THE LENSED QUASARS, TRACERS OF QUASAR'S EVOLUTION
DORU MARIAN SURAN, CRISTINA CARMEN POPESCU
Astronomical Institute of the Romanian Academy,
Str. Cutitul de Argint 5, 75212 Bucharest 28, Romania
Abstract. This paper presents the focus of the lensed quasars in the Hubble and colours quasar's diagrams. We discuss the different distribution of lensed quasars with respect to the lensing and evolutionary theory.
Key words: Quasars, Gravitational Lensing Effect, Evolutionary Effect.
STREAM MODEL FOR ECLIPSING BINARY SYSTEM RZ CANCRI
ALEXANDRU DUMITRESCU
Astronomical Institute of the Romanian Academy,
Str. Cutitul de Argint 5, 75212 Bucharest 28, Romania
Abstract. A linear stream model is used to explain the asymmetry of the primary minimum of the algoride RZ Cnc. The strong dependence of the asymmetry by ___, requires the Rayleigh scaterring adoption for the stream opacity. The transfer rate and stream mass were obtained: 0.17 x __________ and 0.65 x _____ respectively.
Key words: Eclipsing Binary Systems, Mass Transfer.
SOLAR PROTON EVENTS DURING THE SOLAR CYCLE 21: STATISTICAL ASPECTS
GEORGETA MARIS, SIMONA DINULESCU, SORIN POJOGA
Astronomical Institute of the Romanian Academy,
Str. Cutitul de Argint 5, 75212 Bucharest 28, Romania
Abstract: Solar proton events (SPEs) with the > 10 MeV maximum proton flux no less than 1 (cm² - s - sr)-² were considered (1976 - 1986). The association of SPEs with eruptive solar phenomena and coronal mass ejections (CMEs) was analysed. Special emphasis was placed on the relation between the characteristics of SPEs and the parameters of LDE IN soft X-ray and radio micowave burst (9 GHz). Geophysical effects as SSC, GLE, PCA, Forbush decreases (FD) were also considered for each SPEs. A comparison between the cases of SPEs associated with a CMEs and the cases of single SPEs was done.
Key words: the Sun, Solar Protons, Flares.
GEORGETA MARIS
Astronomical Institute of the Romanian Academy
Str. Cutitul de Argint 5, 75212 Bucharest 28, Romania
Abstract. The sunspot relative number presents the longest and the most complete series of data about one of the solar activity phenomena. Its behaviour permitted to reveal eleven years cycles with maxima and minima which periodically are succeeding. Rarely some cycles present a double maximum. At present the solar activities are marked with many other indices which characterize the energetic flares, the electromagnetic or corpuscular radiation, the coronal phenomena. Some of them reveal double maxima or secondary maxima during the descending phase of the eleven years solar cycle.
Key words: Solar activity (SA), 11 Years Cycle of SA, Maximum of SA.
THE DISTRIBUTION OF RECURRENT GEOMAGNETIC STORMS IN COMPARISON WITH HSPS DURING THE MINIMUM PHASE OF THE SOLAR CYCLE 21
SIMONA DINULESCU, VASILE DINULESCU
Astronomical Institute of the Romanian Academy,
Str. Cutitul de Argint 5, 75212 Bucharest 28, Romania
Abstract. In this paper we made a statistical analysis of the geomagnetic storms and High Speed Plasma Streams (HSPS). It is shown that the recurrent storms appear especially during the three preceding days of an HSPS.
Key words: the Sun - Solar Wind - Geomagnetic Storms
APPROXIMATION OF ALTITUDE-DEPENDENCE OF THE DENSITY SCALE HEIGHT
LUCIAN BURS
Astronomical Institute of the Romanian Acdemy,
Astronomical Observatory Timisoara,
P-ta Axente Sever 1, 1900 Timisoara, Romania
Abstract. The paper tries to find an empirical formula to approximate the height-dependence of the density scale height (in the case of a spherically-symmetrical terrestrial atmosphere), for a given epoch and for a given solar and geomagnetic activity, such that the density calculated with the classical exponential formula approximate a given model with a relative error lower than 0.05% (condition ensured by the program). The parabolic variation (on intervals) of the density scale height with the altitude was chosen. The numerical applications were performed for the CIRA 1972 atmospheric model and for three levels (minimal, mean,maximal) of solar and geomagnetic activity.
Key words: Terrestrial Atmospheric Density - Density Scale Height.
ORBIT CHANGES IN MARS' LOWER ATMOSPHERE
VASILE MIOC, CRISTINA BLAGA, EUGENIA RADU
Astronomical Institute of the Romanian Academy
Astronomical Observatory Cluj-Napoca
Str. Ciresilor 19, 3400 Cluj-Napoca, Romania
Abstract. Using Sehnal's exponential law to describe the density distribution in Mars' atmosphere at heights up to 100 km, the first order drag perturbations in the motion of an orbiter evolving in this height range are analytically determined over one nodal period. Mars' oblateness and its atmospheric rotation are considered. The analytic approach of passive trajectories at such altitudes is justified.
Key words: Mars' Atmosphere - Orbital Motion.
ROTATION GRAVITATIONAL EFFECTS TESTING BY MEANS OF A CIRCULAR GYROSCOPE
ZOLTAN GABOS
University of Cluj-Napoca,
Str. M. Kogalniceanu 1, 3400 Cluj-Napoca, Romania
Abstract. The gravitational action of a rotating , rigid, spherical central body is studied in the case in which the test particle is a circular gyroscope. The motion equations are established, and different particular cases are discussed.
Key words: Gravitation
EXTENSION OF A METHOD FOR NODAL PERIOD DETRMINATION IN PERTURBED ORBITAL MOTION
VASILE MIOC
Astronomical Institute of the Romanian Academy
Astronomical Observatory Cluj-Napoca
Str. Ciresilor 19, 3400 Cluj-Napoca, Romania
Abstract. The method proposed by Zhongolovich to estimate the first order variations in the nodal period of a test body in perturbed orbit around an attractive centre is extended to second order perturbations. The results are general from two viewpoints : the nature of the perturing factor remains unspecified, and the total eccentricity may have any subunitary value. The obtained accuracy, of second order with respect to the small parameter fetauring the perturbing factor, can be needed by various astronomical situations in which the factor acts sufficiently strongly.
Key words: Perturbed Orbital Motion - Nodal Period.
CAMPAIGN PHEMU- 91 : MUTUAL EVENTS OF THE GALILEAN SATELLITES OBSERVED IN ROMANIA
G.OPRESU, A. DUMITRESCU, M.D. SURAN
Bucharest Observatory, Romania
D. CHIS, V. TURCU
Cluj-Napoca Observatory, Romania
L. BURS, O. GHEREGA, L. FARKAS, A. HORVATH
Timisoara Observatory, Romania
Abstract. During the PHEMU - 91 campaign, eight mutual events have been observed in Romania. The observations were performed by photoelectric methods. The minima times for the light curves were determined.
Key Words: Solar System, Galilean Satellites.
ON THE CORRECTIONS OF THE STARS OBSERVED AT THE TIME SERVICE - BUCHAREST
MONICA CIOBANU, MAGDALENA STAVINSCHI, DANA DINESCU
Astronomical Institute of the Romanian Academy
Str. Cutitul de Argint 5, 75212 Bucharest 28, Romania
Abstract. Processing of observational data is presented for 185 stars from 240 of Pugliano programme. The observations were performed with a passage instrument during 1980 - 1983.
Key words:Data Processing, Time Determination.
HU TAU - AN UNUSUAL ECLIPSING BINARY SYSTEM : PHOTOMETRY AND SOLUTIONS
ALEXANDRU DUMITRESCU, MARIAN D. SURAN
Astronomical Institute of the Romanian Academy,
Str. Cutitul de Argint 5, 75212 Bucharest 28, Romania
Abstract Using the light curves performed at Bucharest Observatory in the 1974 - 1976 period the authors have computed the photometric elements of the system. The Wood model was used . The solution indicate an occultation in the primary minimum.
A comparison with other sets of solutions given by Dumitrescu & Dinescu (1980) and Giuricin & Mardirossian (1981) is presented.
Key words: Eclipsing binary systems, photometric solutions.
SEMI-OPAQUE THIOK DISKS IN W SER-TYPE BINARIES ; APPLICATION TO SX CAS
ALEXANDRU DUMITRESCU, MARIAN D. SURAN , GHEORGHE VASS
Astronomical Institute of the Romanian Academy,
Str. Cutitul de Argint 5, 75212 Bucharest 28, Romania
Abstract. Using the Wood's method and light curves observed by Koch (1972), the relative and absolute elements of the eclipsing binary SX Cas were obtained. A large and cold accretion disk around the primary star is taken into account. From the duration of the secondary minimum the radius of the disk has been obtained. Considering a power law for the density distribution along the disk, the Rayleigh scattering as a main source of opacity and no eemission from disk (this one is seen edge-on) the authors have obtained the absolute dimensions and the mass of the accretion disk.
Key words: eclipsing binary systems, accretion disks.
QUASIHELIOSTROPHIC AND AUASIMAGNETOSTROPHIC ASYMPTOTIC APPROXIMATIONS BY SCALE ANALYSIS
MIHAI GHIZARU
Astronomical Institute of the Romanian Academy
Abstract. The regular perturbation method for ideal MHD dimensinless equations (written in spherical coordinates) is used in order to describe a large-scale hydromagnetic flow on a rotating sphere.
First and second order approximations for two different orders of magnitude of Alfvén-Mach number and plasma beta are presented.
Quasiheliostrophic and quasimagnetostrophic equations are obtained in second order asymptotic approximations. The former equations could describe the large-scale hydromagnetic photospheric flow, especially the nonlinear interaction between Rossby and Alfvén waves. The last equations could describe a dynamo model for the interface between solar radiative interior and convection zone.
Key words: MHD equations, regular perturbations, plasma beta, Alfvén-Mach number.
ON THE CORRELATION BETWEEN WOLF' NUMBERS AND THE BARYCENTRIC DISTANCE OF THE SUN
IERONIM MIHAILA
Bucharest University, Faculty of Mathematics,
Str. Academiei 14, Bucharest, Romania
NEDELIA POPESCU
Astronomical Institute of the Romanian Academy ,
Str. Cutitul de Argint 5, Bucharest, Romania
Abstract . The correlation between Wolf's sunspot numbers and the barycentric distance of the Sun from 1755 to 1986 (cycles 1 - 21) is studied. The correlation is weak, the correlation coefficient being 0.110 ±0.065. The correlation is also weak for the epochs of the maxima and minima. The proportionality found by Dauvillier for the epochs of maxima is not confirmed.
Key words: solar activity, sunspots, planetary influences.
SPLINE TECHNIQUES IN EMPIRICAL DATA FITTING
VASILE POP
University of Cluj-Napoca
Str. M. Kogalniceanu 1, 3400 Cluj-Napoca, Romania
CRACIUN IANCU
Mathematical Institute Cluj-Napoca
Str. Republicii 37, 3400 Cluj-Napoca, Romania
TIBERIU OPROIU
Astronomical Institute, Astronomical Observatory Cluj-Napoca
Str. Ciresilor 19, 3400 Cluj-Napoca, Romania
Abstract. The advantages of the use of splines to approxiamte analytically tabularly given empirical functions met in phenomena modelling are emphasized. Algorithms for the construction of three types of fitting splines (based on divided differences, Yoshimoto-type, and Hiroshi-type) are given. Applications of these techniques to concrete astronomical problems (light curves of variable stars, internal structure of relativistic stars) are presented, too.
Key words: data fitting - splines.
EVOLUTION OF SATELLITE ORBITS IN AN ATMOSPHERE WITH NORTH - SOUTH ASYMMETRY
VASILE MIOC and EUGENIA RADU
Astronomical Observatory Cluj-Napoca
Str. Ciresilor 19, 3400 Cluj-Napoca, Romania
Abstract. The separate influence of the North-South asymmetry in the high atmospheric density distribution (described by the TD thermospheric model) on the orbital parameters of an artificial satellite, during one nodal period of this one, is analytically estimated. Particular cases are taken into account.
Key words: artificial satellites - atmospheric drag perturbations - TD thermospheric model.
ON THE DYNAMICS OF EARTH'S INSTANTANEOUS AXIS OF ROTATION
MAGDA STAVINSCHI and DANA DINESCU
Astronomical Institute of the Romanian Academy
Str. Cutitul de Argint 5, 75212 Bucharest, Romania
Abstract. The paer presents the deducing of the theoretical ellipse of the instantaneous pole's motion and its determination frm Doppler tracking of Transit satellite 1967 - 921 during 1981 - 1984.
Key words: Earth's rotation
ON THE MOTION OF A FREE PARTICLE IN KINEMATIC RELATIVITY
IOAN ANTONIU POPESCU
National Institute of Meteorology and Hydrology
Bucharest, Romania
Abstract. From the viewpoint that Milne's Kinematic Relativity is a fundamental theory of matter in all domain, from elementary particle physics tocosmology, we study the problem of a free particle in the presence of the Universe at large, in the classical and quantum pictures. We formulate the Hamilton-Jacobi, Dirac, and Kelin-Gordon equations for a free particle in the presence of the Universe at large. The form of these equations suggests that Kinematic Relativity is more suitable to serve as a basis for a description of the Early Universe than the ordinary relativistic and quantum theories of contemporary physics.
Key words: Kinematic Relativity, Hamilton-Jacobi equation, Dirac equation, Kelin-Gordon equation, free particle in the presence of the Universe at large.
NOTE ON THE USE OF UNITS IN AN ARTIFICIAL SATELLITE DYNAMIC PROBLEM
CATALIN CUCU-DUMITRESCU
Institute of Gravitation and Space Sciences,
Bd. Ana Ipatescu, 21, Bucharest, Romania
Abstract. This note presents some considerations concerning the use of units in the problem of precession and nutation effect on the artificial satellietes' motion. In this problem there are variables which have uncorrelated universally accepted units.
Because of that in Kozai's paper (1960) there are some hermetical
passagzs which become clear in the present note.
OBSERVATIONS OF MINOR PLANETS IN 1986 - 1990 IN BUCHAREST
A.ALEXIU, G. BOCSA, M. STANESCU
Astronomical Institute of the Romanian Academy,
Str. Cutitul de Argint 5, 75212 Bucharest 28, Romania
Abstract. In this paper there are presented the observations of minor planets obtained in 1986 - 1990, with a 380/6000 mm astrograph. The measurements of the plates were carried out by means of a ASCORECORD measuring machine. Both Turner's (constants) and Schlesinger's (dependences) methods are used for the computation of the normal coordinates of the object.
Key words: Astrometric positions of the asteroids.