☉. These values are compared with published model-based estimates, and the paper concludes that HD145250 is an H-shell burning red giant ascending the red giant branch.

Significance. If the central result holds, this is a modest but useful addition: it adds a bright, nearby, naked-eye target to the asteroseismic sample and demonstrates that useful global seismic parameters can be extracted from a single TESS sector even when modes are unresolved. The paper is honest about the two mass estimates and does not introduce fitted parameters; the correction factors are taken from the literature. The main value is the cross-check between asteroseismic and model-based masses, and the potential of this star to serve as a calibration anchor. However, the significance is limited by the reliance on a single-sector Δν measurement, which drives the radius and the uncertain Δν-based mass, and by the unresolved tension with the Fouesneau et al. luminosity.

major comments (4)
  1. [Section 2, Eq. (3)] The headline radius of 16.5 ± 2.7 R☉ rests entirely on the single-sector Δν = 2.53 ± 0.20 μHz, and the authors state in Section 2 and Figure 1 that individual modes are unresolved over the 27-day sector. The quoted uncertainty is statistical only and does not account for systematics from unresolved modes, from the adopted fΔν = 0.97 correction, or from the choice of background model. A 5% bias in Δν changes the radius by about 10% and the Eq. (1) mass by about 20%. The paper should provide a robustness test, for example by recomputing the radius and mass for Δν values spanning the plausible systematic range, or by deriving an independent Δν estimate from Sector 12 even if it is noisier. Without such a test, the radius claim is more fragile than the abstract implies.
  2. [Section 2, Sector 12 exclusion] The decision not to use Sector 12 is described only as 'That sector gave a much poorer fit which we decided not to use in our analysis.' This is a post-hoc exclusion, and the paper does not quantify how poor the fit was, does not report the fitted νmax and Δν from Sector 12, and does not show the Sector 12 power spectrum in Figure 1 (the red bands are only for S65). Since the two sectors were observed in 2019 and 2023, a comparison between them would be an important consistency check for the Δν measurement. The authors should report the Sector 12 values, even if unusable, and state an explicit criterion for inclusion or exclusion.
  3. [Section 3, comparison with Fouesneau et al.] The paper quotes R = 17.48 ± 0.37 R☉ at L = 118.6 ± 1.8 L☉ from Fouesneau et al. (2023) and says this is 'significantly higher than our result,' but the discrepancy is not discussed further. Since the abstract claims agreement with published non-seismic estimates, this one counterexample needs a quantitative treatment. Is the luminosity difference due to the bolometric correction, extinction, the adopted distance, or a different Teff? Could the discrepancy point to a problem with the assumed fΔν or with the scaling relation itself? The authors should either reconcile the values or clearly state that one of the literature values is preferred and why.
  4. [Section 2, error propagation] The quoted uncertainties on mass and radius appear to propagate only the statistical errors on νmax, Δν, Teff, and L, but the paper does not state the propagation formula or the uncertainty contributions from the correction factors fνmax and fΔν. The adopted fΔν = 0.97 is taken from a model-based figure in Sharma et al. (2016) and its uncertainty is unknown. Because Eq. (1) scales as fΔν^{-4} and Eq. (3) as fΔν^{-2}, an error in fΔν of even 0.02 changes the mass by ~8% and the radius by ~4%. Please list all uncertainty contributions explicitly, including the systematic uncertainty in νmax from unresolved modes.
minor comments (5)
  1. [Section 1, Introduction] The sentence 'it has not included in any TESS surveys' is ungrammatical; it should read 'it has not been included in any TESS surveys' or 'it was not included in any TESS surveys.'
  2. [Figure 1] The red bands in Figure 1 indicate νmax values determined for S65 only. The caption should state this explicitly and, if possible, mark the expected νmax range for Sector 12 as well, so the reader can see why the Sector 12 fit was poor.
  3. [Section 2, luminosity calculation] The uncertainty on the luminosity (86.191 ± 2.097 L☉) appears very small relative to the uncertainties in the bolometric correction, the assumed zero extinction, and the 0.01 mag systematic. Please describe the full error budget for Lbol, including the covariance between the distance and the G-band magnitude.
  4. [Section 2, clump classification] The statement that the star is 'close to, but outside of the He-burning red clump' is not quantitatively supported. A reference to a specific evolutionary-track or clump-boundary calculation, or a position on a Teff–log g diagram, would strengthen this assumption.
  5. [Section 3, Eq. (2)] The mass from Eq. (2), 1.38 ± 0.09 M☉, has a smaller relative uncertainty than the luminosity (2.4% vs. 2.4% on L, but the Eq. (2) mass also depends on Teff to the -3.5 power). Please check the error propagation for this value; it may be underestimated if the Teff uncertainty is not fully included.

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity: the scaling-relation inputs are external measurements, no parameters are fitted to the target, and external model-based comparisons anchor the result.

full rationale

The derivation chain is self-contained and non-circular. The paper measures global asteroseismic quantities (νmax = 21.4 ± 1.0 μHz, Δν = 2.53 ± 0.20 μHz) from TESS photometry and then applies standard asteroseismic scaling relations (Eqs. 1–3) with solar references and correction factors taken from the literature (fνmax = 1 from Reyes et al. 2025; fΔν = 0.97 from Sharma et al. 2016), rather than fitting any parameter to the target star. The headline mass of ~1.4 M⊙ comes from Eq. (2), which uses independently determined luminosity and effective temperature and does not use Δν at all; the radius of ~16 R⊙ comes from Eq. (3), which uses the measured νmax and Δν. No quantity used in the equations is defined in terms of the mass or radius being predicted, and no fitted input is renamed as a prediction. The paper also compares its results against external, non-seismic estimates from stellar models (Charbonnel et al. 2020; Andrae et al. 2018; Fouesneau et al. 2023), providing independent anchors. The noted limitations—unresolved modes in a single sector, the adopted fΔν correction, and the decision not to use Sector 12—are data-quality and systematic-uncertainty concerns, not circularity; they do not make the result equivalent to its inputs by construction. There are no load-bearing self-citations and no uniqueness arguments imported from the authors' own prior work.

Assumptions & free parameters 2 free parameters · 4 assumptions · 0 invented entities

The analysis depends on standard, adopted scaling-relation corrections and several domain assumptions about the star's evolutionary state, singlehood, and extinction. No new physical entities are introduced.

free parameters (2)
  • f_nu_max correction factor = 1.0
    Adopted from Reyes et al. (2025); scales the solar scaling relation for the frequency of maximum power. Chosen from literature, not fitted to this star.
  • f_Delta_nu correction factor = 0.97
    Adopted from Sharma et al. (2016); corrects the large frequency separation scaling for red giants. Not verified for this specific star's mass and metallicity.
assumptions (4)
  • domain assumption TESS photometry and pySYD correctly measure the global asteroseismic parameters nu_max and Delta_nu for HD145250.
    The power excess is assumed to be solar-like oscillations, and the single-sector data are sufficient to determine the global parameters despite unresolved modes (Section 2, Fig. 1).
  • domain assumption Scaling relations (Eqs. 1-3) are valid for this star.
    The asteroseismic scaling relations are assumed to hold for HD145250, with the adopted correction factors and solar reference values (Section 2).
  • domain assumption The star is a single, H-shell burning red giant; no significant companion light contribution.
    Based on Eggleton & Tokovinin (2008) for singlehood, but Kervella et al. (2019) suggest a possible faint companion; luminosity is calculated assuming all observed flux is from the primary (Section 2).
  • domain assumption No interstellar extinction toward HD145250.
    The star is nearby (86.7 pc); a 0.01 mag uncertainty is added to account for potential extinction (Section 2).

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Cite this review

Pith. "Pith review of Asteroseismic mass and radius of the naked-eye red giant HD145250." pith.science (2026). https://pith.science/paper/D3WZLHUK

@misc{pith2026250520542,
  author       = {Pith},
  title        = {Pith review of: Asteroseismic mass and radius of the naked-eye red giant HD145250},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/D3WZLHUK}},
  note         = {Machine review of arXiv:2505.20542}
}
abstract

We present the first asteroseismic analysis of the bright, nearby red giant star, HD145250. We calculate the global seismic quantities of the star from single-sector, 2-minute TESS photometry, and determine its mass and radius to be ~1.4 M$_\odot$ and ~16 R$_\odot$ using asteroseismic scaling relations. Our values agree with published non-seismic mass and radius estimates based on comparisons with stellar evolutionary models.

Figures

Figures reproduced from arXiv: 2505.20542 by the authors.

Figure 1
Figure 1. Top: TESS 2-minute cadence photometry of HD145250. Middle: power density spectra of the light curves. Bottom: oscillation signals in the data after removal of the granulation background. Red bands indicate νmax values determined for S65. on the HRD to stellar evolutionary tracks. They found a mass of 1.5 +1.0 −0.4 M⊙, which agrees with our result. The seismic stellar radius derived from equation (3) is R = 16.5±2.7 … view at source ↗

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Reference graph

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