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REVIEW 3 major objections 3 minor 22 references

Comet 289P/Blanpain: Near-Perihelion Activity and the Phoenicids

T0 review · 3 major / 3 minor · reviewed 2026-08-12 · deepseek-v4-flash

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Pith's one-line read Comet 289P/Blanpain is a remnant of a larger body that shattered between 1743 and 1819, not the source of the Phoenicid stream today.

desk verdict New NEOWISE near-perihelion photometry of 289P is worth having, but the stream-mass argument has a real time-integration error and the 'smallest active fraction' headline is inherited from an assumed ice patch radius, not measured. read the letter →

arxiv 2411.13501 v1 pith:GEGDUGX4 submitted 2024-11-20 astro-ph.EP

Toshihiro Kasuga This is my paper · ORCID
classification astro-ph.EP
keywords comet289P/BlanpainPhoenicidmeteoroidstreamJupiter-familydustproductionraterotationaldisruptionfractionalactiveareasmall-sourceapproximationnear-infraredobservations
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

Comet 289P/Blanpain, the parent body of the Phoenicid meteor shower, was observed near perihelion in two infrared bandpasses to test whether its current outgassing can explain the meteoroid stream that flared in 1956. The paper finds that the comet releases only about $0.01$--$0.02$ kg s$^{-1}$ of dust, with a fractional active area smaller than any previously reported for a Jupiter-family comet. Even when the dust size distribution is stretched to favor large, mass-carrying meteoroids, steady mass loss over the stream's roughly 300-year dynamical age falls an order of magnitude short of the estimated Phoenicid stream mass. The paper concludes that the stream required an additional mass supply, most plausibly the rapid rotational destruction of a sub-kilometer precursor sometime between 1743 and 1819, leaving 289P as a remnant rather than the active source. This matters because it turns a small, nearly dormant comet into a visible record of how sub-kilometer comets can break apart.

What carries the argument

The load-bearing object is the small-source approximation (SSA) model, which treats all observed activity as sublimation from a single small patch of water ice on the nucleus rather than from the whole surface. A radius $r_s \simeq 2$ m for that patch is not measured in the new data; it is carried over from the 1956 Phoenicid analysis, which combined eyewitness meteor magnitudes with dust-trail dynamics to infer millimeter-scale meteoroids ejected at about 0.5 m s$^{-1}$. That $r_s$ enters the ejecta equations and, through $f_A = r_s^2/(4 r_n^2)$, fixes the headline fractional active area once the adopted nucleus radius $r_n = 160 \pm 40$ m is inserted. The SSA model also yields the low dust ejection speeds used to argue that dust is lifted by weak gas drag, and it sets the dust-to-gas ratio $2 \le f_{dg} \le 6$ that converts measured dust rates into active-area fractions.

What would settle it

A decisive observation would be resolved imaging of 289P's nucleus and inner coma during a close perihelion passage, at scales of a few kilometers per pixel or better, to see whether the coma is produced by a compact active spot and to measure the actual size of the active region. If the true active patch is tens of meters, or if ejection velocities are far above the small-source values, the dust production rates could rise enough to close the gap to the stream mass. A second check would be a dynamical search for fragments or a debris trail matching ejection dates between 1743 and 1819.

Watch

Extended reading notes

Core claim

The central claim is that today's 289P is a leftover fragment, not the maker of the Phoenicid stream. The argument is built from infrared photometry at 3.4 and 4.6 micrometers taken on 2019 October 30 and 2020 January 11/12, which gives ejected dust masses of $4100 \pm 200$ kg and $1700 \pm 200$ kg, dust production rates of $0.01$--$0.02$ kg s$^{-1}$, and a dust-to-gas ratio between 2 and 6. These numbers, combined with a modeled sublimating ice patch about 2 m in radius inherited from 1956 Phoenicid meteoroid constraints, yield a fractional active area $f_A = 3.8 \pm 1.9 \times 10^{-5}$, the smallest yet reported for an active Jupiter-family comet, and a perihelion-normalized nongravitational acceleration about an order of magnitude below the trend of well-studied comets. The absence of a 4.6 micrometer excess indicates negligible CO$_2$ and CO. Since even favorable particle-size assumptions give only about $1.9 \times 10^8$ kg of dust over 300 years, compared with a stream mass plausibly in the range $4 \times 10^9$ to $10^{11}$ kg, the paper concludes that steady sublimation cannot supply the Phoenicids and that the required mass came from a disintegration event, probably rotational destruction of a sub-km precursor in 1743--1819. A possible 8.85 hour rotation period is reported but explicitly flagged as needing verification because its periodogram significance is only about 30 percent.

Load-bearing premise

The argument assumes that 289P's present activity is described by the small-source approximation with an ice-patch radius of about 2 m inherited from the 1956 Phoenicid meteoroid sizes and velocities; if the active area is actually much larger or the activity is not patch-like, the derived fractional active area and the dust production rates lose their footing, and with them the mass-budget comparison.

Editorial extensions

If this is right

  • 289P's current steady-state mass loss cannot supply the Phoenicid stream within its roughly 300-year dynamical age, even under favorable particle size distributions.
  • The required stream mass implies that a precursor body roughly 170 m in radius, or a 10 m-thick surface shell of the current nucleus, must have been shed sometime between 1743 and 1819.
  • Because the comet shows no 4.6 micrometer excess, CO$_2$ and CO are essentially absent, leaving water ice as the only plausible driver of its weak activity.
  • A sub-kilometer comet can look nearly dormant yet still show measurable nongravitational acceleration and a possible rotation near 8.85 hours, although the period is not secure.
  • The fractional active area of about $4 \times 10^{-5}$ places 289P at the extreme low end among Jupiter-family comets, comparable only to the dormant comet 169P.

Reading between the lines

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

  • If the rotational-destruction picture is right, a substantial part of the Phoenicid stream may consist of precursor fragments rather than gas-lofted dust, which could make the meteoroids structurally different, for example more friable, from those of actively sublimating comets.
  • The same logic could apply to other small, low-activity Jupiter-family comets that parent young meteor streams: their current dust production might systematically underestimate their past stream-building capacity by an order of magnitude or more.
  • A testable prediction is that the Phoenicid stream should contain an overabundance of large, millimeter-to-decimeter fragments compared with streams supplied by steady sublimation, because breakup ejects material at roughly escape speed rather than at gas-drag speeds.
  • The reported 8.85 hour rotation period, if confirmed by higher-signal observations, would imply a critical bulk density above roughly 1500 kg m$^{-3}$ for an elongated nucleus, which is unusually high for a cometary body and worth checking.
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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

3 major / 3 minor

Summary. This paper presents NEOWISE W1/W2 photometry of comet 289P/Blanpain at two epochs near its 2019/2020 perihelion, and from these data derives ejected dust masses, dust production rates, fractional active area, a candidate rotation period, absence of CO2/CO emission, and a perihelion-normalized nongravitational acceleration. The central claim is that current steady mass loss from 289P is an order of magnitude too small to produce the Phoenicid meteoroid stream within its ~300 yr dynamical lifetime, requiring an impulsive mass supply, most plausibly rotational destruction of a ~170 m precursor between 1743 and 1819. The observational data reduction and several derived quantities are useful, but the stream-mass argument in Section 5.1.1 and the fractional-active-area result in Section 4.1 contain internal inconsistencies that materially affect the paper's headline conclusions.

Significance. If established, the conclusion that 289P is a remnant of a larger, rotationally disrupted body rather than the current source of the Phoenicid stream would be an important contribution to our understanding of sub-km Jupiter-family comets and meteoroid stream formation. The NEOWISE photometry, the W2-based gas limit, and the nongravitational acceleration analysis are potentially valuable observational results. However, the paper as written overstates what the data demonstrate: the smallest-active-area claim is an algebraic consequence of adopted model parameters rather than a new measurement, and the steady-stream-mass estimate omits the active-arc duration by a factor of 15-25. These issues do not destroy the value of the observations, but they require a substantial revision of the paper's quantitative conclusions and abstract.

major comments (3)
  1. [§5.1.1, Eq. (13)] Equation (13) multiplies the instantaneous aperture dust mass, (4/3)ρd Cd \bar{a}, by Norb. Because Cd is the cross-section measured in the photometric aperture at one epoch, this aperture mass equals Qdust × τ, where τ = ρ/vd ≈ 4 d is the residence time of dust in the aperture. The total mass ejected per perihelion passage is instead Qdust × T_active, with T_active ≥ 73 d bracketed by the two NEOWISE visits (MJD 58786 and 58860; Table 1). Equation (13) therefore misses a factor T_active/τ ≈ 15-25. Applying this factor to the paper's own γ = 3.3 case raises M from 1.6×10^8 kg to roughly 3-4×10^9 kg, which reaches the lower edge of the adopted stream-mass range (4×10^9-10^11 kg). The statement in the abstract and Section 5.1.1 that steady mass loss is 'an order of magnitude too small regardless of plausible assumptions' is not supported by the paper's equations and must be revisited after correcting the time integration.
  2. [§4.1, Eqs. (11)-(12)] The reported fractional active area is not independently measured by the NEOWISE data. Substituting Eq. (11) into Eq. (12) gives fA = rs^2/(4 rn^2), so the measured Qdust cancels algebraically. With the adopted rs ≈ 2 m and rn = 160 m, fA = 3.9×10^-5, which reproduces the reported mean value. The abstract's 'smallest fractional active area' claim is therefore inherited from the 1956 Phoenicid dust-size and ejection-velocity assumptions (Watanabe et al. 2005), not from the new photometry. The paper should state this cancellation explicitly and reframe the fA result as a consistency check of the SSA model rather than a new measurement.
  3. [§4.1, Table 5 and §3.2] The uncertainties quoted for Md, Qdust and fA are statistical only and omit systematics in rn (160 ± 40 m), ρd = 1000 kg m^-3, ad = 2.0 µm, pv = 0.04, vd, and rs. The dust production rates are particularly sensitive to the SSA velocity model, which ties vd to rs; thus the derived rates already embed the Phoenicid stream parameter choices. A systematic error budget or a sensitivity table over these parameters is needed before the order-of-magnitude stream-mass comparison can be judged robust.
minor comments (3)
  1. [§3.3 and §6] The rotation period Prot = 8.8536 ± 0.3860 hr is presented in the summary as a finding, despite the low significance level of 30.5% and the authors' own caution that the light curves may not be reliable. The abstract and summary should carry the same caveat as the text.
  2. [§5.1.1] The size distribution integral in Eq. (14) should be stated more carefully: the normalization of n(a) is not defined, and the text should specify that \(\bar{a}\) is computed over the same a1-a2 interval in both the numerator and denominator.
  3. [Throughout] The manuscript contains several typographical and OCR artifacts (e.g., 'Pho enicids' in the running title, 'mc' in §2.2, 'our finings' in §5.1.2). A careful proofread is needed.

Circularity Check

1 steps flagged · score 6.0 of 10

The 'smallest fractional active area' fA is not measured by NEOWISE: combining the paper's Eqs. (11) and (12) gives fA = rs^2/(4 rn^2), so the headline value is a rescaling of the adopted SSA ice-patch radius inherited from Watanabe et al. (2005), not a new measurement.

  1. self definitional [Section 4.1, Equations (11) and (12) and following text]
    "fdg = Qdust / (π r^2_s Fs), (11) ... The fraction of active area (ice patch) on the nucleus surface, fA, is derived using Luu & Jewitt (1992), fA = Qdust / (4π r^2_n fdg Fs). (12) Using the above parameters, we find fA ∼ 5.1×10−5 in Visit A and fA ∼ 2.4×10−5 in Visit B, respectively."

    Substituting Eq. (11) into Eq. (12) gives fA = r_s^2/(4 r_n^2). Both Qdust and Fs cancel, so the NEOWISE-derived dust production rate does not enter the result. The quoted fA values are therefore the square of the adopted SSA ice-patch radius r_s ≈ 1.6–2.3 m (derived from 1956 Phoenicid meteoroid sizes and vd ≈ 0.5 m/s, Watanabe et al. 2005, with the present author as coauthor) divided by 4 r_n^2 with r_n = 160 ± 40 m (Jewitt 2006). The abstract's headline claim that fA = 3.8 ± 1.9 × 10−5 is 'the smallest yet reported' is thus an identity applied to pre-selected inputs, not a measurement from the new W1/W2 photometry.

full rationale

The one clear circular step is the fractional active area. The paper presents fA as a derived result of the NEOWISE observations, but algebraically fA ≡ r_s^2/(4 r_n^2). Since r_s is set by the SSA model using meteoroid sizes and ejection velocities from Watanabe et al. (2005) — a paper coauthored by the present author — and r_n is taken from Jewitt (2006), the 'smallest active fraction' claim is inherited from those inputs by construction. This is a self-definitional reduction of a headline numerical result. The rest of the paper is not circular in the same sense: Qdust and fdg are computed from the measured NEOWISE Cd and the SSA velocity model, and the stream-mass discussion in Section 5.1.1 uses Equation (13) with observed Cd and assumed particle power laws, so it does not reduce to its inputs by definition. A separate, non-circular concern is that Equation (13) multiplies an instantaneous aperture dust mass by Norb, implicitly restricting activity to the few-day aperture residence time rather than the ≥73-day observed active arc; if that factor is corrected, the steady-loss estimate rises by roughly an order of magnitude, weakening the paper's 'another mass supply is required' conclusion. That is a correctness or modeling issue, not a circularity, so it is not scored here. The total circularity score reflects that one central claimed result, featured in both the abstract and summary, is forced by the adopted parameters through Equation (12) rather than by the new NEOWISE data.

Assumptions & free parameters 8 free parameters · 6 assumptions · 1 invented entities

The central results rest on a chain of assumed physical parameters. The most consequential is rs ~ 2 m, which cancels out of fA via Equation (12) and sets vd in the dust production rate. The precursor breakup scenario also depends on the assumed stream mass range and the adopted rotation period.

free parameters (8)
  • De (effective diameter) = 1.43 +/- 0.04 km (Visit A), 0.96 +/- 0.01 km (Visit B)
    Single free parameter fitted to the two measured W1 and W2 flux densities in the reflected sunlight plus thermal emission model, Section 3.4.
  • rs (ice patch radius) = 1.6 to 2.3 m (adopted ~2 m), with an upper limit ~31 m
    Derived from the SSA model using 1956 Phoenicid meteoroid radius and velocity constraints; not measured by NEOWISE. Drives fA and vd.
  • rn (nucleus radius) = 160 +/- 40 m
    Assumed from Jewitt (2006); used in fA, Qdust and destruction timescale calculations.
  • ad (dust particle radius) = 2.0 micrometers
    Assumed mean dust radius for W1 and W2 coma brightness, adjusted from Bauer et al. 2011.
  • rho_d = rho_n (bulk density) = 1000 kg m^-3
    Assumed equal bulk density for dust and nucleus, following Jewitt (2006).
  • pv (geometric albedo) = 0.04
    Assumed geometric albedo typical of low-Tisserand Jupiter-family comet nuclei.
  • vd (dust ejection velocity) = 11.5 m/s for 2.0 micrometer dust
    Computed from the SSA model via Equation (2), not directly measured; NEOWISE FWHM gives only an upper limit of 48 m/s for 2.3 micrometer dust.
  • Prot (rotation period) = 8.8536 +/- 0.3860 hr
    Selected from a low-significance (30.5%) DFT fit to the weighted mean light curve and later used as an input to the destruction timescale calculation.
assumptions (6)
  • domain assumption The small-source approximation (SSA) model of Jewitt et al. (2014) correctly relates dust ejection velocity, particle size, ice patch radius, and nucleus gravity.
    Used in Section 3.2 to derive rs, vd, and the dust production rates; the model is taken from prior literature, not validated for 289P in this paper.
  • domain assumption The 1956 Phoenicid meteoroid constraints, ad >= 1 mm and vd ~ 0.5 m/s, are representative of dust ejected from 289P's current ice patch.
    These values from Watanabe et al. (2005) set rs ~ 2 m via Equation (2); if they do not apply to current activity, fA and Qdust change substantially.
  • domain assumption The Halley-Marcus composite phase function remains valid at phase angles near 70 degrees.
    Used in the Af-rho method, Equations (9) and (10); the author notes a critical point at 55 degrees and uses the Marcus branch for Visit B.
  • domain assumption Cometary dust radiates as a blackbody at Td = 1.03 Tbb with emissivity 0.9.
    Used in the thermal emission model, Equation (6), to separate reflected and thermal flux; the temperature offset is empirical from Stevenson et al. (2015).
  • domain assumption The Phoenicid stream mass is of order the parent body mass, and the 1956 stream mass estimate of about 1e11 kg bounds the possible range from about 4e9 to 1e11 kg.
    Central to the mass budget argument in Section 5.1.1; based on an order-unity analogy with other meteoroid streams, not measured directly.
  • ad hoc to paper The precursor body had a radius of roughly 170 m and underwent rotational destruction between 1743 and 1819.
    Postulated in Section 5.1.2 to supply the missing Phoenicid mass; there is no direct observational evidence for the precursor body itself.
invented entities (1)
  • Sub-km precursor body with radius ~170 m
    purpose: Supplies the missing Phoenicid stream mass via rotational disruption in 1743 to 1819, with 289P as the surviving remnant.
    Inferred entirely from the mass budget and the current low activity of 289P; no direct detection or independent dynamical fingerprint is presented.

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Cite this review

Pith. "Pith review of Comet 289P/Blanpain: Near-Perihelion Activity and the Phoenicids." pith.science (2026). https://pith.science/paper/GEGDUGX4

@misc{pith2026241113501,
  author       = {Pith},
  title        = {Pith review of: Comet 289P/Blanpain: Near-Perihelion Activity and the Phoenicids},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/GEGDUGX4}},
  note         = {Machine review of arXiv:2411.13501}
}
abstract

We present NEOWISE observations of Jupiter family comet 289P/Blanpain, the parent body of the Phoenicid meteoroid stream. Near-infrared images at 3.4$\mu$m ($W1$) and 4.6$\mu$m ($W2$) were obtained near perihelion on two occasions: UT 2019-10-30 (inbound, heliocentric distance $R_{\rm h}$ = 1.20 au) and UT 2020-01-11/12 (outbound, $R_{\rm h}$ = 1.01 au). To assess faint activity, we establish constraints on dust production driven by the limited sublimating area of water ice, based on studies of the 1956 Phoenicids. The ejected dust mass is $M_{\rm d}$ = 4100 $\pm$ 200 kg (inbound) and 1700 $\pm$ 200 kg (outbound), respectively. The dust production rates are $Q_{\rm dust}$ = 0.01$-$0.02 kg s$^{-1}$, corresponding to dust-to-gas production ratio 2 $\leqslant\,f_{\rm dg}\,\leqslant$ 6. The resulting fractional active area, $f_{\rm A}$ = 3.8 $\pm$ 1.9 $\times 10^{-5}$, is the smallest yet reported. The absence of 4.6$\mu$m ($W2$) excess suggests that 289P contains negligible amounts of CO$_2$ and CO. Time-resolved analysis of weighted mean of $W1$ and $W2$ magnitudes finds a distinctive peak amplitude in the light curve having a rotational period $P_{\rm rot}$ = 8.8536 $\pm$ 0.3860 hr, however, further verification is needed. The perihelion-normalized nongravitational acceleration, $\alpha_{\rm NG}^\prime$ = 3.1 $\times$ 10$^{-6}$, is approximately an order of magnitude smaller than the trend observed for well-studied comets, consistent with weak outgassing. Current dust production from 289P, regardless of plausible assumptions for particle size and distribution, is an order of magnitude too small to produce the Phoenicid stream within its $\sim$300 yr dynamical lifetime. This suggests another mass supply, probably in 1743$-$1819, rapid rotational destruction of a sub-km precursor body, resulting in fragments equaling the mass of an object with radius $\sim$ 100 m.

Figures

Figures reproduced from arXiv: 2411.13501 by the authors.

Figure 1
Figure 1. The ICORE coadded images of 289P (center) in Visit A (MJD 58786: UT 2019-10-30, inbound). Both frames have a size of 277′′ × 277′′. The left panel shows the W1-band image (38.5 seconds integra￾tion) with the FWHM θF = 7′′ .2, while the right panel shows the W2-band image (46.2 seconds integration) with θF = 7′′ .7. Heliocentric, WISE-centric distances and phase angle were Rh = 1.20 au, ∆ = 0.40 au and α = 49.8◦ , re… view at source ↗
Figure 2
Figure 2. The median-combined images of 289P (center) in Visit B (MJD 58860: UT 2020-01-11/12, outbound). Both frames have a size of 200′′ × 200′′ with an integration time of 15.4 seconds. The left panel shows the W1-band image with the FWHM θF = 6′′ .6, while the right panel shows the W2-band image with θF = 6′′ .9. A 40′′ scale bar is included. Rh = 1.01 au, ∆ = 0.09 au and α = 70.2◦ . N and E exhibit the cardinal direction… view at source ↗
Figure 3
Figure 3. Normalized surface brightness profiles of 289P (blue circles) and a field star (black circles), from median-combined W1 image in Visit B (MJD 58860: UT 2020-01-11/12, outbound) ( [PITH_FULL_IMAGE:figures/full_fig_p031_3.png] view at source ↗
Figures from the paper (11 more)
Figure 4
Figure 4. Figure 4: Same as [PITH_FULL_IMAGE:figures/full_fig_p032_4.png]
Figure 5
Figure 5. Figure 5: Models of the ejection velocity of dust from 289P as a function of particle radius. The SSA model (blue curve) and the Whipple model (red curve) are compared. The blue circle marks the particle radius ad = 1 mm and the velocity vd = 0.5 m s−1 determined by the 1956 Pho…
Figure 6
Figure 6. Figure 6: The left panel shows W1-band photometry of 289P in Visit A (MJD 58786: UT 2019-10-30, inbound), phased to the two-peaked period Prot = 14.8224 ± 2.9899 hr ≈ 15 ± 3 hr. The blue curve displays fitting result having amplitude ∼ 1.3 mag. The right panel shows spectral ana…
Figure 7
Figure 7. Figure 7: Same as [PITH_FULL_IMAGE:figures/full_fig_p035_7.png]
Figure 8
Figure 8. Figure 8: Same as [PITH_FULL_IMAGE:figures/full_fig_p036_8.png]
Figure 9
Figure 9. Figure 9: Calculated spectral energy distribution and measured flux densities from the 289P composite image in Visit A (MJD 58786: UT 2019-10-30, inbound). The flux densities at W1 (3.4µm) and W2 (4.6µm) are shown as points. The uncertainties are within the point size. The refle…
Figure 10
Figure 10. Figure 10: Same as [PITH_FULL_IMAGE:figures/full_fig_p038_10.png]
Figure 11
Figure 11. Figure 11: Relationship between JFC nuclei radius and fractional active area, fA. The fA of 289P is estimated near its perihelion, despite being among the lowest in JFCs, comparable to the inactive state of 169P [PITH_FULL_IMAGE:figures/full_fig_p039_11.png]
Figure 12
Figure 12. Figure 12: Phoenicid stream mass is plotted as a function of the differential power-law index, γ, as a blue solid line (γ 6= 3.0, 4.0 in Equation (13)). The possible stream mass range (Ms), based on the nucleus mass (Mn, Jewitt 2006) and the estimated stream mass (∼ 1011 kg, Jen…
Figure 13
Figure 13. Figure 13: Precursor spin-up timescale is plotted as a function of radius of ice sublimating area (patch), rps, from Equation (15). Solid and dashed curves (black) show kT = 0.05 and 0.007 (Jewitt 1997, 2021), respectively. A horizontal band (yellow) indicates the range of spin-…
Figure 14
Figure 14. Figure 14: Nucleus radius versus perihelion-normalized nongravitational acceleration of 289P (blue symbol) and comparison with those of well-studied short period comets (yellow symbols). The dashed red line indicates the trend found by fitting from the latter data, which is Hall…

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Reference graph

Works this paper leans on

22 extracted references · 21 canonical work pages

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    a Modified Julian Date of the mid-point of the observation

    Weighted Mean of W 1 and W 2 Magnitudes Visit MJD a W 1b W 2c Wwmd (mag) (mag) (mag) A 58786.0688 15.181 ±0.563e 11.662h 12.056±0.188 58786.1997 15.491 f 12.577h 13.474±0.166 58786.2650 15.645 f 13.033±0.151g 13.561±0.135 58786.3304 15.800 ±0.392e 13.490±0.198g 13.960±0.177 58786.3959 15.037 ±0.367e 12.860h 13.358±0.176 58786.4613 14.916 ±0.307e 12.231±0....

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    08 for asteroids, if a < a J = 5.2 au ( Jewitt et al. 2015 ). For reference, we list other comet-asteroid thresholds of TJ = 3 . 05 (Tancredi 2014 ) and TJ = 3 . 10 ( Hsieh & Haghighipour 2016 ) (see a re- view, Jewitt & Hsieh 2022 ). 26 Kasuga (2024) T able

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    Magnitude and Flux Density Visit W 1a W 2b W 1c W 2d (mag) (mag) (Jy) (Jy) Ae 15.903±0.133 13.035 ±0.066 1.35 ±0.17×10−4 1.05±0.06×10−3 Bf 12.525±0.046 9.714 ±0.039 3.02 ±0.13×10−3 2.24±0.08×10−2 Note—Magnitudes are measured from the composite images and conv erted to flux densities for each band ( W right et al. 2010 ). a Measured magnitude at W 1 from th...

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    Rh=1.20 au, ∆=0.40 au, and α =49.8◦

    e MJD 58786: UT 2019-10-30, inbound. Rh=1.20 au, ∆=0.40 au, and α =49.8◦. f MJD 58860: UT 2020-01-11/12, outbound. Rh=1.01 au, ∆=0.09 au, and α =70.2◦. AASTEX Comet 289P/Blanpain and the Phoenicids 27 T able

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    28 Kasuga (2024) T able

    Assumed uncertainty is 0.2 mag. 28 Kasuga (2024) T able

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    b Cross-section of all the dust particles

    (kg) (kg s −1) (kg s −1) Af 1.43±0.04 1.53 ±0.09 4100 ±200 1.0 ±0.1×10−2 1.0±0.2×10−2h Bg 0.96±0.01 0.64 ±0.08 1700 ±200 2.0 ±0.3×10−2 4.0±0.2×10−2i Note— a Effective diameter of a circle having the same area as the sum o f all the dust particles and nucleus. b Cross-section of all the dust particles. c Dust mass from Equation ( 7). d Dust production rate ...

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    Both frames have a size of 277 ′′ × 277′′

    The ICORE coadded images of 289P (center) in Visit A (MJD 58786: UT 2019-10-30, inbound). Both frames have a size of 277 ′′ × 277′′. The left panel shows the W 1-band image (38.5 seconds integra- tion) with the FWHM θF = 7′′. 2, while the right panel shows the W 2-band image (...

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    The cardinal directions ( N and E), the direction of the negative heliocentric velocity vector ( −V ), and the anti-solar direction ( −⊙) are marked

    Heliocentric, WISE -centric distances and phase angle were Rh = 1.20 au, ∆ = 0.40 au and α = 49.8◦, respectively. The cardinal directions ( N and E), the direction of the negative heliocentric velocity vector ( −V ), and the anti-solar direction ( −⊙) are marked. A 40 ′′ scale...

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  3. [13]

    Both frames have a size of 200 ′′ × 200′′ with an integration time of 15.4 seconds

    The median-combined images of 289P (center) in Visit B (MJD 58860: UT 2020-01-11/12, outbound). Both frames have a size of 200 ′′ × 200′′ with an integration time of 15.4 seconds. The left panel shows the W 1-band image with the FWHM θF = 6′′. 6, while the right panel shows th...

    2020

  4. [14]

    The FWHM of 289P is θF = 6′′

    Normalized surface brightness profiles of 289P (blue circle s) and a field star (black circles), from median-combined W 1 image in Visit B (MJD 58860: UT 2020-01-11/12, outbound) (Figure 2, left panel). The FWHM of 289P is θF = 6′′

    2020

  5. [15]

    32 Kasuga (2024) 0.10 1.00 1 10 100 Star 289P Normalized Surface Brightness Linear Distance [arcsec] Figure

    The linear distance > 40′′ is precluded (vertical dashed line) due to the nonuniform background, preventing further profile analysi s. 32 Kasuga (2024) 0.10 1.00 1 10 100 Star 289P Normalized Surface Brightness Linear Distance [arcsec] Figure

    2024

  6. [16]

    The SSA model (blue curve) and the Whipple model (red curve) are comp ared

    Models of the ejection velocity of dust from 289P as a functio n of particle radius. The SSA model (blue curve) and the Whipple model (red curve) are comp ared. The blue circle marks the particle radius ad = 1 mm and the velocity vd = 0.5 m s−1 determined by the 1956 Phoenicid...

    2024

  7. [17]

    The blue curve displays fitting result having amplitude ∼ 1.3 mag

    The left panel shows W 1-band photometry of 289P in Visit A (MJD 58786: UT 2019-10-30, inbound), phased to the two-peaked period Prot = 14.8224 ± 2.9899 hr ≈ 15 ± 3 hr. The blue curve displays fitting result having amplitude ∼ 1.3 mag. The right panel shows spectral analysis cu...

    2019

  8. [18]

    The significance level is ∼45%

    Same as Figure 6 but from the W 2-band, presenting the Prot =13.2168±2.3551 hr ≈ 13 ± 2 hr with an amplitude ∼2.0 mag in the left panel and the maxima Prot = 0.5507 day (= 13.2168 hr) in the right panel. The significance level is ∼45%. 36 Kasuga (2024) 11.5 12.0 12.5 13.0 13.5 ...

    2024

  9. [19]

    The flux densities at W 1 (3.4µ m) and W 2 (4.6µ m) are shown as points

    Calculated spectral energy distribution and measured flux d ensities from the 289P composite image in Visit A (MJD 58786: UT 2019-10-30, inbound). The flux densities at W 1 (3.4µ m) and W 2 (4.6µ m) are shown as points. The uncertainties are within the point s ize. The reflected ...

    2024

  10. [20]

    Rh=1.01 au, ∆=0.09 au, and α =70.2◦ are used for the models

    Same as Figure 9 but in Visit B (MJD 58860: UT 2020-01-11/12, outbound). Rh=1.01 au, ∆=0.09 au, and α =70.2◦ are used for the models. AASTEX Comet 289P/Blanpain and the Phoenicids 39 10-5 10-4 10-3 10-2 10-1 100 101 100 1000 10000 289P 169P JFCs Active Fraction, fA JFC Nuclei ...

    2020

  11. [21]

    The fA of 289P is estimated near its perihelion, despite being among the lowe st in JFCs, comparable to the inactive state of 169P

    Relationship between JFC nuclei radius and fractional acti ve area, fA. The fA of 289P is estimated near its perihelion, despite being among the lowe st in JFCs, comparable to the inactive state of 169P. 40 Kasuga (2024) Ms Mn γ−range of Comet−sourced Streams105 106 107 108 10...

    2024

  12. [22]

    Phoenicid stream mass is plotted as a function of the different ial power-law index, γ, as a blue solid line ( γ ⁄= 3.0, 4.0 in Equation ( 13)). The possible stream mass range ( Ms), based on the nucleus mass (Mn, Jewitt 2006 ) and the estimated stream mass ( ∼ 1011 kg, Jennisk...

    2006

  13. [23]

    Solid and dashed curves (black) show kT = 0.05 and 0.007 ( Jewitt 1997 , 2021), respectively

    Precursor spin-up timescale is plotted as a function of radi us of ice sublimating area (patch), rps, from Equation ( 15). Solid and dashed curves (black) show kT = 0.05 and 0.007 ( Jewitt 1997 , 2021), respectively. A horizontal band (yellow) indicates the ran ge of spin-up t...

    2024

  14. [25]

    b Eccentricity

    aa eb ic qd ω e Ω f Qg Porbh TJi (au) (deg) (au) (deg) (deg) (au) (yr) 3.045 0.685 5.897 0.959 9.849 68.924 5.132 5.315 2.817 Note— From NASA JPL Small-Body Database Lookup (2458746.5 (2019 - Sep-20.0): Solution Date 2024-Jul-26) a Semimajor axis. b Eccentricity. c Inclination...

    2019

Pith tools

Reviewed August 12, 2026 · model on record in the stance chip above.