169 research outputs found
The orbit of the Orgueil meteorite from historical records
Accepted versio
Data on 824 fireballs observed by the digital cameras of the European Fireball Network in 2017-2018. II. Analysis of orbital and physical properties of centimeter-sized meteoroids
Meteoroids impacting the Earth on a daily basis are fragments of asteroids
and comets. By studying fireballs produced during their disintegration in the
atmosphere, we can gain information about their source regions and the
properties of their parent bodies. In this work, data on 824 fireballs
presented in an accompanying paper and catalog are used. We propose a new
empirical parameter for the classification of the physical properties of
meteoroids, based on the maximum dynamic pressure suffered by the meteoroid in
the atmosphere. We then compare the physical and orbital properties of
meteoroids. We find that aphelion distance is a better indicator of asteroidal
origin than the Tisserand parameter. Meteoroids with aphelia lower than 4.9 AU
are mostly asteroidal, with the exception of the Taurids and alpha Capricornids
associated with the comets 2P/Encke and 169P/NEAT, respectively. We found
another population of strong meteoroids of probably asteroidal origin on orbits
with either high eccentricities or high inclinations, and aphelia up to ~ 7 AU.
Among the meteoroid streams, the Geminids and eta Virginids are the strongest,
and Leonids and alpha Capricornids the weakest. We found fine orbital
structures within the Geminid and Perseid streams. Four minor meteoroid streams
from the working list of the International Astronomical Union were confirmed.
No meteoroid with perihelion distance lower than 0.07 AU was detected. Spectra
are available for some of the fireballs, and they enabled us to identify
several iron meteoroids and meteoroids deficient in sodium. Recognition and
frequency of fireballs leading to meteorite falls is also discussed.Comment: accepted in Astronomy and Astrophysic
The desert fireball network: A new camera network in the western Australian Nullarbor
Accepted versio
First light for the desert fireball network
Accepted versio
OT 060420: A Seemingly Optical Transient Recorded by All-Sky Cameras
We report on a ~5th magnitude flash detected for approximately 10 minutes by
two CONCAM all-sky cameras located in Cerro Pachon - Chile and La Palma -
Spain. A third all-sky camera, located in Cerro Paranal - Chile did not detect
the flash, and therefore the authors of this paper suggest that the flash was a
series of cosmic-ray hits, meteors, or satellite glints. Another proposed
hypothesis is that the flash was an astronomical transient with variable
luminosity. In this paper we discuss bright optical transient detection using
fish-eye all-sky monitors, analyze the apparently false-positive optical
transient, and propose possible causes to false optical transient detection in
all-sky cameras.Comment: 7 figures, 3 tables, accepted PAS
Validation of modelling the radiation exposure due to solar particle events at aircraft altitudes
Dose assessment procedures for cosmic radiation exposure of aircraft crew have been introduced in most European countries in accordance with the corresponding European directive and national regulations. However, the radiation exposure due to solar particle events is still a matter of scientific research. Here we describe the European research project CONRAD, WP6, Subgroup-B, about the current status of available solar storm measurements and existing models for dose estimation at flight altitudes during solar particle events leading to ground level enhancement (GLE). Three models for the numerical dose estimation during GLEs are discussed. Some of the models agree with limited experimental data reasonably well. Analysis of GLEs during geomagnetically disturbed conditions is still complex and time consuming. Currently available solar particle event models can disagree with each other by an order of magnitude. Further research and verification by on-board measurements is still neede
Data on 824 fireballs observed by the digital cameras of the European Fireball Network in 2017-2018. I. Description of the network, data reduction procedures, and the catalog
A catalog of 824 fireballs (bright meteors), observed by a dedicated network
of all-sky digital photographic cameras in central Europe in the years
2017-2018 is presented. The status of the European Fireball Network,
established in 1963, is described. The cameras collect digital images of
meteors brighter than an absolute magnitude of about -2 and radiometric light
curves with a high temporal resolution of those brighter than a magnitude ~ -4.
All meteoroids larger than 5 grams, corresponding to sizes of about 2 cm, are
detected regardless of their entry velocity. High-velocity meteoroids are
detected down to masses of about 0.1 gram. The largest observed meteoroid in
the reported period 2017-2018 had a mass of about 100 kg and a size of about 40
cm. The methods of data analysis are explained and all catalog entries are
described in detail. The provided data include the fireball date and time,
atmospheric trajectory and velocity, the radiant in various coordinate systems,
heliocentric orbital elements, maximum brightness, radiated energy, initial and
terminal masses, maximum encountered dynamic pressure, physical classification,
and possible shower membership. Basic information on the fireball spectrum is
available for some bright fireballs (apparent magnitude < -7). A simple
statistical evaluation of the whole sample is provided. The scientific analysis
is presented in an accompanying paper.Comment: accepted in Astronomy and Astrophysic
The problems associated with the monitoring of complex workplace radiation fields at European high-energy accelerators and thermonuclear fusion facilities
The European Commission is funding within its Sixth Framework Programme a three-year project (2005-2007) called CONRAD, COordinated Network for RAdiation Dosimetry. The organisational framework for this project is provided by the European Radiation Dosimetry Group EURADOS. One task within the CONRAD project, Work Package 6 (WP6), was to provide a report outlining research needs and research activities within Europe to develop new and improved methods and techniques for the characterisation of complex radiation fields at workplaces around high-energy accelerators, but also at the next generation of thermonuclear fusion facilities. The paper provides an overview of the report, which will be available as CERN Yellow Repor
Keeping the Vimentin Network under Control: Cell–Matrix Adhesion–associated Plectin 1f Affects Cell Shape and Polarity of Fibroblasts
Mature focal adhesions and fibrillar adhesions act as anchorage sites for vimentin filaments, with plectin isoform 1f being the crucial linker protein. Plectin serves as a nucleation and assembly center for the de novo formation of vimentin networks. Anchored vimentin creates a resilient cage-like core structure that affects cell shape
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