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Autor Thema: Meteor 19.4. ~ 2:13:55 Uhr Ortszeit, westlich von Murmansk, Russland  (Gelesen 3888 mal)

Offline karmaka

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Re: Meteor 19.4. ~ 2:13:55 Uhr Ortszeit, westlich von Murmansk, Russland
« Antwort #15 am: Juli 08, 2014, 14:17:00 nachm. »
Bilder von der Pressekonferenz:

VIDEO-LINK

Die zwei UrFU Wissenschaftler Viktor Grochowski ( Виктор Гроховский ) und Marii Grizewitsch ( Марии Грицевич ) werden nun geehrt, indem zwei Asteroiden nach ihnen benannt werden.

Grochowski wurde ja bereits durch Chelyabinsk bekannt und Marii Grizewitsch war an der Trajektorie-Berechnung des Annama-Meteoroiden beteiligt.

Offline karmaka

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Re: Meteor 19.4. ~ 2:13:55 Uhr Ortszeit, westlich von Murmansk, Russland
« Antwort #16 am: April 08, 2015, 09:35:06 vorm. »
Es gibt eine neue Analyse zum Orbit von Annama

Orbit  and  dynamic  origin  of  the  recently  recovered  Annama’s  H5 chondrite

J.  M.  Trigo-Rodríguez,  et  al.   

Monthly Notices of the Royal Astronomical Society
MNRAS, DOI: 10.1093/mnras/stv378

LINK (Volltext)

Zitat
We describe the fall of Annama meteorite occurred in the remote Kola Peninsula (Russia) close to Finnish border on 2014 April 19 (local time). The fireball was instrumentally observed by the Finnish Fireball Network. From these observations the strewnfield was computed and two first meteorites were found only a few hundred metres from the predicted landing site on 2014 May 29 and 30, so that the meteorite (an H5 chondrite) experienced only minimal terrestrial alteration. The accuracy of the observations allowed a precise geocentric radiant to be obtained, and the heliocentric orbit for the progenitor meteoroid to be calculated. Backward integrations of the orbits of selected near-Earth asteroids and the Annama meteoroid showed that they rapidly diverged so that the Annama meteorites are unlikely related to them. The only exception seems to be the recently discovered 2014UR116 that shows a plausible dynamic relationship. Instead, analysis of the heliocentric orbit of the meteoroid suggests that the delivery of Annama onto an Earth-crossing Apollo-type orbit occurred via the 3:1 mean motion resonance with Jupiter or the nu6 secular resonance, dynamic mechanisms that are responsible for delivering to Earth most meteorites studied so far.

Offline karmaka

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Re: Meteor 19.4. ~ 2:13:55 Uhr Ortszeit, westlich von Murmansk, Russland
« Antwort #17 am: April 25, 2015, 16:51:37 nachm. »
Und nun ist Annama / Аннама auch 'official'

LINK

Zitat
Annama        68.77491°N, 30.78726°E

Murmanskaya oblast’, Russia

Confirmed fall: 2014 Apr 19

Classification: Ordinary chondrite (H5)

History: A bright fireball appeared in the night sky over the Kola Peninsula, close to the Finnish border, on April 19, 2014. It was instrumentally recorded in Finland from the Kuusamo, Mikkeli and Muhos observing sites belonging to the Finnish Fireball Working Group. Additionally, a publicly available <a href="https://www.youtube.com/watch?v=uuwvYdovMEg#ws">video</a> made by Alexandr Nesterov in Snezhnogorsk, Russia, from the opposite side of the fireball track, was carefully calibrated and taken into account in trajectory reconstruction. The fireball was very bright and was witnessed by many eye-witnesses in Russia, Finland, and Norway. The trajectory reconstruction, dark flight simulations and pre-impact orbit determination were done by Esko Lyytinen, Jarmo Moilanen, Steinar Midtskogen, Maria Gritsevich, Valery Lupovka, and Vasily Dmitriev. The initial mass of meteoroid was estimated to be about 500 kg. Based on the analysis of fireball observations it was predicted that part of the meteoroid survived atmospheric entry and reached the ground. Therefore, a meteorite recovery expedition was organized to search the calculated landing area. The international expedition participants were Alexei Ischenko, Tomas Kohout, Nikolai Kruglikov, and Grigory Yakovlev, logistically supported by Maria Gritsevich and Viktor Grokhovsky. The 5-day expedition took place at the end of May following snow melt and preceding vegetation growth. On May 29, 2014, a first 120.4 g meteorite fragment was found by Nikolai Kruglikov on a local forest road within the predicted impact area. A second 47.5 g meteorite fragment was found by Alexei Ischenko nearby on the following day. The name Annama is after a nearby river which is the closest landmark to the find location. Two subsequent expeditions did not lead to recovery of more meteorites.

Physical characteristics: The 120.4 g meteorite is ~70% covered with black fusion crust, with apparent stream lines on one side. The fresh surface is bright with abundant thin dark impact melt veins. The 47.5 g meteorite is fully covered with dark fusion crust. Bulk density of both meteorites (measured with modified Archimedean method using glass beads) is 3.5 g/cm3, grain density of both meteorites (measured with gas pycnometry) is 3.8 g/cm3. Resulting porosity is 5-8% (values measured by T. Kohout and M. Gritsevich, UHelsinki). Bulk density of the second meteorite (measured with Archimedean method using ethanol) is 3.6 g/cm3 (values measured by G. Yakovlev at UrFU). Magnetic susceptibility of both meteorites is log χ = 5.4 (χ in 10-9 m3/kg, measured by T. Kohout and G. Yakovlev).

Petrography: Classification (J. Haloda, P. Halodova, CzGS) Thin sections show a recrystallized fine-grained granular texture. Chondrule shapes are readily delineated. Irregular fractures in olivine and undulatory extinction of olivine and plagioclase indicate a shock stage of S2. Thin veins of impact melt are also present.

Geochemistry: EPMA results (J. Haloda, P. Halodova, CzGS ), Olivine Fa18.6±0.3 (N=60) and low-Ca pyroxene Fs16.6±0.2 and Wo1.26±0.26 (N=65). Also present are diopside (Fs6Wo46), plagioclase (Ab80An14Or6), chromite, chlorapatite, merrillite, troilite, kamacite, taenite and tetrataenite.

Classification (J. Haloda, P. Halodova, CzGS), Ordinary chondrite, H5, S2, W0.

Specimens: 120.4 g main meteorite was divided into a 98.4 g type specimen (UrFU), 6.2 g cut-off (Vernad), 2 thin sections (Vernad and LTKM) and several smaller (below 1 g) fragments (UHelsinki). Second 47.5 g meteorite was divided into 40.0 g and 6.6 g fragments, both located in UHelsinki.

« Letzte Änderung: April 25, 2015, 17:16:17 nachm. von karmaka »

 


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