Meteor Showers Research Articles

How Meteor Showers Can Guide the Search for Long-period Comets

With orbital periods longer than 200 yr, most long-period comets (LPCs) remain undiscovered until they are in-bound toward perihelion. The comets that pass close to Earth’s orbit are potentially hazardous objects. Those with orbital periods up to ∼4000 yr tend to have passed close to Earth’s orbit in a previous orbit and produced a meteoroid stream dense enough to be detected at Earth as a meteor shower. In anticipation of Rubin Observatory’s Legacy Survey of Space and Time (LSST), we investigate how these meteor showers can guide dedicated searches for their parent comets. Assuming search parameters informed by LSST, we calculated where the 17 known parent bodies of LPC meteor showers would have been discovered based on a cloud of synthetic comets generated from the shower properties as measured at Earth. We find that the synthetic comets predict the on-sky location of the parent comets at the time of their discovery. The parent comet’s location on average would have been 1.°51 ± 1.°19 from a line fit through the synthetic comet cloud. The difference between the heliocentric distance of the parent and mean heliocentric distance of synthetic comets on the line was 2.09 ± 1.89 au for comets with unknown absolute nuclear magnitudes and 0.96 ± 0.80 au for comets with known absolute nuclear magnitudes. We applied this method to the σ-Hydrids, the proposed meteor shower of comet Nishimura, and found that it successfully matched the pre-covery location of this comet 8 months prior to Nishimura’s discovery.

Near-Earth Asteroids as the parents of the $\delta$-Cancrid Meteoroid Stream

Abstract The $\delta$-Cancrid meteoroid stream forms four active meteor showers which are observable on the Earth annually during January-February and August-September. The stream's definite parent comet has not been established. We performed a search for near-Earth
 asteroids (NEAs) associated with this stream. We have followed the backward evolution of the orbital elements of a sample of NEAs and found their orbits at the Earth-crossing positions. Using these orbits, we calculated the theoretical parameters of meteor showers
 associated with the considered NEAs. We carried out our search for observable active showers that match theoretically predicted ones with published data, and the result turned out that the predicted meteor showers of 13 NEAs were identified with the active showers produced by the $\delta$-Cancrid meteoroid stream. The comet-like orbits of NEAs and established association with active meteor showers indicate their common cometary origin. The NEAs considered are moving within the stream and likely represent the dormant remnants of a parent comet of the $\delta$-Cancrid asteroid-meteoroid complex disintegrated more than 12 thousand years
 ago.

Diurnal and Seasonal Variations of Meteor Speed and Arrival Angle Observed by Mengcheng Meteor Radar

AbstractMeteor speed is crucial in identifying key astronomical aspects of the meteoroid environment, including the influx of meteoric material and the distribution of meteoric radiants. This study investigates diurnal and seasonal variations of meteor speed from April 2014 to December 2023 observed by the Mengcheng meteor radar (MCMR; 33.4°N, 116.3°E). In addition to the expected diurnal variation of meteor speed, azimuth peak, zenith peak, and the azimuthal direction of maximum meteor speed due to the Earth's rotation, where the meteor speed peaks northward in the local morning and shifts clockwise, we find that the meteor speed distribution resembles a superposition of two Gaussian distributions, with the lower (higher) distribution mainly ranging from 20 to 40 (45–65) km/s. The two speed peaks are estimated using a double‐Gaussian fitting approach. In terms of seasonal variation, we find that (a) the low‐speed peak indicates a semi‐annual variation cycle, with maxima in June–July and December–January, and minima in February and August; (b) the high‐speed peak indicates an annual variation cycle, with maxima in September–December and minima in March. There is also a correlation between the seasonal variations in the meteor speed peaks and the occurrence of meteor showers. Statistical analysis provides a map of seasonal variations in the intensity, duration, and timing of meteor shower activities, which is supplemental to previous shorter‐duration studies using backscatter meteor radar observations. We also find notable shower events where the meteor counts exceed 45%–97% of the background count on corresponding event dates and speeds.

Rekonstruksi Kalimat pada Teks Berita di Laman CNN Indonesia Edisi Desember 2023 sebagai Bahan Ajar Membaca Kritis Siswa Kelas 12 SMA

News is a text that has an important role in disseminating information. News text is so useful that it has become a literacy material for students due to the development of advanced technology. Although it has become one of the sources of student literacy, online news texts are still classified as having syntactic errors such as a lack of understanding of the language used in compiling a sentence in the news. The purpose of this study is to describe sentence errors in the news contained in the old CNN Indonesia news, such as "December Sky Phenomena: Geminid Meteor Shower to Solstice", "Mandalika Circuit's Important Role in Bringing Indonesian Drivers to Success in Asia", "Solar Storms Raining on Earth, RI Safe?", "The First Candidate Debate will be Held at the KPU Office on December 12", and "When HIV Tests Become a Scary Scourge Because of People's Scorn". This research uses a descriptive method with a qualitative approach. The results of this study found several findings such as effective sentences, ineffective sentences, spelling errors according to EYD, errors in the use of diction, and sentences that are not clear to the reader. The most common error found in the five news articles is ineffective sentences. The benefit of this research is to provide knowledge insights in the form of understanding sentence writing systematically, which will be useful in improving understanding of authorship in news texts and preventing errors from occurring again in the same news so that it is worthy of being a literacy material for 12th grade high school students.

NEOROCKS color survey: Final results

Context. Near-Earth objects (NEOs) are the most accessible small Solar System bodies by both spacecrafts and ground-based telescopes. Close encounters of these objects with Earth represent opportunities to characterize their physical and mineralogical properties. They are also a constant threat to humanity due to possible impact events with Earth. In this context, the NEOROCKS project has been financed by the European Union’s Horizon 2020 research and innovation program. Aims. We present the final results on photometry of the NEOROCKS project, with the aim of extending the dataset of surface colors for small NEOs with unknown properties and, when possible, characterizing newly discovered NEOs. Methods. Photometric observations were performed using the 1.2 m telescope at the Haute-Provence observatory (in France) in the BVRI filters of the Johnson-Cousins photometric systems between May 2022 and June 2023. The stability and dynamics of objects from the NEOROCKS database was investigated by numerical integration. Results. We obtained new surface colors for 83 NEOs. Overall, the NEOROCKS color database contains 170 objects. The majority of the objects in the dataset with diameters D<500 m belong to a group of silicate bodies. We estimated the unbalanced percentage between S- and C-type objects as an observational bias due to reflective proprieties of the surface of objects. The average of Lyapunov time of about 100 years is evidence of highly chaotic orbits of objects from the color database of NEOROCKS. Asteroid 2011 OL51 has a reasonable probability of being a parent body contributor to the October Capricornidis meteor shower. Asteroids 2004 HK33, 2022 VV (D-type), 2003 WR21, and 2017 SE1 (A-type) belong to end-member classes and have ΔV<7 km/s; thus, they are possible candidates for in situ investigations.

The threshold at which a meteor shower becomes hazardous to spacecraft

Although the risk posed to spacecraft due to meteoroid impacts is dominated by sporadic meteoroids, meteor showers can raise this risk for short periods of time. NASA’s Meteoroid Environment Office issues meteor shower forecasts that describe these periods of elevated risk, primarily for the purpose of helping plan extravehicular activities. These forecasts are constructed using a list of meteor shower parameters that has evolved over time to include newly discovered showers and incorporate improved measurements of their characteristics. However, at this point in time, more than a thousand meteor showers have been reported by researchers, many of which are extremely minor, are unconfirmed, or lack measurements of critical parameters. Thus, a comprehensive approach is no longer feasible. In this report we present a quantitative criterion for a potentially hazardous meteor shower and apply this criterion to the list of established meteor showers in order to determine which showers should be included in our annual forecasts.

On the Possible Astronomical Function of Portasar’s (G¨obekli Tepe) Pillar 27

The examination of Portasar’s Pillar 27 in Enclosure C from an archaeoastronomical point of view reveals four distinct directions. Considering the directions obtained as observational shows that they could have served to observe the simultaneous culminations of Pleiades, α Persei, and 36 Draconis pointing towards the North Ecliptic Pole during the activity period of the September ε-Perseid meteor shower. On the same day (perhaps a few days apart) before sunrise, it was most likely possible to observe the star disappearance of the constellations Hercules and Centaurus at their culmination points. At the same time, the T-shaped structure of Pillar 27 could serve as a shadow meter (gnomon) to show the specified day of the mentioned observations. Additionally, 36 days after the summer solstice (Perseids activity period), the simultaneous appearance of the stars β Andromedae and γ Draconis at their culmination points was observable. On the other hand, there are principal parallels with the possible observations with the help of Portasar’s Pillar 27 and the function of Platform 3 (as well as some angular stones (No. 7, 12, 158, etc.)) of the Zorats Qarer megalithic monument, which refer to the same millennium (9000 BC). There are also commonalities with ancient calendar patterns that relate to ancient mythological concepts. Their detailed analysis is still in progress.

Properties of outer solar system pebbles during planetesimal formation from meteor observations

Observations of proto-planetary disks, as well as theoretical modeling, suggest that in the late stages of accretion leading up to the formation of planetesimals, particles grew to pebbles the size of 1-mm to tens of cm, depending on the location and ambient conditions in the disk. That is the same size range that dominates the present-day comet and primitive asteroid mass loss. Meteoroids that size cause visible meteors on Earth. Here, we hypothesize that the size distribution and the physical and chemical properties of young meteoroid streams still contain information about the conditions in the solar nebula during these late stages of accretion towards planetesimal formation. If so, they constrain where long-period (Oort Cloud) comets, Jupiter-family (Scattered Disk Kuiper Belt) comets, and primitive asteroids (Asteroid Belt) formed. From video and visual observations of 47 young meteor showers, we find that freshly ejected meteoroids from long-period comets tend to have low bulk density and are distributed with equal surface area per log-mass interval (magnitude distribution index χ ∼ 1.85), suggesting gentle accretion conditions. Jupiter-family comets, on the other hand, mostly produce meteoroids twice as dense and distributed with a steeper χ ∼ 2.15 or even χ ∼ 2.5, which implies that those pebbles grew from particles fragmenting in a collisional cascade or by catastrophic collisions, respectively. Some primitive asteroids show χ > 2.5, with most mass in small particles, indicating an even more aggressive fragmentation by processes other than mutual collisions. Both comet populations contain an admixture of compact materials that are sometimes sodium-poor, but Jupiter-family comets show a higher percentage (∼8% on average) than long-period comet showers (∼4%) and a wider range of percentages among comets. While there are exceptions in both groups, the implication is that most long-period comets formed under gentle particle growth conditions, possibly near the 30 AU edge of the Trans Neptunian Disk, while most Jupiter family comets formed closer to the Sun where pebbles reached or passed the fragmentation barrier, and primitive asteroids formed in the region where the cores of the giant planets formed. This is possible if the Scattered Disk represents all objects scattered by Neptune during its migration, while the present-day outer Oort cloud formed only during and after the time of the planet instability, well after the Sun had moved away from sibling stars.

Radar observation of the new λ-Sculptorid meteor shower

Context. 46P/Wirtanen is a near-Earth comet (NEC) and several previous modeling works had predicted it would produce a meteor shower for the first time on December 12, 2023. Aims. We report the most comprehensive meteor radar observations of the λ-Sculptorid meteor shower produced by comet 46P/Wirtanen. These measurements are critical to constrain the mass distribution of the particles released by the comet as radars generally detect the smaller particle population of the shower. Methods. We utilized observations with the Southern Argentina Agile Meteor Radar-Orbital System (SAAMER-OS) ideally located in the southern hemisphere to detect this shower. Since the shower was predicted to produce very slow meteors, we used the same methodology applied for the Arid meteor shower. Results. As predicted, the shower peak was observed by SAAMER-OS on December 12, 2023 (λ0 = 259.73°) at 0900 UTC, with a Zenithal Hourly Rate (ZHR) peak value of ~2.5 m h−1. Most of the activity of the shower was observed during 2 h between 0730-0930 UTC. The observed mean radiant of the shower in Sun-centered ecliptic coordinates is located at λ − λ0 = 88.9° and β = −36.6°. Our results suggest that the particles detected by SAAMER-OS are in general larger than those for which thermal equilibrium can be assumed (>3 mg) in agreement with the conclusions of previous reports using video observations.

A Reference Meteor Magnitude for Intercomparable Fluxes

The rate at which meteors pass through Earth’s atmosphere has been measured or estimated many times over; existing flux measurements span at least 12 astronomical magnitudes, or roughly five decades in mass. Unfortunately, the common practice of scaling flux to a universal reference magnitude of +6.5 tends to collapse the magnitude or mass dimension. Furthermore, results from different observation networks can appear discrepant due solely to the use of different assumed population indices, and readers cannot resolve this discrepancy without access to magnitude data. We present an alternate choice of reference magnitude that is representative of the observed meteors and minimizes the dependence of flux on population index. We apply this choice to measurements of recent Orionid meteor shower fluxes to illustrate its usefulness for synthesizing independent flux measurements.

New and improved orbits of some historical comets: 6TH and 7TH centuries

Five comets from the 6th century and three from the 7th century are studied. In some cases, new orbital elements are provided, or existing ones are refined to better fit the observations. In addition, comments are presented on specific questions raised by other authors about these historical comets, such as their periodicity, association with meteor showers, or even their mere existence. We consider in particular the cases of C/539 W1 and 1P/607H1 (Halley), both particularly interesting from a historical point of view and for the questions they raise in this regard. Finally, we also examine the proposed membership of some 6th-century comets to the Kreutz Sungrazer group.

A generalizable method for estimating meteor shower false positives

Context. The determination of meteor shower or parent body associations is inherently a statistical problem. Traditional methods, primarily the similarity discriminants, have limitations, particularly in handling the increasing volume and complexity of meteoroid orbit data. Aims. We introduce a new more statistically robust and generalizable method for estimating false positive detections in meteor shower identification, leveraging kernel density estimation (KDE). The method is applied to fireball data from the European Fireball Network, a comprehensive photographic fireball observation network established in 1963 for the detailed monitoring and analysis of fireballs across central Europe Methods. Utilizing a dataset of 824 fireballs observed by the European Fireball Network, we applied a multivariate Gaussian kernel within KDE and Z-score data normalization. Our method analyzes the parameter space of meteoroid orbits and geocentric impact characteristics, focusing on four different similarity discriminants: DSH, D′, DH, and DN. Results. The KDE methodology consistently converges toward a true established shower-associated fireball rate within the EFN dataset of 18–25% for all criteria. This indicates that the approach provides a more statistically robust estimate of the shower-associated component. Conclusions. Our findings highlight the potential of KDE combined with appropriate data normalization in enhancing the accuracy and reliability of meteor shower analysis. This method addresses the existing challenges posed by traditional similarity discriminants and offers a versatile solution adaptable to varying datasets and parameters.

Recovering Data of an Observation of the Leonids in 1869 from the Lisbon Geophysical Observatory (Portugal)

The Leonid meteor shower is renowned for its scientific and public interest. In a search for meteorological data from Portuguese stations, records on an observation of the Leonids in 1869 from the Lisbon Geophysical Observatory “Infante Dom Luiz” were found. Given their potential value, a digital version with metadata is provided in the present note (the recovered data are available on doi:10.5281/zenodo.11221019). The observation took place from 9 PM on 1869 November 13 to 6 AM on November 14, local time in Lisbon, with mostly clear skies and 4–5 observers covering completely the sky. They recorded 1980 meteors, noting Zodiacal Light visibility and detailing meteor counts every five minutes.

Statistical equivalence of metrics for meteor dynamical association

Meteor showers, originating as a result of the activity of comets or the disruption of large objects, provide a unique window into the composition and dynamics of our Solar System. While modern meteor detection networks have amassed extensive data, distinguishing sporadic meteors from those belonging to specific meteor showers remains challenging. In this study, we statistically evaluate and compare four orbital similarity criteria within five-dimensional parameter space (DSH,DD,DH, and ϱ2) to study dynamical associations using the already classified meteors (manually by a human) in CAMS database as a benchmark. In addition, we assess various distance metrics typically used in Machine Learning with two different vectors: ORBIT, grounded in heliocentric orbital elements, and GEO, predicated on geocentric observational parameters. To estimate their degree of correlation and efficacy, the Kendall rank correlation coefficient and the Top-k accuracy are employed. The statistical equivalence of the Top-1 results is examined using the Kolmogorov–Smirnov test and the percentage of Top-1 agreement is calculated on an event-by-event basis. Additionally, we compute the optimal cut-offs for all methods for distinguishing sporadic background events. Our findings demonstrate the superior performance of the sEuclidean metric in conjunction with the GEO vector. Within the scope of D-criteria, DSH emerged as the preeminent metric, closely followed by ϱ2. The Bray-Curtis metric displayed an advantage compared to the other distance metrics when paired with the ORBIT vector for Top-k accuracy, however, the Cityblock metric is more effective when considering the sporadic background. ϱ2 stands out as the most equivalence to the distance metrics when utilizing the GEO vector and the most compatible with GEO and ORBIT simultaneously, whereas DD aligns more closely when using the ORBIT vector. The stark contrast in DD’s behavior compared to other D-criteria highlights potential inequivalence. Our results suggest that geocentric features provide a more robust basis than orbital elements for meteor dynamical association. Most distance metrics associated with the GEO vector surpass the D-criteria when differentiating the meteoroid background. Accuracy displayed a dependence on solar longitude with a pronounced decrease around 180° matching an apparent increase in the meteoroid background activity, tentatively associated with the transition from the Perseids to the Orionids. Considering lately identified meteor showers, ∼27% of meteors in CAMS would have different associations. This work unveils that Machine Learning distance metrics can rival or even exceed the performance of tailored orbital similarity criteria for meteor dynamical association.

Determining the population of large meteoroids in major meteor showers

We have estimated the largest meteoroids present in major meteor showers from observations conducted between 2019-2022 by the Geostationary Lightning Mapper (GLM) instrument on the GOES-R satellites. Our integrated time area products for the Leonids, Perseids and eta Aquariids are of order 5 × 1010 km2 hours. We compute photometric masses for shower fireballs using the approach of Vojáček et al. (2022) to correct from narrow-band GLM luminosity to bolometric luminosity and apply the luminous efficiency relation of Ceplecha & McCrosky (1976) at high speeds. Between 2019 and 2022, the showers definitely observed by GLM were the Leonids, Perseids, and eta Aquariids, with probable detections of the Orionids and Taurids. We find the largest meteoroids to be of order 7 kg for the Leonids, 3 kg for the Perseids, and 3 kg for the eta Aquariids, corresponding to meteoroids of ≈0.2 m diameter. The Orionids and Taurids had maximum meteoroid masses of 4 kg and 150 kg respectively. The Leonids and eta Aquariids are well fit by a single power-law with differential mass exponent, s, of 2.08 ± 0.08 and 2.00 ± 0.09 over the mass range 10−7< m < 1 kg. All showers had maximum meteoroid masses compatible with Whipple gas-drag ejection, with the exception of the Perseids which have much larger meteoroids than expected a result also consistent with observations from ground based instruments. This may reflect preferential ejection in narrow jets or possibly some form of mantle erosion/release in the past for the parent comet, 109P/Swift-Tuttle.

Analysis of the Dynamic Parameters of the Cancrids Meteor Shower and Its Drift Motion

Analysis of the Dynamic Parameters of the Cancrids Meteor Shower and Its Drift Motion

A statistical analysis of over three thousand meteors and their spectra

ABSTRACT In this article, over three thousand meteor spectra recorded in Saitama, Japan, between 2018 and 2021 are analysed. We performed a principal component analysis of the intensity of the sodium and magnesium lines and the iron band of each meteor in combination with the orbital elements and the kinematic parameters such as the geocentric velocity and the initial and final altitudes to determine the relative importance of each of these variables in the composition of a meteor’s spectrum. We found that for meteor showers such as GEM, LEO, QUA, and PER, the orbital elements or kinematic parameters are important parameters that determine the intensity of these spectral lines, which could indicate the influence of gravitational and/or non-gravitational forces in distinguishing the composition or variations in the strength of the meteoroid material in each meteor shower. The normal spectral type in our sample ranges from 39.5 per cent to 96.8 per cent, corresponding to GEM and PER, respectively. The COM meteors have a similar sodium content to the components of the LEO and PER showers, suggesting a comet as a possible parent body. The sodium and magnesium content of the iron-class meteoroids is the lowest of all our samples, but it is not zero, suggesting that there are no pure iron meteoroids. The sodium content of the GEM meteor shower shows temporal variations in 2021 compared to the 2019 and 2020 observing seasons. We found no correlation between the sodium content and the perihelion distance for other meteor showers.

The parts of the meteoroid stream originating in comet 109P/Swift-Tuttle crossing the orbits of Mercury, Venus, and Mars

The nucleus of comet 109P/Swift-Tuttle is the source of meteoroids which frequently impact the Earth as the well-known, most powerful meteor shower Perseids, #7. In addition, the stream splits into several other filaments corresponding to few other meteor showers. In this work, we investigated, if the meteoroids of 109P’s stream also impact the other three terrestrial planets. It appeared that there are meteor showers at Venus and Mars, two with the radiants in the northern and one in the southern ecliptic hemisphere of sky. Interestingly, the positions of the radiant areas of 109P’s showers are almost the same at all three planets, Venus, Earth, and Mars. Any shower being so active as the Perseids was predicted neither at Venus nor at Mars, however. Some meteoroids of one filament of the 109P’s stream also impacts the surface of Mercury, but the corresponding shower is predicted so low in number that it can scarcely be detected.

Near-Earth asteroids of cometary origin associated with the Virginid complex

The Virginid meteoroid streams produce a series of meteor showers active annually during February–May. A certain parent comet is not found but a related association of some showers with near-Earth asteroids was previously established and a cometary origin of these asteroids was suggested. We performed a new search for NEAs belonging to the Virginid asteroid–meteoroid complex. On the base of calculation of orbital evolution of a sample of NEAs and determination of theoretical features of related showers a search for observable active showers close to theoretically predicted ones was carried out. As a result, the predicted showers of 27 NEAs were identified with the showers of the Virginid complex. Revealed association points to a cometary nature of NEAs that are moving within the stream and may be considered as extinct fragments of a larger comet-progenitor of the Virginid asteroid–meteoroid complex.

Coupling dynamics of capsule interior defects and its impact on hydrodynamic instabilities at ablation fronts for inertial confinement fusion implosions

The micrometer-scale internal defect in the capsule is one of the most important factors that limit implosion performance in inertial confinement fusion (ICF) experiments, which creates instability seeds as shocks propagate through the capsule shell. Here, we report the generation mechanism of vortex pairs resulting from the interaction of shock waves with multiple bubbles, as well as the origin of more intricate perturbation waves than those observed in the case of single defects. Based on the subsequent evolution of hydrodynamic instability, it is evident that the vortex pairs induce the emergence of low-density (light-bubble case) or high-density (referred to as heavy-bubble case) jets on the ablative front. The presence of multiple side-by-side defects can rapidly amplify the dimensions of the jet. These jets could be responsible for the “meteor shower” observed in implosion experiments. Converging disturbed waves between vertically aligned defects lead to a more complex nonlinear flow field evolution compared to the scenario with a single defect. A systematic study of localized perturbation growth as a function of defect placement is presented. We investigate the dependence of circulation in the flow field on the locations of the defects. The scanning results of defect scenes with different sizes revealed the reason why the depth of fluid penetration is affected by the position and size, and found that the effects of the position and size on the perturbation expansion width can be equivalent to a certain extent. The extension of the perturbation width when the defect is off-axis limits the degree of penetration of the perturbation depth. The results contribute to a more comprehensive understanding of physical processes, such as the seeding mechanism, shell integrity, and mass injection into the central region, which may be applied to inform the development of more effective strategies to mitigate implosion degradation in ICF implosion experiments.