Search results for "asteroid"
showing 10 items of 53 documents
Distribution and diet of Marthasterias glacialis at Ustica Island MPA
2009
Distribution and diet of Marthasterias glacialis was studied at Ustica Island MPA. We conducted observations of the asteroid along the upper infralittoral zone using random parallel transects. M. glacialis was more abundant at study sites characterized by low densities of erect algae. Most frequent prey species was a bivalve and sea urchins
Looking for the origin of life in cosmochemistry : asteroids and their carbon-rich meteorites
2015
Carbonaceous chondrite meteorites are carbon-containing fragments of primitive asteroids that have offered the only samples available to date giving insights into chemical evolution in laboratory analyses. Their study has revealed that abundant organic chemistry came to be in the Solar System ahead of terrestrial life and, by the input of these meteorites and comets, might have aided in the origin of our planet’s biochemistry.
Small solar system bodies as granular systems
2017
Asteroids and other Small Solar System Bodies (SSSBs) are currently of great scientific and even industrial interest. Asteroids exist as the permanent record of the formation of the Solar System and therefore hold many clues to its understanding as a whole, as well as insights into the formation of planetary bodies. Additionally, SSSBs are being investigated in the context of impact risks for the Earth, space situational awareness and their possible industrial exploitation (asteroid mining). In all these aspects, the knowledge of the geophysical characteristics of SSSB surface and internal structure are of great importance. Given their size, constitution, and the evidence that many SSSBs ar…
What a New Model of Skeletal Homologies Tells Us About Asteroid Evolution1
2000
The Extraxial-Axial Theory (EAT) is applied to the body wall homologies of asteroids. Attempts to characterize major plate systems of asteroids as axial or extraxial, particularly those that are highly organized into series, can be problematic. However, the Optical Plate Rule (OPR) is instrumental in establishing that ambulacrals and terminals are axial. It is equally clear that the region aboral to the marginal frame is a part of the perforate extraxial body wall (with the possible exception of the centrodorsal, which is likely imperforate extraxial). Previously established EAT criteria, particularly those strongly rooted in the embryologically expressed boundary between axial and extraxia…
Description of two new fossil echinoids (Echinodermata: Echinoidea) from the Early Hauterivian (Early Cretaceous) of the Paris Basin (France)
2012
International audience; Deux nouveaux genres et espèces d'échinides, Salvaster roberti gen. et sp. nov. et Pygolampas edita gen. et sp. nov. provenant de la Formation des Calcaires à Spatangues (CSF) sont décrits. La CSF correspond à des sédiments calcaréo-argileux déposés dans le sud-est du bassin de Paris (France) à l'Hauterivien inférieur (Crétacé inférieur). Ces dépôts sont datés de la chronozone à Acanthodiscus radiatus, un intervalle de temps qui a correspondu à un haut niveau marin général en Europe de l'Ouest. La CSF a pourtant livré une riche faune fossile d'environnement marin peu profond, principalement représentée par des invertébrés benthiques. Parmi ceux-ci, 54 espèces d'échin…
Análisis espectroscópico de fragmentos cometarios y asteroidales a su entrada en la atmósfera terrestre.
2002
En la presente tesis se analiza el origen y composición de la materia interplanetaria a partir de una perspectiva nueva basada en el estudio de los fenómenos luminosos que producen estas partículas a su entrada a la atmósfera terrestre, llamados meteoros. Estas partículas, procedentes mayoritariamente de la degradación de las superficies de cometas y asteroides, cuando se hayan en órbita solar se denominan genéricamente meteoroides. Dependiendo de la geometría del encuentro con la Tierra los meteoroides alcanzan la atmósfera a velocidades comprendidas en el rango de 11 a 73 km/s. A estas velocidades a alturas de entre 120 y 70 km. la densidad atmosférica es suficiente para que las colisione…
Dust environment of an airless object: A phase space study with kinetic models
2016
Abstract The study of dust above the lunar surface is important for both science and technology. Dust particles are electrically charged due to impact of the solar radiation and the solar wind plasma and, therefore, they affect the plasma above the lunar surface. Dust is also a health hazard for crewed missions because micron and sub-micron sized dust particles can be toxic and harmful to the human body. Dust also causes malfunctions in mechanical devices and is therefore a risk for spacecraft and instruments on the lunar surface. Properties of dust particles above the lunar surface are not fully known. However, it can be stated that their large surface area to volume ratio due to their irr…
Astrometry and photometry of digitized plates of Baldone Schmidt telescope
2021
Abstract During the 40-year photographic period of astronomical observations, the Baldone Astrophysical Observatory has accumulated more than 22,000 direct and 2,500 spectral images. In 2018, the digitization of direct astrophoto images with a resolution of 1200 dpi was completed. A processing methodology for obtaining the equatorial coordinates and photometric characteristics of the objects recorded in digitized astronegatives using the LINUX/MIDAS/ROMAFOT environment has been developed at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine. Program package with success already works in seven observatories. A description of the operation of this program complex…
Astronomy and space on the big screen : how accurately has cinema portrayed space travel and other astrophysical concepts?
2016
"Since its origins, cinema has been fascinated with the subject of scientific developments. In particular, astronomy and astrophysics have played an important role in science fiction stories about space travel and exploration. Though the science has not always been accurately represented, in the last decades there has been more and more interest from the cinema industry in approaching scientists to make sure that the stories and concepts shown in films are closer to our true understanding of the universe. In this article, I will explore how cinema has portrayed astrophysical concepts throughout the decades, and how sometimes cinema has even inspired the direction of scientific research."
INVESTIGATION OF NEO ASTEROIDS 2006 VB14 AND 1986 DA
2019
566 positions and photometric observa- tions of NEO objects 2006 VB14 = Y5705 = 345705 and 1986 DA were obtained with Baldone Schmidt telescope in 2018 and 2019, to detecting rotation period and other physical characteristics. A Fourier transform was applied to determine the rotation period for asteroid 1986 DA=6178. Value 3.12 ± 0.02h was obtained. Observations confirm the previously obtained rotation period P = 3.25h for 2006 VB14.