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Asteroid–Meteoroid Complexes
Asteroid–Meteoroid Complexes (Review)
Kasuga & Jewitt (2019), Chapter 8 in the book "Meteoroids: Sources of Meteors on Earth and Beyond", Ryabova G. O., Asher D. J., and Campbell-Brown M. D. (eds.), Cambridge University Press, 2019, p.187-209 (pdf).
Figure 1. Objects are arranged as below.
Phaethon, 2005 UD
1999 YC
2003 EH1, 2P/Encke
2003 WY25, 169P/NEAT
# 2P, courtesy NASA/JPL-Caltech/M. Kelley (Univ. of Minnesota).
This chapter reviews recent research on the relationship between meteors and their parent bodies. While many meteor showers originate from cometary ejecta, the two most prolific annual showers, the Geminids and the Quadrantids, are linked to objects with apparently asteroidal properties. In recent decades, a number of Asteroid-Meteoroid Complexes have been confirmed through dynamic and observational studies, comprising meteoroid streams and macroscopic fragments. We examine the characteristics of these complexes, including some minor streams, and review how spectroscopy of meteor showers has been used to investigate perihelion-dependent thermal alteration in interplanetary space. The primary scientific goal is to trace the physical and dynamic properties of these complexes back to their evolutionary pathways, providing insight into the diverse processes of meteoroid stream formation. We also discuss key outstanding questions to be answered in the next decade.
Meteor showers and their (potentially) parent bodies reviewed.
Geminids –– Phaethon, 2005 UD and 1999 YC
Quadrantids –– 2003 EH1 and 96P/Machholz 1
Capricornids –– 169P/NEAT, P/2003 T12 and 2017 MB1
Taurids –– 2P/Encke
Taurids–Perseids –– 1566 Icarus and 2007 MK6
Phoenicids –– 2003 WY25 (= 289P/Blanpain)
Andromedids –– Comet 3D/Biela
Figure 2. Distribution of the parent bodies (black circles) in the semimajor axis vs. orbital eccentricity plane. The distributions of asteroids (brown dots) and comets (light-blue dots) are shown for reference. The lines for TJ = 3.08 with i = 0°(solid curve) and with i = 9◦(dotted curve) broadly separate asteroids and comets. Perihelion distances q = 0.25, 0.5 and 1 au are shown as red curves.
Comet 289P/Blanpain (= 2003 WY25)
Comet 289P/Blanpain: Near-perihelion Activity and the Phoenicids
Figure. The NEOWISE W2-band image of 289P (UT 2019-10-30, inbound). The frame size is 277′′ × 277′′ (46.2 seconds integration; 6 frames). Neither tail nor distinctive coma is found. Heliocentric, WISE-centric distances and phase angle were Rh = 1.20 au, ∆ = 0.40 au and α = 49.8◦, respectively.
Comet 289P/Blanpain was discovered in 1819 by J.-J. Blanpain (Kronk, 2003) and linked to the Phoenicid meteor shower based on their orbital similarities (Ridley, 1963). After initial observations, it remained lost for nearly two centuries. In 2003, the near-Earth asteroid 2003 WY25 was discovered (e.g. Larson et al. 2003; Ticha et al. 2003). Its orbit and Tisserand parameter suggest it is a Jupiter-family comet. Orbital similarities to 289P indicate they may be the same object (Foglia et al. 2005). This has been verified by the Phoenicid meteor shower. The Phoenicids storm was observed in 1956 (Huruhata & Nakamura 1957). Assuming 2003 WY25 = 289P, dust trail calculations prove that the 1760-1808 dust trails were responsible for the event (Watanabe et al. 2005; Jenniskens & Lyytinen 2005). In 2004, cometary activity in 289P was confirmed, with a small nucleus and low mass-loss rate of ~0.01 kg s−1 (Jewitt 2006). Subsequent observations in 2013 revealed an asymmetric coma and tail at far distant place from the Sun, Rh = 3.9 au (Williams et al. 2013). Given the short dynamical age of the Phoenicid stream (< 300 yrs), the limited mass-loss implies that the stream have formed impulsively, through the breakup of the precursor body (reviewed in Kasuga & Jewitt 2019).
NEOWISE observations of 289P's 2019–2020 perihelion return
The near-infrared images at 3.4μm (W1) and 4.6μm (W2) were obtained around perihelion on two occasions: UT 2019-10-30 (inbound, Rh = 1.20 au) and UT 2020-01-11/12 (outbound, Rh = 1.01 au) (Figure). The derived dust production rates are 0.01−0.02 kg s−1. We find too low dust production rates from both objects to form their streams, suggesting they should be, or used to be, ejecting mass other than activity driven by steady-state sublimation of ice. Despite considering reasonable particle sizes and distributions, its current dust production rate is too low to account for the Phoenicid stream within its 300-year dynamical lifetime. This suggests that a significant mass release event, probably due to the rapid rotational breakup of a precursor body between 1743 and 1819, produced fragments with a total mass equivalent to a 100-meter object. 289P is mostly likely a remnant of a sub-kilometer precursor comet that may have been a low-activity Jupiter-family comet.
Near-Earth Asteroid (3200) Phaethon
WISE/NEOWISE Multiepoch Imaging of the Potentially Geminid-related Asteroids:(3200) Phaethon, 2005 UD, and 1999 YC
Figure. The WISE W3-band image of Phaethon in 17.6s integration (2 × 8.8s) taken on UT 2010 January 7. The frame size is 200'' × 200''. The Phaethon-associated dust trail (Geminid stream) is not detected at Rh = 2.3 au, corresponding to an upper limit to the optical depth of τ < 7 × 10−9 .
References. [1] Whipple, F. L. (1983) IAU Circ. 3881, 1. [2] Blaauw, R.C. (2017) P&SS, 143, 83-88. [3] Yanagisawa et al. (2021) P&SS, 195, id.105131. [4] Jewitt & Hsieh (2024), Chapter in Comets III (Univ. of Arizona Press) [5] Kasuga & Jewitt (2019), Chapter 8 in Meteoroids: Sources of Meteors on Earth and Beyond (Cambridge Univ. Press) [6] Masiero et al. (2021), PSJ, 2, id.165. [7] Hui (2023), AJ, 165, id.94. [8] Zhang et al. (2023), PSJ, 4, 70 [9] Ozaki et al. (2022), AcAau, 196, 42–56. [10] Wright et al. (2010), AJ, 140, 1868–1881. [11] Mainzer et al. (2011), ApJ, 736, id. 100. [12] Masiero et al. (2019), AJ, 158, id. 97. [13] Bauer et al. (2008), PASP, 120, 393. [14] Ryabova (2018), MNRAS, 479, 1017–1020.
The near-Earth asteroid (3200) Phaethon seems to be dynamically associated with the Geminid meteoroid stream [1]. The Geminid meteoroid stream consists of near millimeter-scale or larger solid particles, up to tens of centimeters, as measured by radar [2] and lunar impact flushes [3]. The notable orbital feature of both is the small perihelion distance, q=0.14au, where repeatedly exposed to intense thermal process which possibly causes the Phaethon’s recurrent activity [4]. Spectroscopic measurements of sodium (Na) content of the Geminid meteors have been utilized for studying the thermal processes on Phaethon. The Geminids exhibit the extreme variety in their Na content, from depletion (free) of the Na abundance to near solar-like values. The thermal desorption of Na is unlikely to occur for the Geminid stream phase even at q=0.14au. It takes too long timescale to sublimate Na compared to the stream age. Therefore the Na-loss observed in the Geminids must have originated from the thermal process of the parent, Phaethon [5]. The Na-driven perihelion activity is proposed both by simulation/experiment [6] and by observations [7, 8].
We study the space-based thermal infrared data of Phaethon. The WISE/NEOWISE decadal observing epochs of the infrared data provide with information about where in the orbit the object is along with the limits, as we might expect a strong variation in production at different points in the orbit. Another motivation is to find an activity mechanism far from perihelion, which is different from thermal-driven. This study provides a groundwork for JAXA DESTINY+, which is planning to flyby at a distance of 500km from Phaethon in 2030 (extended from 2028) [9]. The data are taken by the NASA Wide-field Infrared Survey Explorer [WISE; 10] and the Near-Earth Object WISE [NEOWISE; 11, 12]. WISE, the full sky survey simultaneously obtained the infrared data at the four infrared wavelength bands 3.4μm(W1), 4.6μm(W2), 12μm(W3), and 22μm(W4) in 2010. The NEOWISE survey started in December 2013 and is ongoing project taking the shorter two-bands at W1 [13] and W2. The multiple observing epochs contain the four-bands data (W1–W4), giving the best opportunities to constrain the dust environments around Phaethon over the last decade (2010 ~ 2017).
We find no strong variation in the production rate at different epochs, and find no dependency on the location of the object in the orbit at the time of observation. No evidence of lasting mass loss found in the W1 image. The maximum dust production rate is 2 kg s−1, suggesting no strong dependency on heliocentric distance at 1.0–2.3 au. We find neither dust trail (Geminid stream) from Phaethon nor co-moving objects in the W3 and W4 images at the heliocentric distance of 2.3au. The upper limit to the optical depth along the trail direction is 7×10−9 (Figure). Correspondingly, during the DESTINY+ flyby phase (at 500km distance), a few 500μm-sized particles are to be encountered by the dust analyzer. Those relatively large particles are highly likely to be the Geminids. On the other hand, when DESTINY+ passes at 50,000km distance from Phaethon, several 10μm-sized particles are to be captured by the instrument. We also find the implications for the (Na) sodium-driven perihelion activity of Phaethon in relation to the consistently formed structure of the Geminid stream [14]. The ejected dust size, velocity and stream mass are comparatively matched with the Geminid study.
Planetary Defense
A Fireball and Potentially Hazardous Binary Near-Earth Asteroid (164121) 2003 YT1
Meteor Science applied for identifying Killer Asteroids
A bright fireball was detected in the sky over Kyoto, Japan at 15h58m19s UT 2017 April 28 by the SonotaCo Network (SonotaCo, 2009) (Figure). The network consists of dozens of cameras across Japan, monitoring sky to find sporadic fireballs and hazardous meteoroids. This fireball was simultaneously detected at 11 sites with 12 cameras. The trajectory is compatible with those of asteroid 2003 YT1 (e.g. Nolan et al. 2004). Orbital similarity between the detected fireball and the potential parent: 2003 YT1 is confirmed by D(sh)-criterion ≤ 0.0079 (The threshold ≤ 0.15 is given by Southworth & Hawkins (1963)). The absolute visual magnitude of the fireball is Mv= −4.10±0.42mag. The light curves give the meteoroid mass of m = 29 ± 1g, which corresponds to the size as = 2.7 ± 0.1cm with the density of 2700 kg m−3.
As for the binary system of 2003 YT1, the asynchronous state indicates the age of <104 yr, near or shorter than the upper limit to meteoroid stream lifetime. We examine potential dust production mechanisms for the asteroid, including rotational instability, resurfacing, impact, photoionization, radiation pressure sweeping, thermal fracture, and sublimation of ice. We find some of them capable of producing the meteoroid-scale particles. The YORP spin-up timescale is τY ∼ 2 Myr, which shortly induces rotational instability. The resulting end-state is a breakup/fission if it is the rubble-piled body held by a weak cohesive strength of Sc ∼ 240 N m−2. Rotational instability is presumed to cause mass shedding, in consideration of the recent precedents (e.g. (6478) Gault), possibly releasing millimeter–centimeter scale dust particles. Impacts by micrometeorites (size ≃1 mm) could be a trigger for ejecting the centimeter-sized particles. Radiation pressure may sweep out the millimeter-sized particles from 2003 YT1, which could be the source of faint meteors with an apparent magnitude of about +5 mag, but the centimeter-sized particles are too large to be removed. The other mechanisms are unprovable or unidentified (e.g. resurfacing, photoionization, thermal fracture and sublimation of ice).
Figure. Images capturing the 2017 fireball from different angles and a map showing where the cameras were located. The projection of fireball atmospheric trajectory (red arrow) including eleven observation sites (ID) and the lines of sight (thin-line) are depicted.
NAOJ Press Release 2020 (Japanese) (English)
NAOJ Highlights 2020 (Japanese)
AstroArts January, 2020 (Japanese)
ISAS/JAXA Planetary Defense Symposium 2023, Talk Summary (English)
Asteroid Family
Asteroid Family Physical Properties (Review)
Masiero, J. R., DeMeo, F., Kasuga, T. and Parker, A. H. (2015), Chapter in the Space Science Series Book "ASTEROIDS IV". Univ. of Arizona Press. pp 323-340.
AKARI/AcuA Physical Studies of Cybele Asteroid Family
AKARI/AcuA Physical Studies of Cybele Asteroid Family
Formation and Physical Characterization of Asteroid Families (Masiero et al. 2015)
The prevailing paradigm for asteroid family formation posits that a catastrophic collision disrupts a larger parent body. Consequently, members within a family are expected to exhibit physical properties that closely mirror the parent's composition and mineralogical history. Recent years have witnessed the release of extensive new datasets probing the physical properties of a vast number of asteroids, including many belonging to established families. This review delves into these datasets and the composite properties of asteroid families revealed by this wealth of new information. We further explore the limitations inherent in the current data and identify key areas demanding further investigation within this field.
Masiero et al. (2015) reviews the datasets: optical colors from SDSS, visible and IR spectroscopic surveys, infrared space surveys, asteroid light curves and phase curves, and polarimetric surveys of families. We determine the average characteristic properties for families: color, spectra, albedo, and size distributions of families. The homogeneity of families and use of physical properties to distinguish outliers, combined properties of individual families, and relationship between albedo and color are summarized. We discuss correlation of observed properties with the primordial composition of the main belt, properties of observed families contrasted with the background population, families as feeders for the NEO population, and families beyond the main belt. Open problems and future prospects are noted.
Figure. Average solar-corrected SDSS colors (points) and sample optical/NIR spectra (from SMASS) for all asteroid families listed in Table 1 in the review with sufficient data. Plots are scaled such that the interpolated reflectance at 0.55 μm equals the average visible geometric albedo (pV ) for the family from all infrared surveys. The “N” in the bottom right of each plot indicates the number of SDSS observations used, and taxonomic class is given when available. Note the reflectance scale in each plot is different.
The Sylvia Asteroids: Unveiling the History of the Cybele Region (Kasuga et al. 2012)
The Sylvia family (PDS ID 603), residing in the Cybele region beyond the 2:1 Jupiter mean motion resonance (3.27 < a ≤ 3.70 AU; Zellner et al., 1985), occupies the outer fringe of the Main Asteroid Belt. These asteroids, along with Hildas and Jupiter Trojans, likely experienced minimal contamination from inner solar system materials, offering an unadulterated perspective on the composition present near Jupiter following planetary migration. The Nice model posits their origin as trans-Neptunian objects (TNOs) scattered inwards during a period of dynamical chaos in the early solar system (Levison et al., 2009). However, spectral discrepancies between Cybele asteroids and Hildas/Trojans suggest they might represent material native to this specific region.
Kasuga et al. (2012) investigated the size and albedo distributions within the Sylvia family to elucidate their history. Their findings indicate that the largest Cybele asteroids (D > 80 km) are predominantly C- or P-type, and the optimal power-law fit for the size distribution aligns with a catastrophic collision event. However, the calculated mass and size of the parent body, assuming an equilibrium collisional cascade, yield collisional timescales exceeding the solar system's age. These timescales are comparable to those of the Hildas, while the Trojan population appears consistent with a collisional origin. Numerical simulations encompassing both the collisional formation and dynamical evolution of the Cybele asteroids are warranted for a more comprehensive understanding of their history.
Figures. (Left) Cumulative size distribution of 107 Sylvia (Cybele) asteroids. The derived power-law indexes are b = 0.17 (10 km <D < 20 km), 0.86 ± 0.03 (20 km <D < 80 km), and 2.39 ± 0.18 (D > 80 km). (Center) Histograms of diameters for 80 Sylvias in the different taxonomic types (22 C-types, 27 D-types, 29 P-types, and two S-types). The C- and P-type Sylvias are dominant at larger sizes (D > 80 km). The taxonomic diversity of the smaller Sylvias is confirmed. (Right) Same as Figure 7(center), but for geometric albedos. The C-, D-, and P-type Sylvias present low values of pv ⩽ 0.11.
High-albedo Primitive Asteroids
High-albedo C-complex Asteroids in the Outer Main Belt: The Near-infrared Spectra
Kasuga et al. (2013), AJ, 146, id.1
Near-Infrared Spectra of High-albedo Outer Main-Belt Asteroids
Near-Infrared Spectra of High-albedo Outer Main-Belt Asteroids
Kasuga et al. (2013, 2015) comprise the topic: origin and composition of high-albedo primitive asteroids in the outer main-asteroid belt. Here, those of two publications are summarized.
Orbital dynamics studies suggest that the parent body of asteroid Phaeton lies within the Pallas family, a population predominantly located in the outer-asteroid belt (de Leon et al., 2010). These objects, typically classified as C-, B-, or D-type asteroids, generally exhibit low albedos (reflectivity) due to their primordial and carbonaceous surface compositions. However, recent infrared all-sky surveys have revealed a significant presence of high-albedo primitive asteroids within this region (Rivkin & Emery, 2010). Water ice (potentially accompanied by organic material) has been proposed as a primary contributor to their high albedo, and detections of such ice have been reported (Rivkin & Emery, 2010).
To investigate the composition of high-albedo primitive asteroids, we conducted a near-infrared spectroscopic survey by Subaru. Our results unveil an excess of magnesium relative to iron, as inferred from the abundance ratios of these elements. Additionally, we find the possible presence of thermally evolved differentiated material (crystalline pyroxene) (Figure). These findings align with observations and exploration results of comets, meteor spectra, and the material science characteristics associated with the formation of extrasolar planetary systems.
The inclusion of crystalline pyroxene in the modeled spectrum improves the fit to the observational data, indicating the potential presence of this high-temperature alteration product on the surface of asteroid (1576) Fabiola. This finding suggests that the asteroid has undergone thermal processing, likely due to past impact events or other heating mechanisms, resulting in the formation of crystalline pyroxene. The possible presence of crystalline pyroxene on the asteroid provides insights into the asteroid's thermal history and the processes that have shaped its surface composition. This discovery contributes to our understanding of asteroid evolution and the diverse materials found within the asteroid population.
Figure. Observed Reflective Spectrum and Model of Asteroid (1576) Fabiola. (a) Modeled spectrum using amorphous silicates, as in general. (b) Modeled spectrum incorporating crystalline pyroxene, a high-temperature alteration product, to achieve a better fit to the observational data.
Meteor Spectroscopy
Is a 2004 Leonid meteor spectrum captured in a 182 cm telescope?
Kasuga, T., Iijima, T., and Watanabe, J. (2007), A&A, 474, 639 - 645. (–pdf–)
A meteor spectrum was serendipitously captured in the visual-near IR wavelength region using the 182 cm telescope at the Mount Ekar Station of the Astronomical Observatory of Padova, Italy on 2004 Nov. 18 at 02:15:24.3 UT. During a 3600s slit spectroscopic exposure, a meteor passed through the slit. Given the observing date and sky location, the detected meteor is likely to be a Leonid.
Figure. A serendipitously captured meteor spectrum. Calibrated flux density is in units of 10−14 erg s−1 cm−2 Å−1 . The red curve shows the observed spectrum, while the blue curve is the best-fit model using atomic catalog lines and first positive band of N2. Residuals to the fit are shown with black fine dots below the spectrum. The green curve represents the model of the first positive band of N2 with a derived excitation temperature of N2 = 8010 ± 260 K. Excitation temperature of O I, N I, Hα I, Si II, and Na I are set as 10,000 K and 5500 K, respectively.
Previous understanding of fast meteor spectra as having only two excitation temperature components (5000 K and ~10,000 K) often inadequately explains observations due to a lack of physical correlation among spectral line parameters. This study aimed to address this limitation by investigating the relationships between excitation temperatures, observed fluxes, upper energy levels, and Einstein A coefficients in the visual to near-infrared region.
By focusing on the upper energy levels and Einstein A coefficients, and employing a model fitting nitrogen(N2)’s first positive band and total Si II under quasi-neutral conditions, we identified two new excitation temperature regimes: a mid component at ~8000 K for N2 emissions and a much hotter component (jet) above 10,000 K.
The inclusion of these additional components enabled a more accurate reproduction of observed high-speed meteor spectra. This suggests that the thermal structure of high-speed meteor plasmas is more complex than the traditional two-component model. Our findings indicate that high-speed meteor spectra likely comprise at least four distinct excitation temperature regimes: the main, mid, hot, and jet (hotter) components. The updated understanding offers a more comprehensive framework for interpreting the physical conditions within meteor plasmas.
Future. For its validity, we will consider a pressure balance and an equivalence of metal abundances among four types of continuous components. The former is considered in this study, but the latter in each component is not estimated. It might be good to apply to the Saha function to metal elements, under the old and new components conditions. To derive them, we use high-resolution meteor spectra from the near UV to near IR wavelength region, which includes neutral and ionized atomic emission lines and the nitrogen band for each component.
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