scholarly journals Kharkiv study of near-Earth asteroids

2006 ◽  
Vol 2 (S236) ◽  
pp. 385-390 ◽  
Author(s):  
Yu. N. Krugly ◽  
N. M. Gaftonyuk ◽  
I. N. Belskaya ◽  
V. G. Chiorny ◽  
V. G. Shevchenko ◽  
...  
Keyword(s):  
Surface Properties ◽  
Crimean Astrophysical Observatory ◽  
Photometric System ◽  
Rotation Periods ◽  
Photometric Observations ◽  
National University ◽  
Ccd Observations ◽  
Asteroid Hazard ◽  
Near Earth Asteroids

AbstractThe regular CCD observations of near-Earth asteroids (NEAs) in the Institute of Astronomy of Kharkiv National University were initiated in 1995 within the framework of asteroid hazard problem in collaboration with the DLR, Institute of Planetary Research (Berlin). The main aim of the study is a determination of rotation periods and shapes of NEAs as well as astrometry of newly discovered objects. We also carry out the absolute photometry of NEAs in BVRI bands in order to put constraints on surface properties and to estimate their diameters. The observations are carried out with 0.7-m telescope of the Institute of Astronomy (Kharkiv) and with 1-m telescope of the Crimean Astrophysical Observatory (Simeiz) in the standard Johnson-Cousins photometric system. Some observations were made as an optical support of radar observation of NEAs. We present the results of photometric observations of 21 NEAs obtained in 2004-2006 which include asteroid rotation properties, diameters and shapes.

Combined determination of surface properties of nano-colloidal particles through ion selective electrodes with potentiometer

The Analyst ◽  
2013 ◽  
Vol 138 (4) ◽  
pp. 1122-1129 ◽  
Author(s):  
Xinmin Liu ◽  
Hang Li ◽  
Rui Li ◽  
Rui Tian ◽  
Chenyang Xu
Keyword(s):  
Surface Properties ◽  
Colloidal Particles ◽  
Ion Selective Electrodes

scholarly journals NEA rotations and binaries

2006 ◽  
Vol 2 (S236) ◽  
pp. 167-176 ◽  
Author(s):  
Petr Pravec ◽  
A. W. Harris ◽  
B. D. Warner
Keyword(s):  
Binary Systems ◽  
Principal Axis ◽  
Spin Distribution ◽  
Rotation Periods ◽  
System A ◽  
Binary Formation ◽  
Basic Spin ◽  
Axis Rotation ◽  
Near Earth Asteroids ◽  
Abundant Population

AbstractOf the nearly 3900 near-Earth asteroids (NEAs) known as of June 2006, 325 have estimated rotation periods, with most of those determined by lightcurve analysis led by a few dedicated programs. NEAs with diameters down to 10 meters have been sampled. Observed spin distribution shows a major changing point around diameter of 200 meters. Larger NEAs show a barrier against spins faster than 11 d−1 (period about 2.2 h) that shifts to slower rates (longer periods) with increasing lightcurve amplitude (i.e., with increasing equatorial elongation). The spin barrier is interpreted as a critical spin rate for bodies in a gravity regime; NEAs larger than 200 meters are predominantly bodies with tensile strength too low to withstand a centrifugal acceleration for rotation faster than the critical spin rate. The cohesionless spin barrier disappears at sizes less than 200 meters where most objects rotate too fast to be held together by self-gravitation only, so a cohesion is implied in the smaller NEAs.The distribution of NEA spin rates in the cohesionless size range (D0.2 km) is highly non-Maxwellian, suggesting that mechanisms other than just collisions have been at work. There is a pile up just in front of the barrier, at periods 2–3 h. It may be related to a spin up mechanism crowding asteroids to the barrier. An excess of slow rotators is observed at periods longer than 30 hours. A spin-down mechanism has no obvious lower limit on spin rate; periods as long as tens of days have been observed.Most NEAs appear to be in their basic spin states with rotation around principal axis with maximum moment of inertia. Tumbling objects (i.e., bodies in excited, non-principal axis rotation) are present and actually predominate among slow rotators with estimated damping timescales longer than the age of the solar system. A few tumblers observed among fast rotating coherent objects appear to be either more rigid or younger than the larger (cohesionless) tumblers.An abundant population of binary systems has been found among NEAs. The fraction of binaries among NEAs larger than 0.3 km has been estimated to be 15 ± 4%. Primaries of binary systems concentrate at fast spin rates (periods 2–3 h) and low amplitudes, i.e., they lie just below the cohesionless spin barrier. The total angular momentum content in binary systems suggests that they formed from parent bodies spinning at the critical rate. The fact that a very similar population of binaries has been found among small main belt asteroids suggests a binary formation mechanism that may not be related to close encounters with the terrestrial planets.

scholarly journals PSYCHOLOGICAL PECULIARITIES OF SELF-DETERMINATION OF MODERN YOUTH

2021 ◽  
Vol 1 (13) ◽  
pp. 76-79
Author(s):  
Ivanna A. Shestopal
Keyword(s):  
The Self ◽  
Self Determination ◽  
Sensitive Period ◽  
Professional Activity ◽  
General Level ◽  
Life Plans ◽  
National University ◽  
Life Decisions ◽  
Modes Of Life

Adolescence is a sensitive period of an individual’s way of life projection through an ability of awareness its individuality and self-reflection, self-determination in social, personal, professional and other aspects of life, designing life plans and desire of conscious future’s planning. The purpose of the research is to determine psychological peculiarities of an ability to make a life choice in measuring the self-determination of the students. The self-determination of an individual is determination of the personal orientation vectors in different modes of life activity that is based on a life-sense search. The emergence of life plans in adolescence determines set for professional self-determination of youth that is involved in social production and labor activity that provides the process of “Me” ideas specification in a profession, career and professional plans. The study has been conducted at the National University of Ostroh Academy during 2019-2020. The sample was consisted of 50 respondents aged 20-25 at their 3rd-4th years of studying at different depatments and specialties. It has been diagnosed that the general level of modern youth’s ability to make own life choice is at a low level. During making important decisions, students have shown low ability to manifest independence in the process of self-determination, to resist the influence of others on this process. Due to the weakness of established life-based values, adolescents find it difficult to figure out optimal ways of their capabilities’ realization. Young people have demonstrated sufficient ability to analyze properly all aspects of the situation during making life decisions. Students have an inability of overcoming difficulties and obstacles in life, what prevent making balanced life decisions and the implementation of self-determination at the stage of choosing a profession and mastering professional activity. The inability of overcoming difficulties and obstacles fully prevents from own potential’s realization and taking opportunities, as well as making life balanced decisions, choices and perform self-determination of adolescents in general.

scholarly journals V 1500 Cyg: Slow Variability in Post-nova Stage

1990 ◽  
Vol 122 ◽  
pp. 68-70
Author(s):  
E. Pavlenko
Keyword(s):  
Ussr Academy ◽  
Crimean Astrophysical Observatory ◽  
Photometric Observations ◽  
The Mean ◽  
Academy Of Sciences

Regular photometric observations of V1500 Gyg (Nova Cygni 1975) have been carried out at the Crimean Astrophysical Observatory of the USSR Academy of Sciences from 1975 till now. The 0.5 m telescope equipped with a TV system is used to estimate the star brightness in V.The decline of the mean brightness is presented in Figure 1. The solid lines (1) and (2) show the changes of the V brightness according to Patterson (1979) and Arkhipova and Zaitseva (1978), respectively. The dotted line is drawn according to our data (Pavlenko 1988). The arrows indicate the amplitudes of the light and colour variations.

On the Measurement of Atmospheric Extinction by Rufener’s Method

1979 ◽  
Vol 3 (5) ◽  
pp. 326-327
Author(s):  
Z. KviZ
Keyword(s):  
Adverse Effect ◽  
Photometric System ◽  
Photoelectric Photometry ◽  
Atmospheric Extinction ◽  
Air Mass

The coefficient of atmospheric extinction may change during the night and in fact it often does. This has an adverse effect on the determination of atmospheric extinction by simple Bouguer plot of magnitude against air mass. This effect was studied by Rufener (1964), who introduced for the purpose of accurate photoelectric photometry in the Geneva photometric system the method of two ‘extinction stars’. His method consists of the measurement of two stars of the same colour — one starting at high air mass 2 - 3, the M-star (for French montante = rising) and the second starting simultaneously in the meridian at low air mass, the D—star (for descending).

scholarly journals Asteroids

1986 ◽  
Vol 118 ◽  
pp. 213-221
Author(s):  
H. J. Schober
Keyword(s):  
Physical Properties ◽  
Surface Properties ◽  
Spin Axis ◽  
Spectral Reflectivity ◽  
Topographic Features ◽  
Rotation Periods ◽  
Magnitude Range ◽  
Asteroid Body ◽  
Ubv Photometry ◽  
Phase Angles

Using a number of different conventional observing methods of astronomy like spectrophotometry, polarimetry, IR-radiometry and UBV-photometry, physical properties of asteroids can be derived, such as diameters, spectral reflectivity and albedo. Based on observable parameters a classification in terms of taxonomic types can be made and the mineralogy of the surface can be determined and compared with meteoritic analogues. UBV-photometry at different phase angles can reveal something about surface properties and diameters, whereas from accurate photometry during different phases of the rotational cycles we are able to derive rotation periods, geometric irregularities of the asteroid-body and topographic features on the surface. If observations of lightcurves are obtained during several oppositions at different ecliptic positions, the orientation of the spin axis in space and sometimes the sense of rotation can be derived. Observations of asteroids are especially well suited to small and medium-sized telescopes, as most of the programmes need long telescope runs. In addition there is a definite need for a large number of observations of asteroids in the magnitude range 12–15 mag.

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