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,
E-mail: adina_2301@yahoo.com
2 Astronomical
Institute of the
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,
Virudhunagar,
626 001,
E-mail: nrmanickam@rediffmail.com
2 Indian Institute of Astrophysics
Kodaikanal and
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
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
IOAN
TODORAN,
ALEXANDRU POP,
RODICA
ROMAN
Astronomical
Institute of the
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.
ALEXANDRU POP, RODICA ROMAN
Astronomical
Institute of the
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
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
Str.
Cuţitul
de Argint 5, 040557 Bucharest, Romania
E-mail:
vmioc@aira.astro.ro
2 University
of
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,
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,
Astrophysics and Cosmology Research Unit
E-mail: ovidiuv@yahoo.com
2
IMCCE, Observatoire de
Paris
77,
Avenue Denfert
Rochereau, F-75014 Paris, France
3 Astronomical
Institute of the
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 (
to extend this
project are welcome.
Key words: astrometry − NEAs − PHAs − CCD observations − star catalogs.