Meteor Streams Research Articles

Electrostatic dust ejection from asteroid (3200) Phaethon with the aid of mobile alkali ions at perihelion

The asteroid (3200) Phaethon is known to be the parent body of the Geminids, although meteor showers are commonly associated with the activity of periodic comets. What is most peculiar to the asteroid is its comet-like activity in the ejection of micrometer-sized dust particles at every perihelion passage, while the activity of the asteroid has never been identified outside the near-perihelion zone at 0.14au from the Sun. From the theoretical point of view, we argue that the activity of the asteroid is well explained by the electrostatic lofting of micrometer-sized dust particles with the aid of mobile alkali ions at high temperatures. The mass-loss rates of micrometer-sized particles from the asteroid in our model is entirely consistent with the values inferred from visible observations of Phaethon’s dust tail. For millimeter-sized particles, we predict three orders of magnitudes higher mass-loss rates, which could also account for the total mass of the Geminid meteoroid stream by the electrostatic lofting mechanism.

The meteoroid stream of comet 109P/Swift-Tuttle, Perseids, and further related meteor showers

The meteoroid stream of comet 109P/Swift-Tuttle, the well-known parent body of the Perseids, #7, is studied. The meteoroids released from the comet’s surface more than about 20kyr ago evolved to orbits similar to the mean orbits of 49 Andromedids, #549, and, possibly, also of the o-Aurigids, #696. These showers are similar to the Perseids and can be regarded as Perseid sub-structures. Interestingly, the modeled, as well as the real, o-Aurigids have a smaller perihelion distance. If they are regarded as a sub-structure of the Perseids, then we can speak about the bimodal structure of this major shower. Some meteoroids of the 109P’s stream, which could evolve over a longer period than about 40kyr, moved into the orbits on which they approach the Earth from the southern sky. They constitute a further shower related to 109P, the o-Hydrids, #569. We found an indication that the January β-Craterids, #582, moving in orbits similar to the o-Hydrids, could also be related to the comet. The radiant areas of the Perseids, 49 Andromedids and o-Aurigids are symmetrical to the radiant areas of the o-Hydrids and January β-Craterids in respect to the apex of the Earth’s heliocentric motion.

The impact hazard of near-Sun comets

ABSTRACT There are several groups of comets with perihelion near the solar surface known. Of these, the Marsden and Kracht groups move in orbits situated in a spatial corridor of the daytime Arietid meteoroid stream. The orbits of comets of the Meyer group are not very different from those of the Marsden and Kracht groups; for the purpose of our study, we thus consider a common Meyer–Marsden–Kracht (MMK) group. Since Arietids pass close to the Earth’s orbit, comets of the MMK group must also do so. We study the close approaches of the orbits of these comets with regard to the proximity of the orbit of our planet and estimate an impact hazard. We found a concentration of approaches within an interval of solar longitude from ∼72○–84○ (between June 2 and June 15). The mean time between two collisions of an MMK comet and Earth is estimated to be one to two million years, assuming a steady state during that period.

Mass Indices of Meteoric Bodies: II. Evolution of Meteoroid Streams

Mass Indices of Meteoric Bodies: II. Evolution of Meteoroid Streams

Mass Indices of Meteoric Bodies: I. Formation Model of Meteoroid Streams

Mass Indices of Meteoric Bodies: I. Formation Model of Meteoroid Streams

On mean motion resonances in the Geminid meteoroid stream

Analysing numerical models of the Geminid meteoroid stream for particle masses 0.00003–0.3 ​g we found evidence of several mean motion resonances: 1:2, 2:5, 3:7, 3:8 and 4:9 with Venus, 2:3 and 5:7 with the Earth and 7:1 with Jupiter. The resonant particles form dust trails located far from the Earth's orbit. Indeed, there is no observational support for resonant effects in the observed Geminid meteor shower. The trails are stable and compact, and consist of large (0.003–0.3 ​g) meteoroids.

Learning about comets from the study of mass distributions and fluxes of meteoroid streams

ABSTRACT Meteor physics can provide new clues about the size, structure, and density of cometary disintegration products, establishing a bridge between different research fields. From meteor magnitude data we have estimated the mass distribution of meteoroids from different cometary streams by using the relation between the luminosity and the mass obtained by Verniani. These mass distributions are in the range observed for dust particles released from comets 1P/Halley and 81P/Wild 2 as measured from spacecraft. From the derived mass distributions, we have integrated the incoming mass for the most significant meteor showers. By comparing the mass of the collected interplanetary dust particles (IDPs) with that derived for cometary meteoroids a gap of several orders of magnitude is encountered. The largest examples of fluffy particles are clusters of IDPs no larger than 100 μm in size (or 5 × 10–7 g in mass) while the largest cometary meteoroids are centimeter-sized objects. Such gaps can be explained by the fragmentation in the atmosphere of the original cometary particles. As an application of the mass distribution computations we describe the significance of the disruption of fragile comets in close approaches to Earth as a more efficient (and probably more frequent) way to deliver volatiles than direct impacts. We finally apply our model to quantify the flux of meteoroids from different meteoroid streams, and to describe the main physical processes contributing to the progressive decay of cometary meteoroids in the interplanetary medium.

Collisional Evolution of the Inner Zodiacal Cloud

Abstract The zodiacal cloud is one of the largest structures in the solar system and strongly governed by meteoroid collisions near the Sun. Collisional erosion occurs throughout the zodiacal cloud, yet it is historically difficult to directly measure and has never been observed for discrete meteoroid streams. After six orbits with Parker Solar Probe (PSP), its dust impact rates are consistent with at least three distinct populations: bound zodiacal dust grains on elliptic orbits (α-meteoroids), unbound β-meteoroids on hyperbolic orbits, and a third population of impactors that may be either direct observations of discrete meteoroid streams or their collisional by-products (“β-streams”). The β-stream from the Geminids meteoroid stream is a favorable candidate for the third impactor population. β-streams of varying intensities are expected to be produced by all meteoroid streams, particularly in the inner solar system, and are a universal phenomenon in all exozodiacal disks. We find the majority of collisional erosion of the zodiacal cloud occurs in the range of 10–20 solar radii and expect this region to also produce the majority of pickup ions due to dust in the inner solar system. A zodiacal erosion rate of at least ∼100 kg s−1 and flux of β-meteoroids at 1 au of (0.4–0.8) × 10−4 m−2 s−1 are found to be consistent with the observed impact rates. The β-meteoroids investigated here are not found to be primarily responsible for the inner source of pickup ions, suggesting nanograins susceptible to electromagnetic forces with radii below ∼50 nm are the inner source of pickup ions. We expect the peak deposited energy flux to PSP due to dust to increase in subsequent orbits, up to 7 times that experienced during its sixth orbit.

Dust Directionality and an Anomalous Interplanetary Dust Population Detected by the Parker Solar Probe

Abstract Theory and previous space missions indicate there are several populations of zodiacal dust. The most prominent populations are grains on bound elliptic orbits (α-meteoroids), and β-meteoroids on hyperbolic escape trajectories governed largely by their size and composition. Yet, there may be other populations not yet confirmed by observation. The Parker Solar Probe (PSP) spacecraft is able to observe in situ dust populations in the densest part of the zodiacal cloud. Over the first seven orbits, dust count rates are well organized by orbital groups based on orbital parameters of PSP’s shrinking orbit. In particular, the first three orbits and the sixth orbit have a single, preperihelion peak in count rate with a gradual drop off postperihelion, while Orbits 4, 5, and 7 have two distinct count rate peaks on either side of perihelion. The secondary peaks in Orbits 4, 5, and 7 are inconsistent with current zodiacal dust models that account for only two dust populations: α- and β-meteoroids. In examining the directionality of dust impacts on the PSP spacecraft, the presence of an anti-ram impactor anomaly postperihelion during Orbit 4 is evident. This anomaly may indicate another dust population beyond the nominal α- and β-meteoroids, and its origin may be related to the Geminids meteoroid stream associated with the asteroid 3200 Phaethon.

Bennu's Natural Sample Delivery Mechanism: Estimating the Flux of Bennuid Meteors at Earth

AbstractNASA's OSIRIS‐REx mission observed millimeter‐ to centimeter‐scale pebbles being ejected from the surface of asteroid (101955) Bennu, indicating that Bennu is an active asteroid. About 30% of these particles escape from Bennu, and the minimum orbital intersection distance (MOID) between Bennu and Earth suggest the possibility of a “Bennuid” particle flux at Earth. We characterize the evolution of Bennu's particle stream and potential for meteor flux by simulating weekly particle ejections between the years 1780 and 2135 continuing their dynamical evolution until 2200. Ejections are modeled as a discrete release of 95 particles every week. The meteoroid stream is found to be fully distributed around Bennu's orbital path in years. Individual particles and streams remain associable to Bennu for the entire 420 years simulated. Particle flux at Earth is predicted to begin in 2101, as the Bennu‐Earth MOID reaches minimum values. The year of highest particle flux, 2182, experiences 161 Earth intersections and accounts for 1/4 of our predicted meteors. Our methods can be expanded to study the history and structure of the general meteoroid population and to estimate flux from specific near‐Earth asteroids.

The Geminid meteor shower radiant: a mathematical model

ABSTRACT The origin of the Geminid meteoroid stream and its parent body the asteroid (3200) Phaethon is still under discussion. The observed bimodal activity profile of the Geminid shower agrees with a cometary scheme of the stream formation. We show that the radiant areas for meteors of different magnitudes may also be used to provide arguments supporting or undermining the cometary hypothesis. We used semi-analytic and numerical models of the stream. The resulting model radiants for meteors of various magnitudes (masses) have peculiar patterns that might be detected in a real shower.

Luminous efficiency of meteors derived from ablation model after assessment of its range of validity

Context.The luminous efficiency,τ, can be used to compute the pre-atmospheric masses of meteoroids from corresponding recorded meteor brightnesses. The derivation of the luminous efficiency is non-trivial and is subject to biases and model assumptions. This has led to greatly varying results in the last decades of studies.Aims.The present paper aims to investigate how a reduction in various observational biases can be achieved to derive (more) reliable values for the luminous efficiency.Methods.A total of 281 meteors observed by the Fireball Recovery and InterPlanetary Observation Network (FRIPON) are studied. The luminous efficiencies of the events are computed using an ablation-based model. The relations ofτas a function of the pre-atmospheric meteoroid velocity,ve, and mass,Me, are studied. Various aspects that could render the method less valid, cause inaccuracies, or bias the results are investigated. On this basis, the best suitable meteors were selected for luminous efficiency computations.Results.The presented analysis shows the limits of the used method. The most influential characteristics that are necessary for reliable results for theτcomputation were identified. We study the dependence ofτon the assumed meteoroid’s density,ρ, and include improvedρ-values for objects with identified meteoroid stream association. Based on the discovered individual biases and constraints we create a pre-debiased subset of 54 well-recorded events with a relative velocity change >80%, a final height <70 km, and a Knudsen number Kn < 0.01; this last value indicates that the events were observed in the continuum-flow regime. We findτ-values in the range between 0.012% and 1.1% for this pre-debiased subset and relations ofτtoveandMeof:τ=7.33⋅ve−1.10andτ=0.28⋅Me−0.33.Conclusions.The derived luminous efficiency of meteoroids depends on the assumed material density. Our results indicate that the applied debiasing method improves the analysis ofτfrom decelerated meteoroids. The underlying method is only valid for meteors in the continuum-flow regime. These events tend to have low end heights, large masses, and high deceleration.

Meteoroid Stream of Comet C/1961 T1 (Seki) and Its Relation to the December ρ-Virginids and γ-Sagittariids

Abstract We answer the question of whether long-period comet C/1961 T1 (Seki) is the parent body of a meteor shower observed in Earth’s atmosphere. We model discrete parts of a meteoroid stream associated with this comet and follow the orbital evolution of its particles via a numerical integration of their orbits. The gravitational perturbations of major planets and the Poynting–Robertson effect, which influences the motion of the particles, are taken into account. We predict two showers which are related to C/1961 T1. One of these showers was identified with the December ρ-Virginids, #502. This identification confirms an earlier suggested relationship between the shower and the comet. The second predicted shower was identified with the γ-Sagittariids, #657. The radiant areas of both showers are symmetrical in respect to the apex of Earth’s heliocentric motion.

Modeling the meteoroid streams of comet C/1861 G1 (Thatcher), Lyrids

The meteoroid stream of long-period comet C/1861 G1 (Thatcher) is modeled in course to reveal the details of its structure. Specifically, we modeled several parts of the comet's theoretical stream, which were characterized by various values of evolutionary times and various strengths of the Poynting-Robertson effect. The dynamical behaviour of 10 ​000 test particles in each model from the time of their ejection up to the present was followed via a numerical integration of their orbits. The characteristics of the particles that moved on orbits approaching the Earth's orbit were used to predict a shower. Primarily, we wanted to find whether C/1861 G1 is the parent body of other meteor showers than the April Lyrids. However, we confirm that the orbit of this parent and its meteoroid stream is relatively stable during a long time and the meteoroids can collide with our planet only in the pre-perihelion orbital arc corresponding to the April Lyrids, No. 6, code LYR. Our modeling did not show any clustering of the meteoroids in the stream due to the gravitational perturbations that could explain the observed outbursts. The observed semi-major axes are, in general, smaller than those of the modeled particles and the parent comet because of a selection effect. Namely, the meteoroids in orbits with smaller semi-major axes pass the Earth's orbit more frequently. They are then observed and recorded in the data more often than the meteors with the larger axes.

Dynamical evolution and thermal history of asteroids (3200) Phaethon and (155140) 2005 UD

The near-Earth objects (NEOs) (3200) Phaethon and (155140) 2005 UD are thought to share a common origin, with the former exhibiting dust activity at perihelion that is thought to directly supply the Geminid meteor stream. Both of these objects currently have very small perihelion distances (0.140au and 0.163au for Phaethon and 2005 UD, respectively), which results in them having perihelion temperatures around 1000K. A comparison between NEO population models to discovery statistics suggests that low-perihelion objects are destroyed over time by a, possibly temperature-dependent, mechanism that is efficient at heliocentric distances less than 0.3au. By implication, the current activity from Phaethon is linked to the destruction mechanism of NEOs close to the Sun.We model the past thermal characteristics of Phaethon and 2005 UD using a combination of a thermophysical model (TPM) and orbital integrations of each object. Temperature characteristics such as maximum daily temperature, maximum thermal gradient, and temperature at different depths are extracted from the model, which is run for a predefined set of semi-major axis and eccentricity values. Next, dynamical integrations of orbital clones of Phaethon and 2005 UD are used to estimate the past orbital elements of each object. These dynamical results are then combined with the temperature characteristics to model the past evolution of thermal characteristics such as maximum (and minimum) surface temperature and thermal gradient. The orbital histories of Phaethon and 2005 UD are characterized by cyclic changes in e, resulting in perihelia values periodically shifting between present-day values and 0.3au. Currently, Phaethon is experiencing relatively large degrees of heating when compared to the recent 20,000yr. We find that the subsurface temperatures are too large over this timescale for water ice to be stable, unless actively supplied somehow. The near-surface thermal gradients strongly suggest that thermal fracturing may be very effective at breaking down and ejecting dust particles. Observations by the DESTINY+ flyby mission will provide important constraints on the mechanics of dust-loss from Phaethon and, potentially, reveal signs of activity from 2005 UD.In addition to simulating the recent dynamical evolution of these objects, we use orbital integrations that start from the Main Belt to assess their early dynamical evolution (origin and delivery mechanism). We find that dwarf planet (2) Pallas is unlikely to be the parent body for Phaethon and 2005 UD, and it is more likely that the source is in the inner part of the asteroid belt in the families of, e.g., (329) Svea or (142) Polana.

Modelling cometary meteoroid stream traverses of the Martian Moons eXploration (MMX) spacecraft en route to Phobos

The Martian Moons Exploration (MMX) spacecraft is a JAXA mission to Mars and its moons Phobos and Deimos. MMX will be equipped with the Circum-Martian Dust Monitor (CMDM) which is a newly developed light-weight (mathrm {650,g}) large area (1,mathrm {m}^{2}) dust impact detector. Cometary meteoroid streams (also referred to as trails) exist along the orbits of comets, forming fine structures of the interplanetary dust cloud. The streams consist predominantly of the largest cometary particles (with sizes of approximately 100,mu mathrm { m} to 1 cm) which are ejected at low speeds and remain very close to the comet orbit for several revolutions around the Sun. The Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model is a new and recently published universal model for cometary meteoroid streams in the inner Solar System. We use IMEX to study the detection conditions of cometary dust stream particles with CMDM during the MMX mission in the time period 2024 to 2028. The model predicts traverses of 12 cometary meteoroid streams with fluxes of 100,mu mathrm { m} and bigger particles of at least 10^{-3},mathrm {m}^{-2},mathrm {day}^{-1} during a total time period of approximately 90 days. The highest flux of 0.15,mathrm {m}^{-2},mathrm {day}^{-1} is predicted for comet 114P/Wiseman-Skiff in October 2026. With its large detection area and high sensitivity CMDM will be able to detect cometary meteoroid streams en route to Phobos. Our simulation results for the Mars orbital phase of MMX also predict the occurrence of meteor showers in the Martian atmosphere which may be observable from the Martian surface with cameras on board landers or rovers. Finally, the IMEX model can be used to study the impact hazards imposed by meteoroid impacts onto large-area spacecraft structures that will be particularly necessary for crewed deep space missions.

The Space of Keplerian Orbits and a Family of Its Quotient Spaces

The distance functions on the set of Keplerian orbits play an important role in solving the problems of searching for the parent bodies of meteoroid streams. A special kind of function is the distances in the quotient spaces of orbits. Three metrics of this type were developed earlier. These metrics allow disregarding the longitude of the ascending node or the argument of pericenter, or both. Here, we introduce one more quotient space, where two orbits are considered to be identical if they differ only in their longitudes of nodes and arguments of pericenters, but have the same sum of these elements (the longitude of pericenter). Function $${{\varrho }_{6}}$$ is defined to calculate the distance between two equivalence classes of orbits. The algorithm for calculation of $${{\varrho }_{6}}$$ from given elements of the orbits is provided along with a reference to the corresponding program written in the C++ programming language. Unfortunately, function $${{\varrho }_{6}}$$ is not a full-fledged metric. We have proven that it satisfies the first two axioms of a metric space; however, it does not satisfy the third axiom: the triangle inequality does not hold, at least in the case of large eccentricities. However, there are two important cases when the triangle axiom is satisfied: one of three orbits is circular and the longitudes of pericenters of all three orbits coincide. Perhaps, the inequality holds for all elliptic orbits, but this is a matter of further research.

A Deep Search for Emission from “Rock Comet” (3200) Phaethon at 1 au

Abstract We present a deep imaging and spectroscopic search for emission from (3200) Phaethon, a large near-Earth asteroid that appears to be the parent of the strong Geminid meteoroid stream, using the 4.3 m Lowell Discovery Telescope. Observations were conducted on 2017 December 14–18 when Phaethon passed only 0.07 au from the Earth. We determine the 3σ upper level of dust and CN production rates to be 0.007–0.2 kg s−1 and 2.3 × 1022 molecules s−1 through narrowband imaging. A search in broadband images taken through the SDSS r′ filter shows no 100 m class fragments in Phaethon’s vicinity. A deeper but star-contaminated search also shows no sign of fragments down to 15 m. Optical spectroscopy of Phaethon and comet C/2017 O1 (ASASSN) as a comparison confirms the absence of cometary emission lines from Phaethon and yields 3σ upper levels of CN, C2, and C3 of ∼1024–1025 molecules s−1, 2 orders of magnitude higher than the CN constraint placed by narrowband imaging, due to the much narrower on-sky aperture of the spectrographic slit. We show that narrowband imaging could provide an efficient way to look for weak gas emission from near-extinct bodies near the Earth, though these observations require careful interpretation. Assuming Phaethon’s behavior is unchanged, our analysis shows that the DESTINY+ mission, currently planning to explore Phaethon in 2026, may not be able to directly detect a gas coma.

The space of Keplerian orbits and a family of its quotient spaces

Distance functions on the set of Keplerian orbits play an important role in solving problems of searching for parent bodies of meteoroid streams. A special kind of such functions are distances in the quotient spaces of orbits. Three metrics of this type were developed earlier. These metrics allow to disregard the longitude of ascending node or the argument of pericenter or both. Here we introduce one more quotient space, where two orbits are considered identical if they differ only in their longitudes of nodes and arguments of pericenters, but have the same sum of these elements (the longitude of pericenter). The function q is defined to calculate distance between two equivalence classes of orbits. The algorithm for calculation of ̺6 value is provided along with a reference to the corresponding program, written in C++ language. Unfortunately, ̺6 is not a full-fledged metric. We proved that it satisfies first two axioms of metric space, but not the third one: the triangle inequality does not hold, at least in the case of large eccentricities. However there are two important particular cases when the triangle axiom is satisfied: one of three orbits is circular, longitudes of pericenters of all three orbits coincide. Perhaps the inequality holds for all elliptic orbits, but this is a matter of future research.

Modeling the meteoroid streams of comets C/1894 G1 (Gale) and C/1936 O1 (Kaho-Kozik-Lis)

We modeled meteoroid streams of two long-period comets, C/1894 G1 (Gale) and C/1936 O1 (Kaho-Kozik-Lis), in order to reveal their possible associations with meteor showers observed in the Earth’s atmosphere. For both comets, we modeled several parts of their theoretical streams, characterized by various values of evolutionary times and various strengths of the Poynting-Robertson effect. We studied the dynamical behaviour of 10000 test particles in each model from the time of their ejection up to the present. The characteristics of the particles that moved on orbits approaching the Earth’s orbit were used to predict showers which are related to the parent comet. We also mapped the impacts of possibly different cometary orbits on our predictions by creating models of the streams based on several cloned orbits.The modeling of the stream of the comet C/1894 G1 led to a prediction of a single shower related to the comet. Its existence was, however, not confirmed by real meteor data. Nevertheless, as a byproduct of our investigation, we found a new meteor shower in three databases of video meteors. In line with our suggestion, the shower was named the December ι-Ursae Majorids, No. 1049 and code DIU. We do not consider it as related to the comet.The stream models of the C/1936 O1 also yielded a single predicted shower. Its identification was, in this case, successful and also supported by the cloned-orbit models. In two datasets, we found a shower with characteristics consistent with the predictions. After our suggestion, the shower was newly added into the IAU MDC list as the January ψ-Scorpiids, No. 1048, code JAS.