Shock-induced alterations in the recently found H chondrite Csátalja meteorite and its implications

Shock-driven annealing of pyroxene and shock deformation of olivine were analyzed in a recently found H chondrite called Csátalja. The most characteristic infrared (IR) spectral shape of shock-annealed sub-grained pyroxene was identified: the strongest peak occurs at 860 cm−1 with a smaller shoulder at 837−840 cm−1, and small bands are at 686, 635−638, and 1,044−1,050 cm−1. The appearance of forbidden bands in pyroxene and shift of band positions to a lower wave number in olivines clearly demonstrate the crystal lattice disordering due to shock metamorphism. The shock annealing produced mixed dark melt along fractures, which consists of feldspar−pyroxene and olivine−pyroxene melt. The dark shock melt at sub-grain boundaries of shocked pyroxenes and along fracture of pyroxenes is characterized by elevated Ca, Na, and Al content relative to its environment, detected by element mapping. So far, shock deformation of pyroxene and olivine was not studied by IR spectroscopy; this method has turned out to be a powerful tool in identifying the mixed composition of shock melt minerals. Further study of shock annealing of minerals, together with the context of shock melting at sub-grain boundaries, will provide a better understanding of the formation of high P–T minerals

Nagyhőmérsékletű és vizes átalakulások az NWA10261 CV3 meteorit alapján

Hidroszférák (H2O) szokatlan formában sok apró, primitív égitestben lehettek jelen a fiatal Naprendszerben. E viszonyok megbecslésében a vizes ásványi átalakulások elemzése segít. Az NWA 10261 meteoritot egy marokkói nomád gyűjtő találta, amit Kereszty Zsolt vásárolt meg 2014-ben. A meteorit besorolása az CSFK FGI laboratóriumaiban történt, ami optikai, infravörös spektroszkópiai mérések, és visszaszórt elektronmikroszkópos módszer révén CV3 típusnak bizonyult. A vizsgálatok alapján az NWA 10261 nagy számban tartalmaz amőboid olivin és CAI (kalcium-alumínium-oxid) zárványokat. A nagyhőmérsékletű átalakulás a CAI szemcséken történt, míg a vizes átalakulás a CAI szemcsék peremén és kondrumokban zajlott. A CAI-k peremén a vizes átalakulást a pleonaszt spinell (spinell szemcse vasasodása a peremek mentén), CAI-k és AOA (amőboid olivin) szemcsék peremén fayalit és vastartalmú piroxén jelenléte igazolja. A kondrumok átalakulása során a vas-oxidok lehetnek nem földi eredetűek is, mivel nemcsak a repedések mentén, hanem a kondrum alapanyagában és a kondrumok peremén is gyakoriak, főleg az akkréciós peremek finomszemcsés anyagában jellemzőek. Noha ebben és sok más meteoritban történtek vizes átalakulások, ezek nyomai főleg kis méretskálán jelentkeznek, feltehetőleg ritkán volt globálisan kölcsönható, kiterjedt áramlási rendszer az ilyen ősi objektumokban. Ennek megfelelően a hidroszféra kifejezés csak korlátozottan alkalmazható rájuk, noha sok esetben az égitestek térfogatának jelentős részében fordulhatott elő folyékony H2O

Planetary Transits of the Trans-Atlantic Exoplanet Survey- Candidate TrES-1b

The AAVSO compiled 10,560 CCD observations of the suspected exoplanet transit object TrES-1b covering seven complete transit windows, three windows of partial coverage, and coverage of baseline non-transit periods. Visual inspection of the light curves reveals the presence of slight humps at the egress points of some transits. A boot strap Monte Carlo simulation was applied to the data to confirm that the humps exist to a statistically significant degree. However, it does not rule out systemic effects which will be tested with campaigns in the 2005 observing season

Strewn Field Simulations and Field Searchs of a Few Latest Bolides Over Hungary - Connection with the Fragmentation Height

nspired by several unsuccessful field searches on the probable fall locations, we reanal-ised a few most recently observed blowing bolides ap-peared over Hungary on: 18:47:33 UTC 8 April, 2018; 17:31:01 UTC April 06, 2015 (so-called "Easter Bo-lide"); and 19:02:08 UTC August 24, 2013. This study is based on careful recalibration of all available obser-vational materials, and both the visual orbit calculation and dark flight integration were done with codes de-veloped by us. For atmospheric model we used the International Standard Atmosphere (ISA1975), while the concrete meteorological parameters of the given dates were taken from ECMWF tables. We simulated the 'theoretical' strewnfields, showed some example on the logged real field searches and gave some com-ments. Finally we present a simple comparison of the structure and sizes of the calculated strewn fields to the well-studied historical strewnfields. Some conse-quences are deduced for the present and next field searches. A typical freefall starts about 25 km height or even higher, where the final desintegrations happen usually. Under this initial parameter the fragments are thrown along a longer strip, which makes the field searches to exhibit very low effectivity. Only some lucky circumstances (like the fortunate geometry of meteor path), better quality professional camera input data and additional technics (radar or accurate seismic detection) can help to find new fell meteorites

Formation and shock impact history of the Csatalja ordinary chondrite

The analysis of the Csatalja H4 chondrite (which was found in August 2012) suggests shock-related textures and spatial inhomogeneities, indicating a complex geological history. In the most heavily fractured and sheared units, small opaque grains and older fractures have locally enhanced the shock effect, producing melt. While the impact textures were evident in most units of the meteorite, mechanical shearing is apparent in only two units, suggesting that these units might have been present at somewhat different locations inside the parent body. Shearing also occurred at the border of the so-called xenolith unit, confirming its mechanical mixing with the other units. Besides fragmentation and melting, chemical changes due to impact have also been identified, producing compositional homogenization of olivines in 30% of the investigated area of the sample’s thin section (23 mm2), and moderate accumulation of Fe, Ca, and Na in the strongly shocked zones, initiating crystallization of feldspar in veins with a specific spatial distribution (feldspar glass with metal–sulfide globules). Analyzing the high P–T minerals, the peak shock pressure and temperature values differed substantially in the various units, ranging between 2 and 17 GPa, 100 and >1200 °C