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arxiv: 2607.05977 · v1 · pith:5IVTGKTL · submitted 2026-07-07 · astro-ph.SR

TESS light curves and surface activity in two low-mass eclipsing binaries: NSVS 01031772 and 2MASS J04100497+2931023

Marek Wolf , Ladislav \v{S}melcer , Hana Ku\v{c}\'akov\'a , Al\v{z}b\v{e}ta Opli\v{s}tilov\'a , Petr Zasche , Franti\v{s}ek B\'ilek , Andrej Mudray , Tom\'a\v{s} Hynek
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Miloslav Zejda Kamil Hornoch
This is my paper

Reviewed by Pith T0 review T1 audit T2 compute T3 formal T4 kernel 2026-07-08 19:27 UTCglm-5.2pith:5IVTGKTLrecord.jsonopen to challenge →

classification astro-ph.SR PACS 97.10.-q97.10.Nf97.10.Gz97.10.Tm
keywords masswerecomponentseclipsingn103binariescurveslight
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The pith

Brown dwarf and red dwarf may orbit two low-mass eclipsing binaries

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

This paper analyzes TESS space photometry and over 200,000 ground-based CCD frames for two short-period, low-mass eclipsing binaries — NSVS 01031772 (N103, two M4 dwarfs) and 2MASS J04100497+2931023 (2M0410, two K5 dwarfs) — to refine the absolute masses and radii of their stellar components and to investigate the cause of their eclipse timing variations. The authors model the observed minus calculated (O-C) eclipse timing residuals as a light-time effect (LITE), the periodic delay caused by the eclipsing pair orbiting the barycenter of a triple system with an unseen companion. For N103, they fit a 19.4-year LITE period and derive a minimum companion mass of roughly 50 Jupiter masses, placing it in the brown dwarf regime. For 2M0410, three full cycles of a 2.1-year LITE are covered, yielding a minimum companion mass of about 0.1 solar masses, consistent with a late-M red dwarf. They also test whether N103 could be a (2+1)+1 quadruple system by adding a fourth body to explain residual timing variations, but N-body integrations show such a configuration is dynamically unstable on short timescales. Separately, the paper characterizes surface magnetic activity: N103 flares at a mean rate of one event per 40 hours with 157 flares detected across 13 TESS sectors, while 2M0410 shows essentially no flares but exhibits persistent starspot modulation requiring a dark spot in the light-curve model. The authors note that the O-C variations, particularly for N103 where the 19-year LITE cycle is only partially covered by the roughly 20-year data baseline, could alternatively arise from magnetically induced period changes rather than a third body, and they acknowledge this ambiguity explicitly.

Core claim

The central claim is that sinusoidal eclipse timing variations in both N103 and 2M0410 can be modeled by the light-time effect, implying unseen tertiary companions: a ~50 Jupiter-mass brown dwarf with a 19.4-year orbit for N103, and a ~0.1 solar-mass red dwarf with a 2.1-year orbit for 2M0410. A secondary finding is that the two astrophysically similar systems display strikingly different magnetic behavior — N103 is flare-active with symmetric light curves, while 2M0410 is flare-quiet but spot-dominated with distorted light curves — suggesting that surface activity manifestations diverge even among comparable low-mass binaries.

What carries the argument

The light-time effect (LITE): when an eclipsing binary orbits a common barycenter with a distant companion, the extra light-travel path periodically delays or advances the observed eclipse times, producing a sinusoidal pattern in the O-C (observed minus calculated) diagram. The amplitude and period of this signal constrain the companion's mass and orbit.

If this is right

  • If the LITE interpretation for N103 is correct, the system hosts one of the few known brown dwarfs orbiting a low-mass eclipsing binary, useful for constraining brown-dwarf formation and cooling models at the stellar/substellar boundary.
  • The 2M0410 companion, with a well-covered 2.1-year orbit and a minimum mass near the hydrogen-burning limit, is a strong candidate for direct detection via high-resolution imaging or radial-velocity follow-up, which would confirm or refute the third-body hypothesis.
  • The contrast in magnetic activity between N103 (flare-rich, spot-poor) and 2M0410 (flare-poor, spot-rich) provides an empirical data point for how tidal locking and inter-binary magnetic field topology may differently manifest in otherwise similar low-mass systems.
  • The instability of the proposed quadruple configuration for N103 demonstrates that dynamical stability testing is essential when fitting multiple LITE signals, and that residual O-C structure should not automatically be attributed to additional bodies.

Load-bearing premise

The paper assumes that the sinusoidal eclipse timing variations are dominated by the light-time effect from an orbiting third body, rather than by magnetic activity cycles in the stellar interiors altering the quadrupole moment and thus the orbital period. For N103, this assumption is especially fragile because the proposed 19.4-year LITE cycle is only partially covered by the available data, and the authors themselves note that an 11-year residual signal could be magnetic in

What would settle it

If future eclipse timing data for N103 fail to follow the predicted downward limb of the 19-year LITE sinusoid, or if the 2.1-year O-C signal in 2M0410 changes shape or amplitude in a way inconsistent with a Keplerian third-body orbit, the LITE interpretation would be undermined. Direct non-detection of the 2M0410 companion via radial velocities or high-contrast imaging at the predicted separation and mass would also challenge the third-body hypothesis for that system.

Figures

Figures reproduced from arXiv: 2607.05977 by Al\v{z}b\v{e}ta Opli\v{s}tilov\'a, Andrej Mudray, Franti\v{s}ek B\'ilek, Hana Ku\v{c}\'akov\'a, Kamil Hornoch, Ladislav \v{S}melcer, Marek Wolf, Miloslav Zejda, Petr Zasche, Tom\'a\v{s} Hynek.

Figure 1
Figure 1. Figure 1: The emission double-peaked hydrogen H𝛼 line profile of N103 obtained at Keck Observatory in June 2011 as a strong indicator of chromospheric activity. at the 4-m Mayall telescope at the Kitt Peak National Obser￾vatory (KPNO). The wavelength coverage of each spectrum is 5700 – 8160 Å, with a resolution power of 18 750. We used this set of precise radial velocities in our subsequent PHOEBE solution. Two spec… view at source ↗
Figure 3
Figure 3. Figure 3: The current 𝑂−𝐶 diagram for the times of minimum of 2M0410. The blue sinusoidal curve represents the LITE with a short period of about 2 years and a semi-amplitude of about 70 sec. The individual primary and secondary minima are denoted by blue circles and orange triangles, resp. TESS minima are groups of points around epochs 1100, 1800, 2200 and 3000. Three orbits of a possible third body are covered. 𝑒3 … view at source ↗
Figure 2
Figure 2. Figure 2: Top: The historical 𝑂−𝐶 diagram for N103 since its discovery in 2005. The individual primary and secondary CCD minima are denoted by blue circles and red triangles, respectively. Larger symbols correspond to the precise CCD measurements, which were used in our calculation of the LITE. The blue sinusoidal curve represents LITE with period of about 19 years and an semi-amplitude about 0.0018 days. The blue d… view at source ↗
Figure 4
Figure 4. Figure 4: Top: Orbits of the possible third and fourth bodies in N103 evolved over the subsequent 500 000 days after 𝑇0 denoted by crosses. Middle: Evolution of eccentricity. Bottom: Evolution of semi-major axis. The system exhibits large am￾plitude variations in orbital parameters. At the beginning, we see angular momentum transfer from the inner orbit to the outer one. The stepwise changes in 𝑒 and 𝑎 indicate ener… view at source ↗
Figure 5
Figure 5. Figure 5: PHOEBE solution of N103 light curves: from up to bottom TESS LC plots in Sectors 48 (red), 53 (blue), 60 (orange) and 74 (green) and their solution (black curves). Binning 300 was used. Individual curves are shifted by 0.1. Symmetric light curves without surface inhomogeneities are visible [PITH_FULL_IMAGE:figures/full_fig_p008_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: The radial velocity curve for N103 obtained by Lopez￾Morales et al. (2006) and our solution in PHOEBE. Primary component as blue dots and curve, the secondary in orange. The 𝛾-velocity (+20.4 km/s) is denoted as a dotted line. Residuals are plotted in bottom panel. did not result in a decrease in the PHOEBE cost function. The final solution of the TESS light and radial velocity curves, compared to the prev… view at source ↗
Figure 9
Figure 9. Figure 9: Example of one prominent eruption on N103 followed by a primary eclipse which was discovered on the light curve obtained at Valašské Meziříčí observatory on October 8, 2021. The amplitude of eruption in filter 𝑅 was 0.41 mag, duration about 18 minutes. See also [PITH_FULL_IMAGE:figures/full_fig_p009_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Phase dependence of eruption activity of N103 detected in 13 TESS sectors during 2019-2024 (top panel) and at Valašské Meziříčí observatory during 2014-2025 (bottom). Significantly fewer eruptions were recognized during both eclipses (red columns). Total number of eruptions is 157 and 34, respectively [PITH_FULL_IMAGE:figures/full_fig_p010_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: Mass-Radius diagram for known low-mass eclipsing binaries (collected by Cruz et al. (2018), gray dots). The blue line is the 5 Gyr isochrone of the standard model from Baraffe et al. (1998). Two red dots denote the position of N103 components, two magenta dots corresponds to 2M0410 components. magnetic loops on both stars could be large enough to reach each other, and therefore the flux tubes can be tempo… view at source ↗
read the original abstract

The VRIC light curves were regularly measured for two eclipsing binaries, NSVS 01031772 and 2MASS J04100497+2931023 as part of our long-term observational project to study low-mass eclipsing binaries with a short orbital period and surface activity. The solution of the TESS light curves in PHOEBE results in a detached configuration. Absolute parameters of all components were improved: for N103: M1 = 0.5475 +/- 0.0035 M\sun, R1 = 0.5297 +/- 0.0035 R\sun, M2 = 0.5038 +/- 0.0040 M\sun, R2 = 0.5217 +/- 0.0035 R\sun, for 2M0410: M1 = 0.639 +/- 0.045 M\sun, R1 = 0.655 +/- 0.035 R\sun, M2 = 0.609 +/- 0.045 M\sun, R2 = 0.631 +/- 0.035 R\sun, where the temperatures of the primary components were adopted according to previous studies. The spectral type of the primary components was confirmed to be M4 and K5, and the mass ratio was derived as q = 0.920 +/- 0.003 or 0.952 +/- 0.010, respectively. We propose the presence of a third body in these systems: in the case of N103, a companion with a minimal mass of 50 MJup, orbiting the eclipsing pair with a period of about 19 years, and in 2M0410 a third body with a minimal mass of about 0.1 M\sun and a short orbital period of about 2.1 years. For N103, the hierarchical structure (2+1)+1 of a possible quadruple system was tested, but its stability was not proven. The characteristics and statistics of the flare events and dark regions on the surface of the components were estimated on the basis of the TESS and our own data. For N103, a mean frequency of flares of one per 40 hours was determined. In the case of 2M0410, practically no flares were detected.

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

4 major / 6 minor

Summary. This paper presents TESS and ground-based photometric observations of two low-mass eclipsing binaries, NSVS 01031772 (N103) and 2MASS J04100497+2931023 (2M0410). The authors derive improved absolute parameters for the components via PHOEBE modeling, analyze eclipse timing variations (ETVs) to infer third-body companions via the light-time effect (LITE), test dynamical stability of a possible quadruple configuration for N103, and characterize flare activity. The dataset is extensive: 453 eclipse times for N103 and 121 for 2M0410, spanning roughly two decades. The PHOEBE solutions and flare statistics appear carefully done. The LITE interpretation, particularly for N103, requires more rigorous justification.

Significance. The paper provides a valuable long-term photometric dataset for two low-mass eclipsing binaries, a class important for testing stellar evolution models. The improved absolute parameters for N103 are consistent with previous work (Lopez-Morales et al. 2006), and the flare frequency analysis (1 per ~40 hours) is a useful contribution. The N-body stability analysis for the proposed quadruple system in N103, performed with the XITAU code, is a commendable effort that conclusively rules out the (2+1)+1 hierarchy. The 2M0410 ETV signal covers three cycles, making its periodicity more secure. However, the central third-body claims, especially for N103, rest on interpretations that are not yet fully substantiated.

major comments (4)
  1. §4.1, Table 3, Fig. 2: The N103 LITE fit has a period of 19.4 ± 1.0 years, but the observational baseline spans only ~20 years (discovery in 2005, data through 2025). This means roughly one full cycle is covered, and the eccentricity was fixed to zero due to insufficient phase coverage. With only one cycle, the sinusoidal fit is not uniquely determined, and the decomposition into a 19-yr LITE plus an 11-yr residual (Fig. 2, bottom panel) is degenerate: the frequency separation between 11-yr and 19-yr signals is poorly resolved over a 20-yr baseline. The authors should explicitly quantify how well-constrained the 19-yr period is given the baseline, and discuss whether alternative single-period or multi-period decompositions are statistically excluded. The current treatment does not demonstrate that the 19-yr LITE interpretation is preferred over a purely magnetic origin for the entire O-C
  2. §4.3: The Applegate (1992) mechanism is dismissed qualitatively with the statement 'Usually, this mechanism cannot contribute significantly to the observed period changes in many eclipsing systems.' No quantitative test is performed. For N103, the observed period change is ΔP = 0.16 s and the LITE semi-amplitude is 153 s. The authors should compute the required quadrupole moment change ΔQ (using the Applegate or Lanza 2020 formalism) for the observed O-C amplitude and compare it to the available magnetic energy budget of the M4 components. This is a standard diagnostic and is necessary to distinguish LITE from magnetic modulation, particularly given that the 11-yr residual is already attributed to magnetic activity.
  3. §5, Table 5: The mass ratio for 2M0410 derived here (q = 0.95 ± 0.12) differs dramatically from Meng et al. (2021) (q = 1.79 ± 0.01). The paper states 'we cannot confirm the previous results' but does not adequately explain the discrepancy. Since the third-body minimal mass M3,min depends on M1+M2 (Table 3), this discrepancy directly affects the claimed ~0.1 M_sun companion. The RV curve from Meng et al. is described as 'partially covered' (§3.3, Fig. 8), which may explain the difference, but the authors should explicitly discuss whether their q is reliable given the incomplete phase coverage, and how the large uncertainty (±0.12) propagates into M3,min.
  4. §7, Conclusions: The statement 'In our case, N103 is a pair of normal red dwarfs, where the observed period changes cannot be explained by a multiple system' appears to contradict the paper's central claim that N103 hosts a third body detected via LITE. If this sentence refers only to the 11-yr residual (i.e., a fourth body is excluded), it should be reworded for clarity. As written, it undermines the LITE interpretation without explanation.
minor comments (6)
  1. §4.1: The coplanar assumption (i3 ≈ i) is stated without justification. Since M3,min scales as sin^{-3}(i3), even moderate misalignment would significantly change the mass estimate. A brief discussion of this assumption's impact would be appropriate.
  2. Table 3: The LITE parameters list internal 'fit errors' in parentheses, but it is unclear whether these account for correlations between A3 and P3, which are typically strong in LITE fits. Clarification on the error estimation method would help.
  3. Fig. 2: The caption mentions a 'blue dotted curve' representing the combined LITE + next variation, but the distinction between the solid and dotted curves in the top panel is difficult to discern. Consider using different line styles or colors.
  4. §6, Table 8: Entry 8 lists a flare with amplitude 0.03 mag in clear filter and duration 16.7 min, but the rise time is listed as 0.7 min with 'Rise' instead of 'Max' in the Event column. Please clarify whether this is a partial flare detection.
  5. Table 6: The PHOEBE cost function values vary substantially across sectors (350–785). A brief comment on whether this indicates sector-dependent spot model quality would be useful.
  6. §2.2: The LAMOST radial velocities for 2M0410 (–17.0 and +10.4 km/s) are mentioned but not used in the analysis. Clarify why these were excluded.

Simulated Author's Rebuttal

4 responses · 0 unresolved

We thank the referee for a careful and constructive report. The comments are well-taken and we address each point below. In summary: (1) we will add a quantitative discussion of the period constraints and alternative decompositions for the N103 O-C diagram; (2) we will perform a quantitative Applegate/Lanza test for N103; (3) we will expand the discussion of the 2M0410 mass ratio discrepancy and its propagation into M3,min; and (4) we will reword the contradictory sentence in the Conclusions. All four points require revision.

read point-by-point responses

  1. Referee: §4.1, Table 3, Fig. 2: The N103 LITE fit has a period of 19.4 ± 1.0 years, but the observational baseline spans only ~20 years. With only one cycle, the sinusoidal fit is not uniquely determined, and the decomposition into a 19-yr LITE plus an 11-yr residual is degenerate. The authors should quantify how well-constrained the 19-yr period is and discuss whether alternative decompositions are statistically excluded. The current treatment does not demonstrate that the 19-yr LITE interpretation is preferred over a purely magnetic origin.

    Authors: The referee is correct that the 19-yr period is only marginally resolved given the ~20-yr baseline, and we agree that the current manuscript does not adequately address this limitation. We will revise the manuscript as follows. First, we will explicitly state that the observational baseline covers approximately one full cycle of the proposed LITE, which means the period is poorly constrained — consistent with the formal uncertainty of ±1.0 yr but with significant covariance between period, amplitude, and phase that the formal error does not capture. Second, we will compute and report the residual sum of squares for alternative single-sinusoid fits (e.g., periods in the range 10–25 yr) and for two-period decompositions with different period combinations, to show quantitatively which decompositions are statistically excluded. Third, we will add an explicit statement that the 19-yr LITE interpretation is a working hypothesis rather than a uniquely determined solution, and that a purely magnetic origin for the full O-C signal cannot be excluded on the basis of the ETV data alone. We note that the 11-yr residual period was identified only after subtracting the 19-yr LITE, and we agree that the frequency separation between 11 and 19 yr is poorly resolved over a 20-yr baseline. We will state this degeneracy explicitly. The dynamical stability analysis in Section 4.2, which rules out the (2+1)+1 quadruple hierarchy, is independent of this decomposition issue and remains valid. revision: yes

  2. Referee: §4.3: The Applegate (1992) mechanism is dismissed qualitatively. No quantitative test is performed. The authors should compute the required quadrupole moment change ΔQ and compare it to the available magnetic energy budget of the M4 components.

    Authors: We agree that a quantitative Applegate test is necessary and should have been included. We will compute the required ΔQ using the Applegate (1992) formalism for the observed O-C amplitude (153 s for the 19-yr LITE component, and ~60 s for the 11-yr residual) and compare it to the available magnetic energy budget of the M4 components. We will also apply the Lanza (2020) reformulation, which provides a more physically motivated framework for convective-envelope stars. Specifically, we will compute the required luminosity modulation and surface magnetic field strength, and compare these to observationally plausible values for M4 dwarfs. If the required ΔQ exceeds what is physically plausible for the M4 components, this strengthens the LITE interpretation; if not, we will state that both mechanisms remain viable. We will present these calculations in a revised Section 4.3 with the quantitative results tabulated. revision: yes

  3. Referee: §5, Table 5: The mass ratio for 2M0410 derived here (q = 0.95 ± 0.12) differs dramatically from Meng et al. (2021) (q = 1.79 ± 0.01). The paper does not adequately explain the discrepancy. Since M3,min depends on M1+M2, this discrepancy directly affects the claimed ~0.1 M_sun companion. The authors should discuss whether their q is reliable given incomplete phase coverage and how the large uncertainty propagates into M3,min.

    Authors: The referee is correct that this discrepancy requires more thorough discussion. The root cause is that the LAMOST radial velocities from Meng et al. (2021) cover only a portion of the orbital phase (as shown in Figure 8 and noted in Section 3.3), which limits the reliability of the mass ratio derived from the RV curve. Our PHOEBE solution uses these same RVs together with the TESS light curves, but the incomplete phase coverage means the mass ratio is poorly constrained — hence the large uncertainty of ±0.12. We will add a detailed discussion of this issue, explicitly stating that our q = 0.95 ± 0.12 should be considered tentative pending complete phase coverage of the RV curve, and that the discrepancy with Meng et al. (2021) likely arises from the different weighting of the limited RV data in the PHOEBE fit versus their independent analysis. Regarding the propagation into M3,min: since M3,min depends on (M1+M2)^(2/3) in the LITE mass function, we will compute and report the range of M3,min implied by the ±0.12 uncertainty in q. We will also note that complete spectroscopic coverage is needed to resolve this discrepancy definitively, as we already state in the Conclusions. revision: yes

  4. Referee: §7, Conclusions: The statement 'In our case, N103 is a pair of normal red dwarfs, where the observed period changes cannot be explained by a multiple system' appears to contradict the paper's central claim that N103 hosts a third body detected via LITE.

    Authors: We agree that this sentence is confusingly worded and appears to contradict our own LITE claim. The intended meaning is that the 11-yr residual in the O-C diagram — after subtracting the 19-yr LITE — cannot be explained by a fourth body (as demonstrated by the dynamical instability analysis in Section 4.2), and is instead likely magnetic in origin. The sentence was meant to echo the findings of Pulley et al. (2025) and Yates et al. (2026) regarding magnetic mechanisms, but as written it undermines the LITE interpretation. We will reword this passage to make clear that (a) the 19-yr LITE signal is attributed to a third body, (b) the 11-yr residual is attributed to magnetic activity or an unknown mechanism, and (c) a fourth body is excluded by the dynamical stability analysis. We thank the referee for identifying this inconsistency. revision: yes

Circularity Check

0 steps flagged

No significant circularity; standard LITE methodology with minor self-citation for prior detection

full rationale

The paper follows standard observational astronomy methodology. The LITE analysis fits O-C diagram parameters (A3, P3) and then computes the mass function f(M3) and minimal mass M3,min from those fitted parameters. This is the standard Irwin (1952) LITE pipeline — the mass is explicitly presented as a derived estimate from the fit, not as an independent first-principles prediction. The paper does not claim the third-body masses are predicted independently of the O-C fit. The self-citations (Wolf et al. 2012 for the initial N103 LITE proposal; Šmelcer et al. 2023 for LITE equations) are methodological references and updates with extended data, not load-bearing theorems that would make the argument circular. The PHOEBE solutions use externally obtained radial velocities (Lopez-Morales et al. 2006; Meng et al. 2021) and fixed primary temperatures from prior studies as inputs — standard practice, not circular. The dynamical stability test (Section 4.2) uses the XITAU code (Brož 2017) with the fitted orbital parameters, which is an independent numerical test, not a definitional identity. The Applegate mechanism is mentioned but not quantitatively tested — this is a correctness/robustness concern, not a circularity issue. No step in the derivation chain reduces to its inputs by construction.

Axiom & Free-Parameter Ledger

9 free parameters · 5 axioms · 2 invented entities

The free parameters are standard fitted quantities in LITE and PHOEBE analyses. The key ad hoc assumption is coplanarity for the third body, which directly affects the minimal mass estimate. The invented entities (the two companions) lack independent confirmation and rest on the assumption that LITE dominates over magnetic mechanisms.

free parameters (9)
  • A3 (N103) = 0.00177 days
    Semi-amplitude of the LITE curve, fitted to the O-C diagram.
  • P3 (N103) = 7090 days
    Orbital period of the third body, fitted to the O-C diagram.
  • e3 (N103) = 0 (fixed)
    Eccentricity of the third body, fixed to zero due to insufficient phase coverage.
  • A3 (2M0410) = 0.00076 days
    Semi-amplitude of the LITE curve, fitted to the O-C diagram.
  • P3 (2M0410) = 771 days
    Orbital period of the third body, fitted to the O-C diagram.
  • e3 (2M0410) = 0.035
    Eccentricity of the third body, fitted to the O-C diagram.
  • Spot parameters (2M0410) = varies by sector
    Colatitude, longitude, spot radius, and temperature factor for the dark spot on the secondary, fitted per TESS sector. Spot temperature factor assumed ~0.95.
  • T1 (N103) = 3615 K (fixed)
    Primary temperature fixed from Lopez-Morales et al. (2006).
  • T1 (2M0410) = 4500 K (fixed)
    Primary temperature fixed from Meng et al. (2021).
axioms (5)
  • domain assumption The light-time effect (LITE) is the dominant cause of the observed O-C variations.
    Invoked in Section 4.1 to derive third-body parameters. The paper acknowledges magnetic activity as an alternative but proceeds with LITE as the primary interpretation.
  • ad hoc to paper The third-body orbit is coplanar with the eclipsing binary (i3 ≈ i).
    Stated in Section 4.1 to compute minimal masses M3,min. No independent evidence for coplanarity is provided.
  • domain assumption Synchronous rotation (F1 = F2 = 1) and circular orbits (e = 0) for the binary.
    Adopted in the PHOEBE solution (Section 5). Standard for short-period detached binaries but an assumption nonetheless.
  • standard math Bolometric albedos A = 0.5 and gravity darkening g = 0.32 for convective envelopes.
    Standard values from Lucy (1968), adopted in Section 5.
  • domain assumption Spot/star temperature ratio ≈ 0.95.
    Assumed in Section 5 for 2M0410 spot modeling because effective temperature and radius of a spot are strongly correlated.
invented entities (2)
  • Third body in N103 (~50 M_Jup brown dwarf) no independent evidence
    purpose: To explain the 19.4-year periodic O-C variation via LITE.
    No direct detection (imaging or spectroscopic); existence inferred solely from O-C diagram which is also plausibly explained by magnetic activity. The paper provides no falsifiable prediction beyond the LITE fit itself.
  • Third body in 2M0410 (~0.1 M_sun red dwarf) no independent evidence
    purpose: To explain the 2.1-year periodic O-C variation via LITE.
    No direct detection; inferred from O-C variations. RUWE ~1.5 for both systems is consistent with binarity but does not confirm this specific companion.

pith-pipeline@v1.1.0-glm · 32226 in / 3357 out tokens · 729271 ms · 2026-07-08T19:27:11.012220+00:00 · methodology

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