Data on 824 fireballs observed by the digital cameras of the European Fireball Network in 2017–2018

Borovička, J.; Spurný, Pavel; Shrbený, L.

doi:10.1051/0004-6361/202244197

Cited by 11 publications

(8 citation statements)

References 71 publications

(89 reference statements)

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“…The trend in PE values depending on the mass of meteoroids is also very clear, that is, more massive meteoroids are more fragile. The PE criterion for 3 Draconid and other fireballs observed in 2017-2018 (Borovička et al 2022a) shows that the τ Herculids we observed are the most fragile meteoroids observed ever. Their PE is usually lower than Hurbanovo (all-sky+IP), Kunžak (all-sky+IP), Rimavská Sobota (all-sky), Martinsberg (all-sky), Veselí nad Moravou (IP), Ondřejov (IP) that of other meteors and even than that of Draconid meteors of the same mass.…”

Section: En310522_013924: the Exceptional Case Of A Bright τ Herculid...mentioning

confidence: 55%

τ Herculid meteor shower in the night of 30/31 May 2022 and the meteoroid properties

Koten

Shrbený

Spurný

et al. 2023

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Context. A τ Herculid meteor outburst or even storm was predicted to occur by several models around 5 UT on 31 May 2022 as a consequence of the break-up of comet 73P/Schwassmann-Wachmann 3 in 1995. The multi-instrument and multi-station experiment was carried out within the Czech Republic to cover possible earlier activity of the shower between 21 and 1 UT on 30/31 May. Aims. We report meteor shower activity that occurred before the main peak and provide a comparison with the dynamical simulations of the stream evolution. The physical properties of the meteoroids are also studied. Methods. Multi-station observations using video and photographic cameras were used to calculate the atmospheric trajectories and heliocentric orbits of the meteors. Their arrival times were used to determine the shower activity profile. The physical properties of the meteoroids were evaluated using various criteria based on meteor heights. The evolution of the spectra of three meteors were studied as well. Results. This annual but poor meteor shower was active for the whole night many hours before the predicted peak. A comparison with dynamical models shows that a mix of older material ejected after 1900 and fresh particles originating from the 1995 comet fragmentation event was observed. The radiant positions of both groups of meteors were identified and were found to agree well with the simulated radiants. Meteoroids with masses between 10 mg and 10 kg were recorded. The mass distribution index was slightly higher than 2. The study of the physical properties shows that the τ Herculid meteoroids belong to the most fragile particles observed ever, especially among higher masses of meteoroids. The exceptionally bright bolide observed during the dawn represents a challenge for the dynamical simulations as it is necessary to explain how a half-metre body was transferred to the vicinity of the Earth at the same time as millimetre-sized particles.

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Section: En310522_013924: the Exceptional Case Of A Bright τ Herculid...mentioning

confidence: 55%

τ Herculid meteor shower in the night of 30/31 May 2022 and the meteoroid properties

Koten

Shrbený

Spurný

et al. 2023

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“…The distribution of aerodynamic pressure that fragments asteroidal fireballs varies more than in Geminids because the fireballs are a random sample of sporadic background. Additionally, the fireballs used for the modeling were chosen to be similar to Geminids in terms of entry masses and some also in velocities, masses and velocities that are less typical for asteroidal orbits (Borovička et al 2022a). Therefore, we could have expected the modeled meteoroids would come from various sources and would have different mechanical properties as well.…”

Section: Discussionmentioning

confidence: 99%

“…The unclear formation scenario and the actual nature of Phaethon and the Geminids is the main motivation for the present study. Another motivation is the notion that small Geminids tend to be weaker than large ones (Borovička et al 2022a). Therefore, we address the question of the physical and mechanical properties of the Geminid meteoroid material by modeling their fragmentation cascade in the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Mechanical strength distribution in Geminid meteoroids derived via fireball modeling

Henych,

Borovička,

Vojáček

et al. 2024

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Geminids are the most active annual meteor shower observed on Earth. Their parent is an active asteroid, (3200) Phaethon, which is a target of the planned $ DESTINY ^+$ mission of the Japan Aerospace Exploration Agency (JAXA). The exact physical nature of (3200) Phaethon and Geminids is still debated. This paper is devoted to fragmentation modeling of bright Geminid fireballs, which should reveal information about the structure of centimeter-sized Geminid meteoroids. These fireballs were observed by the European Fireball Network (EN) over the past few years. We aim to describe their disintegration cascade in the atmosphere and their mechanical properties, and to derive their precise initial masses and velocities. We used a semi-empirical fragmentation model that employs an automatic procedure based on parallel genetic algorithms to determine the aerodynamic pressures at which a meteoroid and its parts fragment. This serves as a proxy for the mechanical strength of the body and its subsequent fragments. It enabled us to derive the minimum, median, and maximum mechanical strength and the strength distribution inside the meteoroid and reveal its internal structure. We find that the Geminids begin to crumble at pressures $1 kPa $ with the strongest parts reaching pressures of between $0.4$ and $1.55\ MPa $ before fragmenting. Knowing the spectral type of (3200) Phaethon (a B-type asteroid, part of the C complex), we conclude that the Geminids are made of compact and coherent carbonaceous material. We also find that the minimum aerodynamic pressure that causes the fragmentation of Geminids increases with increasing entry mass of Geminids. In contrast, the median aerodynamic pressure decreases as their entry mass increases. The spectra of all the observed Geminid fireballs show normal content and little variation in terms of sodium.

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“…However, it may not be convincing enough in the case of 2022 EB5, since the terminal height where the bright trajectory ends remains unknown and the calculation of terminal height can be very dependent on the fragmentation model chosen. A newly defined parameter, called the pressure resistance factor or pressure factor (PF) was proposed by Borovicka et al (2022) to evaluate the structural strength on the basis of the maximal ram pressure. We chose the PF parameter to constrain the material strength of the object as the maximum ram pressure is more robust, easier to obtain and less dependent on observing circumstances than the terminal height.…”

Section: Physical Properties Of 2022 Eb5mentioning

confidence: 99%

Near-Earth object 2022 EB5: From atmospheric entry to physical properties and orbit

Geng

Zhou

2023

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Context. The near-Earth object (NEO) 2022 EB5 is the fifth NEO found prior to entering the Earth's atmosphere. It fragmented over the Norway Sea on 2022 March 11 about two hours after being discovered by the astronomer Krisztián Sárneczky at Konkoly Observatory in Hungary. The Center for Near-Earth Object Studies (CNEOS) at NASA detected the visible radiation emitted at the time of its atmospheric entry. The Jet Propulsion Laboratory (JPL) and European Space Agency (ESA) derived its orbital elements based on observations of its pre-atmospheric orbit. Aims. This paper aims to calculate the physical properties of this NEO, in particular, the bulk strength, type of the material, albedo, size, and mass, based on observations of its peak brightness at the time of its atmospheric entry. In addition, the heliocentric elements are computed from its interaction with Earth's atmosphere and compared with those derived from observations by JPL and ESA, respectively, to evaluate the accuracy of our method. Methods. The flight equations of 2022 EB5 were inversely integrated from the peak brightness to the atmospheric boundary via the fourth-order Runge-Kutta method. A pancake model was utilized to simulate the fragmentation of the impactor. Parameters needed to complete the integration process that were unknown were set to be optimization variables and determined via a genetic algorithm. Results. The results obtained show that 2022 EB5 was most likely a C-type asteroid with a maximal bulk strength of 2 MPa, diameter of 5–6 m, cometary density, and very low albedo that is no greater than 0.025. In addition, considering the effects of the atmosphere is helpful in getting a more accurate measurement for the semi-major axis, eccentricity, and inclination, although the accuracy of orbital elements strongly depends on the accuracy of USG sensors.

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Data on 824 fireballs observed by the digital cameras of the European Fireball Network in 2017–2018

Cited by 11 publications

References 71 publications

τ Herculid meteor shower in the night of 30/31 May 2022 and the meteoroid properties

τ Herculid meteor shower in the night of 30/31 May 2022 and the meteoroid properties

Mechanical strength distribution in Geminid meteoroids derived via fireball modeling

Near-Earth object 2022 EB5: From atmospheric entry to physical properties and orbit

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