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Orbital Characterization of Superbolides Observed from Space: Dynamical Association with Near-Earth Objects, Meteoroid Streams, and Identification of Hyperbolic Meteoroids
There is an unceasing incoming flux of extraterrestrial materials reaching the Earth atmosphere. Some of these objects produce luminous columns when they ablate during the hypersonic encounter with air molecules. A few fireballs occur each year bright enough to be detected from space. The source of these events is still a matter of debate, but it is generally accepted that they are of sporadic origin. We studied the NASA-JPL Center for NEOs Studies (CNEOS) fireball database to infer the dynamic origin of large bolides produced by meter-sized projectiles that impacted our planet. These likely meteorite-dropping events were recorded by the US Government satellite sensors. We estimated the false-positive rate and analyzed the time evolution of multiple orbit dissimilarity criteria concerning potential associations with near-Earth objects and meteoroid streams. We found that at least 16% of the large bolides could be associated with meteoroid streams, about 4% are likely associated with near-Earth asteroids, and 4% may be linked to near-Earth comets. This implies that a significant fraction of meter-sized impactors producing large bolides may have an asteroidal or cometary origin. In addition, we found at least three bolides having hyperbolic orbits with high tensile strength values. Meter-sized meteoroids of interstellar origin could be more common than previously thought, representing about 1% of the flux of large bolides. The inferred bulk physical properties suggest that the interstellar medium could bias these projectiles toward high strength rocks with the ability to survive prolonged exposure to the harsh interstellar space conditions.
Journal Article
Impact : how rocks from space led to life, culture, and Donkey Kong
A noted meteoriticist shows how meteorites have helped build our planet and influenced humanity since the start of civilization.
Book
Modeling the 2022 τ-Herculid Outburst
The τ-Herculids (IAU shower number 61 TAH) is a minor meteor shower associated with comet 73P/Schwassmann–Wachmann 3, a Jupiter-family comet that disintegrated into several fragments in 1995. As a consequence of the nucleus breakup, possible increased meteor rates were predicted for 2022. On May 30–31, observation networks around the world reported two distinct peaks of TAH activity, around solar longitudes 69.°02 and 69.°42. This work examines the encounter conditions of the Earth with meteoroids ejected from 73P during the splitting event and on previous perihelion passages. Numerical simulations suggest that the main peak observed in 2022 was caused by meteoroids ejected from the splitting nucleus with four times the typical cometary gas expansion speed. High-resolution measurements performed with the Canadian Automated Meteor Observatory indicate that these meteoroids are fragile, with estimated bulk densities of 250 kg m−3. In contrast with the main peak, the first TAH activity peak in 2022 is best modeled with trails ejected prior to 1960. We find that ordinary cometary activity could have produced other TAH apparitions observed in the past, including in 1930 and 2017. The extension of our model to future years predicts significant returns of the shower in 2033 and 2049.
Journal Article
Meteoroid Stream Identification with HDBSCAN Unsupervised Clustering Algorithm
Accurate identification of meteoroid streams is central to understanding their origins and evolution. However, overlapping clusters and background noise hinder classification, an issue amplified for missions such as the European Space Agency’s Lunar Meteoroid Impact Observer that rely on meteor shower observations to infer lunar meteoroid impact parameters. This study evaluates the performance of the Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) algorithm for unsupervised meteoroid stream identification, comparing its outcomes with the established Cameras for All-Sky Meteor Surveillance (CAMS) look-up table method. We analyze the CAMS Meteoroid Orbit Database v3.0 using three feature vectors: LUTAB (CAMS geocentric parameters), ORBIT (heliocentric orbital elements), and GEO (adapted geocentric parameters). HDBSCAN is applied with varying minimum cluster sizes and two cluster selection methods (eom and leaf). To align HDBSCAN clusters with CAMS classifications, the Hungarian algorithm determines the optimal mapping. Clustering performance is assessed via the Silhouette score, Normalized Mutual Information, and F1 score, with Principal Component Analysis further supporting the analysis. With the GEO vector, HDBSCAN confirms 39 meteoroid streams, 21 strongly aligning with CAMS. The ORBIT vector identifies 30 streams, 13 with high matching scores. Less active showers pose identification challenges. The eom method consistently yields superior performance and agreement with CAMS. Although HDBSCAN requires careful selection of the minimum cluster size, it delivers robust, internally consistent clusters and outperforms the look-up table method in statistical coherence. These results underscore HDBSCAN’s potential as a mathematically consistent alternative for meteoroid stream identification, although further validation is needed to assess physical validity.
Journal Article
Search for the True Parent Body of the Phoenicid Meteor Shower
In 2024, Ďurišová et al. found that the meteor shower Phoenicids, IAU No. 254, code PHO, can originate in the nuclei of three comets, 46P/Wirtanen, 104P/Kowal 2, and 289P/Blanpain. The latter was suggested to be the parent body of the shower already in 1963 by Ridley. In this work, we model the meteoroid streams of all three comets and follow their dynamical evolution in course to reveal, which of the three comets is dynamically the most suitable parent body and if there is only a single parent or the stream might be fed with the particles released from more objects. It is a difficult task not only because these comets and particles released from them show an erratic dynamical evolution, but also because the Phoenicid shower is, according to the IAU Meteor Data Center List of Showers, currently represented by two significantly different solutions. We concluded that all three comets can contribute with the meteoroids to the Phoenicid stream. The dynamics of 289P’s stream is mostly appropriate to fit the Phoenicid-shower solution AdNo = 1, but the nucleus of this comet is too small to explain the estimated total mass of the stream. The Phoenicids either occurred due to some sudden, but short term outbursts of the particles from the 289P’s nucleus or the other two comets, especially 46P, are the further parent bodies. Our study also indicates that the recently discovered shower M2023-Y1 is most probably the third solution of the Phoenicids.
Journal Article
WISE/NEOWISE Multiepoch Imaging of the Potentially Geminid-related Asteroids: (3200) Phaethon, 2005 UD, and 1999 YC
We present space-based thermal infrared observations of the presumably Geminid-associated asteroids: (3200) Phaethon, 2005 UD, and 1999 YC using Wide-field Infrared Survey Explorer/Near-Earth Object WISE. The images were taken at the four wavelength bands 3.4 μm (W1), 4.6 μm (W2), 12 μm (W3), and 22 μm (W4). We find no evidence of lasting mass loss in the asteroids over the decadal multiepoch data sets. We set an upper limit to the mass-loss rate in dust of Q dust ≲ 2 kg s−1 for Phaethon and ≲0.1 kg s−1 for both 2005 UD and 1999 YC, respectively, with little dependency over the observed heliocentric distances of R h = 1.0–2.3 au. For Phaethon, even if the maximum mass loss was sustained over the 1000(s) yr dynamical age of the Geminid stream, it is more than two orders of magnitude too small to supply the reported stream mass (1013–14 kg). The Phaethon-associated dust trail (Geminid stream) is not detected at R h = 2.3 au, corresponding to an upper limit on the optical depth of τ < 7 × 10−9. Additionally, no comoving asteroids with radii r e < 650 m were found. The DESTINY+ dust analyzer would be capable of detecting several of the 10 μm sized interplanetary dust particles when at far distances (≳50,000 km) from Phaethon. From 2005 UD, if the mass-loss rate lasted over the 10,000 yr dynamical age of the Daytime Sextantid meteoroid stream, the mass of the stream would be ∼1010 kg. The 1999 YC images showed neither the related dust trail (the optical depth τ < 2 × 10−8) nor comoving objects with radii r e < 170 m at R h = 1.6 au. Estimated physical parameters from these limits do not explain the production mechanism of the Geminid meteoroid stream. Lastly, to explore the origin of the Geminids, we discuss the implications for our data in relation to the possibly sodium-driven perihelion activity of Phaethon.
Journal Article
A Comparison of Geminid Models with the PSP/WISPR-observed Phaethon Dust Trail
White-light observations from the Wide-Field Imager for Parker Solar Probe (WISPR) instrument on NASA’s Parker Solar Probe recently revealed the presence of a narrow, dense dust trail close to the orbit of asteroid 3200 Phaethon. Although Geminid related, it aligns imperfectly with Phaethon’s orbit and known Geminid meteoroid orbits. To address the nature of this dust trail, we performed a detailed comparison between the WISPR trail observations and several well-developed Geminid models. Simulating these models in the WISPR field of view visually demonstrates that the WISPR trail almost certainly represents the true “density core” of the Geminid stream. Trends in model trail width and offset from Phaethon’s orbit, both as functions of true anomaly, agree with observations to varying extents. All the models, however, place their apparent core interior to the parent orbit due to Poynting–Robertson forces, contradictory to the WISPR trail, which is exterior to Phaethon’s orbit. Therefore, Phaethon’s current orbit likely does not represent the orbit of the system parent, which most probably had a larger semimajor axis. These findings provide new initial conditions for future Geminid models, with WISPR identifying the Geminid core’s position.
Journal Article
A Search for Meteoroid Streams and Their Sources in the Near-Sun Zodiacal Dust Cloud
The structure and dynamics of the zodiacal cloud close to the Sun may be significantly influenced by the interaction between a background quasihomogeneous zodiacal cloud and discrete meteoroid streams associated with small bodies like comets and asteroids. The extent of this influence depends upon how many such streams exist and the mechanisms by which they modify the near-Sun zodiacal cloud. This study compares in situ dust detection data in near-Sun solar wind against predictions made by a simplified zodiacal dust cloud model to search for small-scale meteoroid stream structures. A strong localized departure from the model is found. A small number of asteroids and comets have been identified that have orbits appropriate to produce the observed departure from the model through either direct meteoroid stream detection or through enhanced β-meteoroid production. These observations suggest that discrete meteoroid streams may be common in the inner zodiacal cloud and therefore may be important for its structure and dynamics.
Journal Article
Current Knowledge of Objects Approaching the Earth
Modern ideas about objects approaching the Earth are discussed. This population includes near-Earth asteroids (NEAs), including potentially hazardous asteroids, short-period comets, meteoroid streams, and large sporadic meteoroids. An overview is given of the currently available information on the dynamic and physical properties of NEAs and comets. Almost 5% of the currently known NEAs are extinct cometary nuclei or their fragments. Being outwardly similar with true asteroids, they differ markedly in their dynamic and physical properties. In order to distinguish between these groups of objects, it is necessary to study both their dynamic and physical parameters. Some of the known meteoroid streams are shown to contain, along with the countless small meteoroids, also large extinct fragments of cometary nuclei, which are classified as NEAs. A meteoroid stream and such bodies belonging to it form together an asteroid–meteoroid complex. Observational and theoretical data are presented to confirm the modern understanding of near-Earth objects.
Journal Article