ON  THE  SUN’S  MOTION  WITH  RESPECT  TO  NEARBY  STARS

ADINA  IONESCU 1,  MARIAN  DORU  ŞURAN 2

1 “Octav Onicescu” National College

Str. Trivale 29, Bucharest, Romania

E-mail: adina_2301@yahoo.com

 

2 Astronomical Institute of the Romanian Academy

Str. Cuţitul de Argint 5, 040557 Bucharest, Romania

E-mail: suran@aira.astro.ro

Abstract. We determine the Sun’s motion with respect to the neighbouring stars, using a kinematical selection obtained
via a
combination of Hipparcos catalogue and Barbier-Brossat catalogue of radial velocities. The Sun’ velocity is determined
by the methods of spatial velocities, radial velocities, and proper motions. We point out that there are no significant differences
between the results obtained by the application of these three methods. Because the results in literature were obtained via studies
made
on a limited number of stars, we consider a number of stars as large as possible, with known radial velocities and parallaxes.
Here we extend the previous results, determining the Sun’s motion with respect to stars situated at different distances. The Sun’s
velocity is also determined as function of the color index for the stellar population situated in the central region and for those stellar
populations
belonging to ZAMS, TAMS, and AGB regions.

Key words: stellar dynamics − Sun’s motion.

 

 

 

ESTIMATION  OF  ASTROPHYSICALLY  USEFUL PARAMETERS  FOR  SnF  AND  ScF  MOLECULES

PONSAMY  SRI  RAMACHANDRAN 1,  RAMACHANDRAN  SHANMUGAVEL 1,  NARAYANAN  RAJAMANICKAM 1, SOMASHEKAR  PUNDALIKARAO  BAGARE 2

1 Physics Research Centre, VHNSN College

Virudhunagar, 626 001, India

E-mail: nrmanickam@rediffmail.com

 

2 Indian Institute of Astrophysics

 Kodaikanal and Bangalore, 560 034, India

E-mail: bagare@iiap.ernet.in

Abstract. The calculation of Franck-Condon factors and r-centroids are of interest to study the electronic transition between bound
molecular states. Franck-Condon factors and r-centroid values estimated using the most reliable numerical integration procedure for
the bands of A2Σ − X2Π3/2, A2Σ − X2Π1/2, B2Σ − X2Π, C2Δ − X2Π3/2, and C2Δ − X2Π1/2 systems of the astrophysical molecule
SnF and B2Σ − X2Π3/2, CΣ − X2Π1/2, and E2Σ − X2Π, systems of ScF using a suitable potential
.

Key words: astrophysics− molecules SnF and ScF − Franck-Condon factors; r-centroids.

 

 

 

STUDY  OF  THE  MASSIVE  X-RAY  BINARY  LSI+65°010

DANA  VICAŞ,  JING-ZHI  YAN,  QING-ZHONG  LIU

Purple Mountain Observatory, Chinese Academy of Sciences, Space Astronomy

West Beijing Rd. 2, Nanjing, Jiangsu 210008, China

E-mail: dana.vicas@gmail.com

Abstract. We investigate the object LSI+65º010, a massive X-ray binary, using data that cover a ten-years period (1995−2005),
observed at the Xinglong station, Beijing Astronomical Observatory. First suggested by Liu and Hang (1999), we here find further
evidence to confirm the existence of an H II region around the neutron star.

Key words: astrophysics − X-ray binaries − neutron stars − accretion disks.

 

 

 

LIGHT-CURVE  VARIABILITY  OF  RZ  CEPHEI.  III.  OBSERVATIONS  1984–1985  PERFORMED  IN  CLUJ-NAPOCA

IOAN TODORAN,  ALEXANDRU  POP,  RODICA  ROMAN

Astronomical Institute of the Romanian Academy

Astronomical Observatory Cluj-Napoca

Str. Cireşilor 19, 400487 Cluj-Napoca, Romania

E-mail: apop@academie.cj.edu.ro, rroman@math.ubbcluj.ro

Abstract. Two observational data sets on the RRc star RZ Cephei obtained between November 1984 and October 1985 are presented and analyzed
through Fourier decomposition technique, and the Fourier-type structural parameters are computed. The variability of the light-curve shape is confirmed.

Key words: variable stars – RR Lyrae stars – light curve variability.

 

 

 

LIGHT-CURVE  VARIABILITY  OF  RZ  CEPHEI.  IV.  FEATURING  THE  LIGHT-CURVE  SHAPE

ALEXANDRU  POP,  RODICA  ROMAN

Astronomical Institute of the Romanian Academy

Astronomical Observatory Cluj-Napoca

Str. Cireşilor 19, 400487 Cluj-Napoca, Romania

E-mail: apop@academie.cj.edu.ro, rroman@math.ubbcluj.ro

Abstract. The aim of this paper is to give an accurate description of the light-curve shape of RZ Cephei, which proved to be featured by
some variability. Thus, we introduced a new class of structural parameters quantifying the skewness and the acuteness of the light curve.
They are defined as the relative length of given sections of the light curve. Their application to the case of RZ Cephei reveals their ability
to correctly detect those light curves that display strong distortions of their shape.

Key words: variable stars – RR Lyrae stars – light-curve shape variability.

 

 

 

ON  HOMOGRAPHIC  SOLUTIONS  AND  CENTRAL CONFIGURATIONS  OF  THE  n-BODY  PROBLEM

FERENC  SZENKOVITS,  VASILE  URECHE

Babeş-Bolyai University, Faculty of Mathematics and Computer Science

Astronomical Observatory Cluj-Napoca

Str. Cireşilor 19, RO-400487 Cluj-Napoca, Romania

E-mail: fszenko@math.ubbcluj.ro

 

Abstract. The concept of central configuration is important in the study of total collisions, in the relative equilibrium state of a rotating system
or in the variation of the topological type of the energy and angular momentum invariant manifolds in the n-body problem, in close connections
with homographic motions. In this paper, by using the variation of the moment of inertia, we characterize those particular solutions of the n-body
problem, in which the bodies form a central configuration at any moment of the motion, which are not necessary supposed to be homographic solutions.

Key words: n-body problem − central configurations − homographic solutions,

 

 

 

SEELIGER’S  TWO-BODY  PROBLEM:  COLLISION,  ESCAPE,  SYMMETRIES

VASILE  MIOC 1,  MIRCEA  RUSU 2

1 Astronomical Institute of the Romanian Academy

Str. Cuţitul de Argint 5, 040557 Bucharest, Romania

E-mail: vmioc@aira.astro.ro

 

2 University of Bucharest, Faculty of Physics

Str. Atomiştilor 1, CP MG-11, Bucharest-Măgurele, Romania

E-mail: mrusu@dnt.ro

Abstract. We offer a first insight into the two-body problem associated to the potential proposed by Hugo Seeliger at the end of 1800s.
Our goal is twofold: to describe two limit situations (collision and escape), and to emphasize the symmetries of the problem. First, we
resort to McGehee transformations to blow up the collision singularity and the (artificial) escape singularity, and to replace them by
manifolds pasted on the phase space. Then we describe the flows on these manifolds, which are useful to understand the behaviour of
nearby orbits. An important issue is that collision solutions are regularizable, whereas escape solutions are not regularizable. Finally, we
point out the symmetries that characterize the vector field in various coordinates. These symmetries form isomorphic Abelian groups
endowed with an idempotent structure, owing proper subgroups isomorphic to Klein’s group.

Key words: celestial mechanics – two-body problem – Seeliger’s theory of gravitation – collision − escape − symmetries.

 

 

 

ASSOCIATED  LEGENDRE  FUNCTIONS:  SYMBOLIC  COMPUTATION

MOHAMED  ADEL  SHARAF 1,  HADIA  HASSAN  SELIM 2,  ESSAM  AHMED  ELKHOLY 2

1 Department of Astronomy, Faculty of Science, King Abdul Aziz University

Jeddah, Saudi Arabia

E-mail: sharaf_adel@hotmail.com

 

2 Department of Astronomy, National Research Institute of Astronomy and Geophysics

Cairo, Egypt

E-mail: hadia@nriag.sci.eg, es_ah_el@yahoo.com

Abstract. In this paper we provide symbolic expressions for the associated Legendre functions Pl,m(sin φ) for any l and m, and for
any φ belonging to the interval (−90º, 90º). Numerical evolutions that use these expressions prove their extreme efficiency.

Key words: potential theory − Earth’s gravity − symbolic algebra.

 

 

 

PLANNING  NEAR-EARTH  ASTEROID  OBSERVATIONS  ON  A  1-METER  CLASS  TELESCOPE

OVIDIU  VĂDUVESCU 1, 2, 3,  MIREL  BIRLAN 2, 3

1 ACRU and SAAO, South Africa

Astrophysics and Cosmology Research Unit

University of KwaZulu-Natal, School of Mathematics

Durban, South Africa

E-mail: ovidiuv@yahoo.com

 

2 IMCCE, Observatoire de Paris

77, Avenue Denfert Rochereau, F-75014 Paris, France

 

3 Astronomical Institute of the Romanian Academy

Str. Cuţitul de Argint 5, 040557Bucharest, Romania

Abstract. The number of known Near-Earth Asteroids (NEAs) and Potentially Hazardous Asteroids (PHAs) has continued to grow
in the last decade. Follow-up and recovery of newly discovered objects, as well as new astrometry at second or third oppositions are
necessary to improve their orbits and predict any potential collision with the Earth in the future. A project to follow-up and recovery
PHAs and NEAs is proposed, using 1-meter class telescope in the next two years. Two incoming runs will take place first, at Pic du
Midi (France) and SAAO (
South Africa), both to use 1-meter telescopes. Other observing runs are sought in the future. Collaborators
to extend this project are welcome.

Key words: astrometry − NEAs − PHAs − CCD observations − star catalogs.