scholarly journals Stability of Asteroid Motions

1992 ◽  
Vol 152 ◽  
pp. 115-122
Author(s):  
Y. Kozai
Keyword(s):  
Dynamical Evolution ◽  
Secular Perturbations ◽  
The Past ◽  
Kirkwood Gaps ◽  
Present Distribution

In this paper the author presents evidences showing that for most of the asteroids the motions are stable in the sense that they never approach major planets very closely and explains about mechanisms to avoid very close approaches by investigating the variations due to the secular perturbations of the eccentricities as functions of the arguments of perihelion, particularly, for asteroids with high eccentricities and inclinations. It is believed that some kinds of dynamical evolution processes have made the asteroid motions stable. The author shows also that there were some kinds of collisions among asteroids in the past which produced families and present distribution of asteroids as there are very faint asteroids only near Kirkwood gaps.

scholarly journals Dynamical evolution of near-Sun objects

2014 ◽  
Vol 9 (S310) ◽  
pp. 126-129
Author(s):  
Vacheslav V. Emel'yanenko ◽  
Mikhail A. Shelyakov
Keyword(s):  
Dynamical Evolution ◽  
Orbital Evolution ◽  
The Other ◽  
Secular Perturbations ◽  
The Past ◽  
Other Hand ◽  
Short Period ◽  
Near Earth Objects

AbstractThe dynamical evolution of short-period objects having perihelia at small heliocentric distances is discussed. We have investigated the motion of multiple-apparition members of the Marsden and Kracht sungrazing groups. The orbital evolution of these objects on timescales < 10 Kyr is mainly determined by the Kozai-Lidov secular perturbations. These objects are dynamically connected with high-inclination near-Earth objects. On the other hand, we have found several observed near-Earth objects that evolve in the same way, reaching small perihelion distances on short timescales in the past.

Colchicum autumnale (Colchicaceae) w okolicach Krakowa – dawne i obecne rozmieszczenie

2019 ◽  
pp. 15-27
Author(s):  
Magdalena Zarzyka-Ryszka
Keyword(s):  
Adjacent Area ◽  
Colchicum Autumnale ◽  
The Past ◽  
The North ◽  
North Eastern ◽  
New Localities ◽  
Present Distribution ◽  
The 19Th Century ◽  
North Eastern Part

The paper describes the past and present distribution of Colchicum autumnale in the vicinity of Cracow, highlights the role of Stanisław Dembosz (who published the first locality of C. autumnale near Igołomia in 1841). Gives information about the occurrence of C. autumnale in Krzeszowice in the 19th century (reported by Bronisław Gustawicz), presents new localities noted in 2012–2014 in meadows in the north-eastern part of the Puszcza Niepołomicka forest and adjacent area (between the Vistula and Raba rivers), and gives a locality found in Cracow in 2005 (no longer extant).

Evidence from the surface configuration of the Moon on its dynamical evolution

1967 ◽  
Vol 296 (1446) ◽  
pp. 298-303
Keyword(s):  
Lunar Surface ◽  
High Velocity ◽  
Dynamical Evolution ◽  
Great Majority ◽  
Major Axis ◽  
The Moon ◽  
Moon System ◽  
The Past ◽  
The Earth ◽  
High Velocity Impacts

Examination of the Moon through large telescopes reveals a multitude of fine detail down to a scale of 1 km or less. The most prominent feature of the lunar surface is the abundance of circular craters. Many investigators agree that a great majority of these craters have been caused by explosions associated with high velocity impacts. It is further generally assumed that the majority of these high velocity impacts took place during the earliest stages of development of the present Earth-Moon system. The morphology of the Moon surface appears in dynamical considerations in the following way. We know from the work of G. H. Darwin that the Moon has been steadily retreating from the Earth. Dynamical considerations suggest that the period of rotation of the Moon on the average equals its period of revolution about the Earth. Thus when the Moon approaches the Earth, its rotation would be accelerated. Since the Moon, like the Earth, approximates to a fluid body, we should expect that a figure of the Moon would have changed in response to its changing rate of rotation. If the craters formed at a time at which the Moon’s figure was markedly different from the present, then initially circular craters would be deformed and any initially circular depression would tend to change into an elliptically shaped depression, with the major axis of the ellipse along the local meridian. Study of the observed distortions of the craters can give evidence as to the past shape of the Moon, provided the craters formed at a time when the Moon possessed a different surface ellipticity. I should like to examine the limitations the present surface structure places on the past dynamical history of the Moon. I will first review briefly calculations bearing on the dynamical evolution of the Earth-Moon system and the implications these calculations have on the past shape of the lunar surface.

DIGITAL ORIGIN OF COSMIC INFLATION

2010 ◽  
Vol 25 (18) ◽  
pp. 1483-1489
Author(s):  
CHUNG-HSIEN CHOU ◽  
HOI-LAI YU
Keyword(s):  
Degrees Of Freedom ◽  
Dynamical Evolution ◽  
Critical Value ◽  
Cosmic Inflation ◽  
The Past ◽  
Physical Universe ◽  
Communication Time ◽  
Hubble Radius ◽  
Time Required ◽  
The Universe

Assuming our physical universe processes and registers information to determine its dynamical evolution, one can put serious constraints on the cosmology that our universe can bear, in particular, the origin of cosmic inflation. The universe evolves to gain her computation capacity which is linear in time t. On the other hand, the growth in content of degrees of freedom (i.e. by integrating in more galaxies) is as t3/2 through expansion. When the in flux of degrees of freedom of the universe grows beyond some value, the computation capacity of the universe becomes insufficient to determine its evolution, the universe fixes its Hubble radius and inflates away its degrees of freedom within its horizon to regain dynamical evolution. The length of inflation is determined by the communication time required by the universe to become aware of the dropping in the degrees of freedom below some critical value by inflation and is proportional to its Hubble radius. We predict that there can be multiple cosmic inflations. The next inflation era will stop after inflating for a period of 1019 sec if the past inflation period of our universe was 10-33 sec.

The Past and Present Distribution of Scheuchzeria Palustris L. in Europe

1965 ◽  
Vol 53 (2) ◽  
pp. 287 ◽  
Author(s):  
J. H. Tallis ◽  
H. J. B. Birks
Keyword(s):  
The Past ◽  
Present Distribution ◽  
Scheuchzeria Palustris

Dynamical evolution of NEAs: Close encounters, secular perturbations and resonances

1996 ◽  
Vol 72 (1-3) ◽  
pp. 151-164 ◽  
Author(s):  
Patrick Michel ◽  
Christiane Froeschl� ◽  
Paolo Farinella
Keyword(s):  
Dynamical Evolution ◽  
Secular Perturbations ◽  
Close Encounters

Past and present distribution and abundance of the black-footed wallaby in the Warburton region of Western Australia

1992 ◽  
Vol 19 (6) ◽  
pp. 605 ◽  
Author(s):  
DJ Pearson
Keyword(s):  
Western Australia ◽  
Aboriginal People ◽  
Rock Outcrops ◽  
Management Intervention ◽  
The Past ◽  
Granite Outcrops ◽  
Close Proximity ◽  
Local Extinctions ◽  
Present Distribution

The black-footed rock-wallaby (Petrogale lateralis) was once widespread and abundant in rock-piles and ranges in the Warburton region of Western Australia. However, by the 1970s a major decline in its distribution and abundance was apparent. Ranges and rock outcrops were searched with local Aboriginal people to document the past and present distribution and abundance of the species and Aboriginal knowledge of its ecology. The journals of explorers, prospectors and surveyors were examined for records of rock-wallabies. Geologists, dingo trappers and other people who had worked in the region since 1930 were interviewed to document more recent sightings. Extant, small populations of rock-wallabies were located in six ranges, where they were inhabiting extensive gabbro rock-piles and rugged quartzite gullies, often in close proximity to permanent water. None of the granite outcrops visited had extant populations. Continuing local extinctions suggest that surviving populations are under threat and management intervention is required for their long term conservation.

An assessment of the past and present distribution status of the whale shark (Rhincodon typus)along the west coast of India

2016 ◽  
Author(s):  
P.V.R. Premjothi ◽  
B.C. Choudury ◽  
Rahul Kaul ◽  
S. Subburaman ◽  
Manoj Matwal ◽  
...  
Keyword(s):  
West Coast ◽  
Whale Shark ◽  
The West ◽  
Rhincodon Typus ◽  
West Coast Of India ◽  
The Past ◽  
Present Distribution

scholarly journals Lobaria pulmonaria (L.) Hoffm. in the southwestern Baltic – Kattegat area

2021 ◽  
Vol 58 ◽  
pp. 183-197
Author(s):  
Ulf Schiefelbein ◽  
Terkel Arnfred ◽  
Christian Dolnik ◽  
Patrick Neumann ◽  
Emilia Ossowska ◽  
...  
Keyword(s):  
Climatic Factors ◽  
Oak Forests ◽  
Air Humidity ◽  
Northern Germany ◽  
Lobaria Pulmonaria ◽  
The Past ◽  
Forestry Practices ◽  
Natural Factors ◽  
Present Distribution ◽  
Northwestern Poland

The past and present distribution of Lobaria pulmonaria in Denmark, northern Germany, northwestern Poland and nemoral parts of Skåne, Blekinge, southwesternmost Småland and southern Öland (Sweden) has been studied. Of 124 localities visited between 2015 and 2018, L. pulmonaria was confirmed at 64 sites, at each of which its habitat ecology and viability were investigated. It is almost extinct in Schleswig-Holstein, in southern Jutland, on the Danish Islands, in southwestern Skåne, in Mecklenburg-Vorpommern and in the western part of Pomerania. It has disappeared almost completely from areas where mesophytic forests form the potential natural vegetation. The commonest habitats for L. pulmonaria are species-poor acidic beech and species-poor oak forests, and the commonest substrates are trunks of beech, followed by oak. L. pulmonaria specimens on about two thirds of the colonized trees were in a healthy condition. The situation is worst in Schleswig-Holstein and on the Danish Islands, but best in Blekinge and central and northern Jutland. Recent distribution seems to be influenced by both anthropogenic (e.g. air pollution by sulphur dioxide and nitrogen and forestry practices) and natural factors (precipitation, temperature, air humidity), as well as unnatural climatic factors (global warming).

scholarly journals When Might 2P/Encke Have Produced Meteor Storms?

1996 ◽  
Vol 150 ◽  
pp. 125-128
Author(s):  
D.I. Steel ◽  
D.J. Asher
Keyword(s):  
Dynamical Evolution ◽  
The Past ◽  
Gravitational Forces ◽  
The Earth ◽  
Short Period Comet ◽  
Short Period ◽  
Meteor Storm ◽  
Pass Through ◽  
Better Than ◽  
Period Comet

Abstract2P/Encke is the only Earth-crossing short-period comet to have a meteoroid/dust trail identified in the data collected by IRAS Such trails have been suggested by Kresák to be the cause of meteor storms, these occurring when the comet/trail node is near 1 AU and the Earth happens to pass through the trail. Here we present the results of integrations of variational orbits of 2P/Encke (the differences in the assumed initial semi-major axes representing the order of changes that could occur due to non-gravitational effects) from which we derive indications of when this comet may have produced meteor storms in the past. Pairs of sets of storms are expected about 300 yr apart, but the effects of chaotic dynamical evolution (and our ignorance of 2P/Encke's non-gravitational forces for any but the last two centuries) mean that we cannot define the epochs in which these may have occurred to better than 200 BC to AD 500 for the last pair, and 3600 to 1800 BC for the previous pair. Looking forwards in time, no meteor storm due to 2P/Encke will occur for at least 600 yr.

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