scholarly journals Is the near-Earth asteroid 2000 PG3 an extinct comet?

2006 ◽  
Vol 2 (S236) ◽  
pp. 135-140
Author(s):  
Pulat B. Babadzhanov ◽  
Iwan P. Williams
Keyword(s):  
Cometary Nucleus ◽  
Meteor Shower ◽  
Published Data ◽  
The Sun ◽  
Meteor Showers ◽  
Orbital Elements ◽  
Night Time ◽  
Gravitational Action ◽  
Earth Asteroid ◽  
Secular Variations

AbstractThe existence of an observed meteor shower associated with some Near-Earth Asteroid (NEA) is one of the few useful criteria that can be used to indicate that such an object could be a candidate for being regarded as an extinct or dormant cometary nucleus. In order to identify possible new NEA-meteor showers associations, the secular variations of the orbital elements of the NEA 2000 PG3, with comet-like albedo (0.02), and moving on a comet-like orbit, was investigated under the gravitational action of the Sun and six planets (Mercury to Saturn) over one cycle of variation of the argument of perihelion. The theoretical geocentric radiants and velocities of four possible meteor showers associated with this object are determined. Using published data, the theoretically predicted showers were identified with the night-time September Northern and Southern δ-Piscids fireball showers and several fireballs, and with the day-time meteor associations γ-Arietids and α-Piscids. The character of the orbit and low albedo of 2000 PG3, and the existence of observed meteor showers associated with 2000 PG3 provide evidence supporting the conjecture that this object may be of cometary nature.

scholarly journals Investigation of the Motion of Periodic Comet Giacobini-Zinner and the Origin of the Draconid Meteor Showers of 1926, 1933 and 1946

1972 ◽  
Vol 45 ◽  
pp. 173-180
Author(s):  
Yu. V. Evdokimov
Keyword(s):  
Meteor Shower ◽  
Meteor Showers ◽  
Orbital Elements ◽  
Periodic Comet

Orbital elements of P/Giacobini-Zinner have been obtained from 577 observations at the eight apparitions 1900 to 1965 by linking apparitions in pairs. By this technique we established that the comet has a nongravitational secular deceleration amounting, on the average, to 0.081 day/(period)2. As a result of the comet's approach to Jupiter in 1969, a return of the Draconid meteor shower is possible on 1972 October 8d15h45m UT. The 1946 meteor shower was due to meteoroids ejected forward along the orbit of the comet in 1940 with velocities of 14 m s- 1. The meteor showers of 1933 and 1926 were apparently produced by meteoroids ejected in 1900 with velocities of 15.0 m s- 1 forward and 14.5 m s- 1 backward, respectively.

Meteor Showers: which ones are real and where do they come from?

2012 ◽  
Vol 10 (H16) ◽  
pp. 142-142
Author(s):  
Peter Jenniskens
Keyword(s):  
Solar System ◽  
Ground Truth ◽  
Meteor Shower ◽  
General Assembly ◽  
Meteor Showers ◽  
Orbital Elements ◽  
Meteoroid Streams ◽  
Zodiacal Cloud ◽  
History Of ◽  
To Receive

AbstractThe IAU Meteor Shower Working List contains 369 showers, of which only 64 are considered established (per February 28, 2012). In this invited review, we will give an overview of international efforts to validate the remaining showers. We report on the showers that were validated in this triennium and proposed to receive the predicate “established" at the present General Assembly. The meteoroid orbit surveys characterize the meteoroid streams in terms of orbital elements and their dispersions, which is ground truth for efforts to identify their parent comets, study the fragmentation history of the (mostly dormant) comet population in the inner solar system, and understand the origin of the zodiacal cloud.

Models of comets with strongly variable nongravitational effects

1999 ◽  
Vol 173 ◽  
pp. 381-387
Author(s):  
M. Królikowska ◽  
G. Sitarski ◽  
S. Szutowicz
Keyword(s):  
Cometary Nucleus ◽  
Spin Axis ◽  
Reactive Force ◽  
Orbital Elements ◽  
Cometary Nuclei ◽  
Short Period ◽  
Basic Parameters ◽  
Polar Radius ◽  
Cometary Activity ◽  
Nongravitational Effects

AbstractThe nongravitational motion of five “erratic” short-period comets is studied on the basis of published astrometric observations. We present the precession models which successfully link all the observed apparitions of the comets: 21P/Giacobini-Zinner, 31P/Schwassmann-Wachmann 2, 32P/Comas Solá, 37P/Forbes, and 43P/Wolf-Harrington. We used the Sekanina's forced precession model of the rotating cometary nucleus to include the nongravitational terms into equations of the comet's motion. Values of six basic parameters (four connected with the rotating comet nucleus and two describing the precession of spin-axis of the nucleus) have been determined along the orbital elements from positional observations of the comets. The solutions were derived with additional assumptions which introduce instantaneous changes of modulus of reactive force,Aand of maximum of cometary activity with respect to perihelion time. The present precession models impose some contraints on sizes and rotational periods of cometary nuclei. According to our solutions the nucleus of 21P/Giacobini-Zinner with oblateness along the spin-axis of about 0.32 (equatorial to polar radius of 1.46) is the most oblate among five investigated comets.

scholarly journals A Lesson of Sustainability Given by The Tropical Modernism in Kinshasa: The BCB Headquarters by Maurice Houyoux

2021 ◽  
Vol 3 (1) ◽  
pp. p22
Author(s):  
Alexis Tshiunza ◽  
Manlio Michieletto ◽  
Olatunde Adedayo
Keyword(s):  
Building Materials ◽  
Relevant Literature ◽  
Weather Condition ◽  
Tropical Region ◽  
Published Data ◽  
The Sun ◽  
Existing Buildings ◽  
Key Issues ◽  
Observation Method ◽  
Belgian Congo

The tropical region is often considered as a region where the sun shines intensely and the temperature varies at certain times of the year. In the case of Congo, the average weather condition is considered cool, however, there have been cases where the temperature reached up to 43° C. It is therefore imperative for buildings in this region to take into account the temperature variation while considering the comfort of the users. During the design and construction of the Bank of Belgian Congo, the availability of data to assist the architect Maurice Houyoux in meeting the challenge of the region was unavailable. The architect had to be creative in planning and overcoming the challenges posed by the environment. This paper seeks to examine the issues confronted by Maurice Houyoux and the design solutions he provided to ensure that the building was functional and responded to the tropical challenges. In undertaking this study, a historical approach was adopted through the review of relevant literature on the building and designs within the period of the development of the bank. An observation method was also deployed to verify some of the information found in the literature. The findings are presented using pictures and sketches to explain some of the key issues relevant to the design of the bank. The findings showed that despite the reduced number of published data for designing in such a region, the architect was able to examine the existing buildings and discuss with users of other constructions to obtain relevant data. The findings also showed that the building was able to respond to peculiar requirements to be functional. The paper concludes that the local building materials and traditional builders can be used to achieve a contemporary building that fits into the context towards sustainable architecture.

scholarly journals Spatial Exclusion, Due Process, and the Civilianization of Punishment in Australia’s Night-time Economy: A Mapping Review of Patron Banning Policy, Practice, and Oversight

2020 ◽  
pp. 105756772093915
Author(s):  
Clare Farmer ◽  
Robyn Clifford
Keyword(s):  
Policy Development ◽  
Due Process ◽  
Research Literature ◽  
Deterrent Effect ◽  
Published Data ◽  
Night Time ◽  
Empirical Examination ◽  
Wide Range ◽  
Mapping Review ◽  
Spatial Exclusion

Jurisdictions across Australia have implemented a range of policies to tackle problems associated with alcohol consumption in and around licensed premises. One key measure, patron banning, has proliferated in various forms. Banning applies spatial restrictions and locational prohibitions upon recipients. It is typically predicated upon a presumed deterrent effect for both recipients and the wider community to reduce alcohol-related disorderly behaviors and to improve public safety. This article documents a mapping review of patron banning mechanisms across Australian jurisdictions, using an analysis of legislation, operational practices, policy documentation and reviews, published data, and research literature. The mapping review then frames an analysis of banning policy. Key conceptual and operational issues are discussed with respect to deterrence and community protection; displacement, diffusion, and isolation of effects; enforcement; due process and legitimacy; and the steady civilianization of punishment. Given the wide range and reach of banning mechanisms, there is an urgent need for specific empirical examination of the use and effect of spatial exclusion and prohibition across Australia’s nighttime economy to inform policy development and refinement, to strengthen the assurance of due process, and to optimize the potential beneficial effects of patron banning.

scholarly journals Ultraviolet photometry of stars obtained with the Celescope experiment in the Orbiting Astronomical Observatory

1970 ◽  
Vol 36 ◽  
pp. 109-119
Author(s):  
Robert J. Davis
Keyword(s):  
Astronomical Observatory ◽  
Published Data ◽  
The Sun ◽  
The Moon ◽  
Wavelength Band ◽  
Giant Stars ◽  
Outer Atmosphere ◽  
Consistent Picture ◽  
Far Ultraviolet ◽  
Star Fields

We have used the television photometers in the Celescope OAO experiment to measure the far ultraviolet brightnesses of several thousand stars, including parts of the constellations Draco, Lyra, Puppis, Vela, Taurus, and Orion; and the Moon. As of this date (22 July 1969), three of our four cameras continue to operate satisfactorily, and we are making measurements in additional star fields distributed throughout the sky. Our shortest wavelength band, which includes the Lyman α line of atomic hydrogen, provides information on the Earth's outer atmosphere, as well as on star brightnesses. The intensity of the Lyman α radiation from the geocorona is a maximum when the Sun is near the horizon as seen by the OAO, and a minimum when the Sun is in the nadir. The direction that the telescope points does not much affect the measured intensities.Because of the heavy logistic problems of identification, calibration, and measurement for so many stars and because of the survey character of the program, the scientific interpretation of the results is, as expected, lagging the measurement program. However, one consistent picture beginning to emerge from our data is that our observed stars are about equally divided between those that fall within 0.5 magnitude of the predicted ultraviolet brightnesses and those that are significantly fainter than predicted. Most of the giant stars we observe exhibit these ultraviolet deficiencies. Since some of these giants are stars for which little or no interstellar reddening is predicted, we attribute the observed deficiencies to the stars themselves.Many of the objects we observe do not have accurate ground-based published data regarding magnitude, color, and spectral type; new ground-based observations of these objects are required to ensure satisfactory interpretation of our results.

scholarly journals Rotation Effects in the Nongravitational Parameters of Comets

1972 ◽  
Vol 45 ◽  
pp. 294-300 ◽  
Author(s):  
Z. Sekanina
Keyword(s):  
Cometary Nucleus ◽  
Secular Variations ◽  
Precessional Motion ◽  
Effects Of Rotation

The effects of rotation of a cometary nucleus on the character of nongravitational parameters are discussed. It is suggested that the change of a nongravitational acceleration to deceleration (and vice versa) may be related to a precessional motion of the nucleus, or to secular variations in the lag angle coupled with severe orbital modifications.

scholarly journals Variations in Solar Radiation and the Cause of Ice Ages

1950 ◽  
Vol 1 (08) ◽  
pp. 453-455 ◽  
Author(s):  
F. Hoyle ◽  
R. A. Lyttleton
Keyword(s):  
Solar Radiation ◽  
Stellar Evolution ◽  
Recent Progress ◽  
Solar Surface ◽  
The Sun ◽  
Total Radiation ◽  
Ice Ages ◽  
Gravitational Action ◽  
Extra Energy ◽  
Possible Cause

Abstract Most astronomical hypotheses on the causes of ice ages are dynamically untenable. Alterations in the amount of solar radiation, however, have long been recognized as a possible cause, but only with recent progress in the theory of stellar evolution has it become clear that such changes must occur. At irregular intervals the sun will pass, and will have passed, with low relative speeds through interstellar hydrogen clouds, and the gravitational action of the sun leads to an increase in the quantity of material falling to the surface with high velocity. The conversion of the kinetic energy of fall of this material results in an increase of emission at the solar surface. Increases of order up to about 10 per cent of the present total radiation could occur, and the process is such that the extra energy would be located mainly in the shorter wavelengths.

scholarly journals The orbital evolution of meteor streams at the 2/1 resonance with Jupiter

1985 ◽  
Vol 83 ◽  
pp. 179-180
Author(s):  
Cl. Froeschlé
Keyword(s):  
Major Axis ◽  
Orbital Evolution ◽  
The Sun ◽  
Orbital Elements ◽  
Meteor Stream ◽  
Semi Major Axis ◽  
Meteor Streams ◽  
Gravitational Forces ◽  
Resonant Effect

We investigated the orbital evolution of Quadrantid-like meteor streams situated in the vicinity of the 2/1 resonance with Jupiter. For the starting orbital elements we took the values of the orbital elements of the Quadrantid meteor stream except for the semi-major axis which was varied between a = 3.22 and a = 3.34 AU. We considered these meteor streams as a ring and we investigated the resonant effect on the dispersion of this ring over a period of 13 000 years. Only gravitational forces due to the Sun and due to Jupiter were taken into account.

scholarly journals On the Causes of Palaeoclimatic Variations and of the Ice Ages in Particular

1953 ◽  
Vol 2 (13) ◽  
pp. 213-218
Author(s):  
E. J. Öpik
Keyword(s):  
Nuclear Reactions ◽  
Gas Diffusion ◽  
Seasonal Temperature ◽  
The Sun ◽  
Orbital Elements ◽  
Ice Ages ◽  
Solar Mass ◽  
The Earth ◽  
Change In The Mean ◽  
The Mean

AbstractA method of quantitative climatological analysis is developed by applying the principle of geometric similarity to the convective heat transport, which is assumed to vary with the 1.5 power of temperature difference. The method makes possible the calculation of the change in the mean annual, or seasonal temperature, produced by a variation in insolation, cloudiness, snow cover, etc.It is shown that the variations in the orbital elements of the earth cannot account for the phenomena of the ice ages; the chronology of the Quaternary, based on these variations, has no real foundation.Palaeoclimatic variations are most probably due to variations of solar luminosity. These can be traced to periodical re-adjustments in the interior of the sun, produced by an interplay between nuclear reactions and gas diffusion, repeating themselves after some 250 million years. Complications from the outer envelope of the sun lead to additional fluctuations of a shorter period, of the order of 100,000 years to be identified with the periodical advance and retreat of the glaciers during the Quaternary.Calculations of the variations of luminosity in a star of solar mass substantiate this hypothesis.

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