ANALYTICAL
SOLUTION OF ABEL’S
EQUATION FOR
STELLAR DENSITY
IN
GLOBULAR CLUSTERS
MOHAMED
ADEL SHARAF 1, AMR A. SHARAF 2, HADIA SELIM 3
1Department
of Astronomy, Faculty of Science, King Abdul Aziz University
Jeddah,
Saudi
Arabia
E-mail:
sharaf_adel@hotmail.com
2Department
of Computer Science, Faculty of Science, King Abdul Aziz University
Jeddah, Saudi
Arabia
3Department
of Astronomy, National Research Institute of
Astronomy
and Geophysics
Cairo,
Egypt
E-mail:
hadia@gmca.eis.uva.es
Abstract. We establish a
bi-parametric analytical solution to
Abel’s
integral equation for stellar density in globular clusters. The
solution can be
used
for an arbitrary order of outward decrease of the cluster density.
Key
words: stellar clusters – Abel’s equation.
COSMIC
RAYS ACCELERATION IN
WOLF-RAYET STELLAR
WINDS
ADRIAN
SABIN POPESCU
Astronomical
Institute of the Romanian Academy
Str.
Cuţitul de
Argint 5, RO-040557 Bucharest, Romania
E-mail:
sabinp@aira.astro.ro
Abstract. Popescu et al.
(2004) gave a model for the observed
cosmic rays
between 
and 
eV. Their source is
presumed
to be the supernova of stars that explode in their winds. The observed
cosmic rays abundance at the source are affected by spallation
in the supernova
shell, by the difference in ionization degree (being one or two times
ionized)
at the injection in the supernova shock,
the stars with initial masses 15MSun ≤ M ≤ 30MSun
having a different contribution to
them than the stars with 30MSun
≤ M ≤ 50MSun,
this being 2:1 for the elements with Z ≥ 6. Still,
the abundances after these
corrections are different by a factor 
,
where 
is
the
atomic number for the element i. This paper is
dedicated to the explanation of this factor and
its physical meanings by considering that,
prior to the shock injection, the
wind particles are radiative accelerated.
Key
words: cosmic rays – radiative
acceleration – Wolf-Rayet stars.
NEW
V LIGHT CURVE
AND EPHEMERIS OF
THE BINARY SYSTEM
44i BOOTIS
Magdy M.
Elkhateeb, Mohamad I.
Nouh, Somaya M. Saad,
Hadia Selim
Department
of Astronomy, National
Research
Institute of Astronomy and Geophysics (NRIAG)
Helwan,
Cairo, Egypt
E-mail: abdo_nouh@hotmail.com,
hadia@gmca.eis.uva.es
Abstract. This paper presents the results of the photometric
observations of
the W UMa-type eclipsing binary 44i Bootis in V band,
carried out in 1992. A
complete light curve together with times of minima was obtained. Light and period variations of the system are
also
discussed.
Key
words: stellar photometry –44i Bootis.
FILAMENTS
DIFFERENTIAL ROTATION
BEHAVIOR WITHIN THE
SOLAR CYCLE
CRISTIANA
DUMITRACHE
Astronomical
Institute of the Romanian Academy
Str.
Cuţitul de
Argint 5, RO-040557 Bucharest, Romania
E-mail:
crisd@aira.astro.ro
Abstract. A study of
filaments observed during 1957–1989 reveals
that the
differential rotation velocity changes within the solar cycle.
We suggest that
these variations are the manifestation of the torsional oscillations of
the
coronal magnetic field.
Key
words: Sun – filaments – differential
rotation.
COMMON
PERIODICITIES IN
SOLAR ACTIVITY
AND
EARTH ROTATION
GEORGETA
MARIŞ,
VASILE MIOC, ADRIAN ONCICA, MAGDA STAVINSCHI
Astronomical
Institute of the Romanian Academy
Str.
Cuţitul de
Argint 5, RO-040557 Bucharest, Romania
E-mails:
{gmaris,
vmioc, adrian,
magda}@aira.astro.ro
DANIEl
GAMBIS
Observatoire
de
Paris, 61 Av. de l’Observatoire, F-75014 Paris, France
E-mail:
Daniel.Gambis@obspm.fr
Abstract. We point out some
periodicities
common to the solar activity and to the Earth’s rotation, characterized
by the
length of the
day (LOD). The behavior of the LOD time series was analyzed
through the “time-frequency distribution” approach. The QBO oscillation
(the 26
months period - 0.46 cycles/year) and 10.5
years
(0.095 cycles/year) cycles of solar variability are present in the LOD
data
spectrum, but, due to short (only 42 years) time span of the data, the
“11-year” solar feature is to be taken cautiously. In the LOD plot
the two
maxima between three minima over the 42 years time span may be fitted
with a
44-year period of 0.7 ms amplitude and a 20-year
period of 0.7 ms amplitude.
Key words:
solar activity - Earth’s rotation– length
of the day.
LIBRATION
POINTS IN MANEV’S
PHOTOGRAVITATIONAL CIRCULAR
RESTRICTED THREE-BODY PROBLEM
RODICA
ROMAN1, VASILE
MIOC2
1Astronomical
Institute of the Romanian Academy
Astronomical
Observatory Cluj-Napoca
Str.
Cireşilor 19, RO-3400 Cluj-Napoca, Romania
E-mail:
rroman@math.ubbcluj.ro
2Astronomical
Institute of the Romanian Academy
Str.
Cuţitul de
Argint 5, RO-040557 Bucharest, Romania
E-mail:
vmioc@aira.astro.ro
Abstract. We tackle the
photogravitational circular restricted
three-body
problem in Manev’s gravitational field. The only aspect we examine is
the
existence
and location of libration points. For such points in the motion plane
of the primaries, we find both collinear and triangular equilibria. In
the
latter case, triangles
are scalene in general, but isosceles and even
equilateral configurations are emphasized, too. Outside the motion
plane of
primaries, some cases of existence
of libration points are pointed out, but
many mathematical arguments are to be added. We find degenerate
equilibria both
on the line determined by the primaries
and in the plane generated by this
line.
Key
words: celestial mechanics – restricted
three-body problem –
photogravitational problems – post-Newtonian fields – Manev’s model.
SPLITTING
OF THE PPN
(1+2)-BODY PROBLEM: A
POSSIBLE BASIS
FOR
A GRT EXPERIMENT
DAN
ŞELARU1, VASILE MIOC2,
CĂTĂLIN CUCU-DUMITRESCU1, MARIAN GHENESCU1
1Institute
of Space Sciences
Str.
Mendeleev 21-25, RO-701681 Bucharest, Romania
E-mails:
danselaru@yahoo.com,
cucudumitrescu@yahoo.com,
mariang@softrust.ro
2Astronomical
Institute of the Romanian Academy
Str.
Cuţitul de
Argint 5, RO-040557 Bucharest, Romania
E-mail:
vmioc@aira.astro.ro
Abstract. The Hamiltonian
of the (1+2)-body problem (a close
binary and a
far massive body) is presented in the PPN formalism. Within the
framework
of a
relativistic physical model, the (1+2)-body problem splits into two
perturbed
two-body problems: the motion of the binary barycenter with respect to
the
massive body, and the relative motion in the binary. Transposing the
latter
problem into a co-moving frame, the Hamiltonian becomes autonomous.
Conclusions
are formulated as regards the possibility of a GRT experiment within
this
framework.
Key
words: celestial mechanics – relativity –
PPN framework –
bi-planetary
problem.
ASTRONOMICAL
REFRACTION CALCULATION FOR
THE EARTH’S ELLIPSOIDAL
ATMOSPHERE
IERONIM
MIHĂILĂ, MINODORA
LIPCANU
University of Bucharest, Faculty of Mathematics and Computer Science
Str.
Academiei 14, RO-010014 Bucharest, Romania
E-mail: mihaila@math.math.unibuc.ro, mlipcanu@xnet.ro
Abstract. We calculate the
astronomical refraction in the
meridian plane of
the place for the ellipsoidal atmosphere of the Earth. We show that the
Laplace-Oriani theorem is also valid for the considered model. By
comparing
these results to the ones of the spherical model, it is ascertained
that
the
refraction calculated for the ellipsoidal model is greater than the one
for the
spherical model, the difference increasing with the zenith distance and
depending on the latitude of the place.
Key
words: astrometry – astronomical
refraction - atmospheric models.
OBSERVING
NEAR EARTH ASTEROIDS
WITH
A SMALL TELESCOPE.
I.
PLANNING THE OBSERVATIONS
OVIDIU
VĂDUVESCU1, 2
1
York University,
Department of Physics and Astronomy
128
Petrie Science Building, 4700 Keele St., Toronto, M3J 1P3 Ontario, Canada
E-mail:
ovidiuv@yorku.ca
2
Astronomical Institute of the Romanian Academy
Str.
Cuţitul de
Argint 5, RO-040557 Bucharest, Romania
E-mail:
ovidiuv@yahoo.com
Abstract.
Even from a
light-polluted city it is possible to observe Near Earth Asteroids
(NEAs) at
opposition using a small telescope equipped with a
CCD camera. In this paper we
review the major NEA programs and present the planning of the follow-up
observations using a small facility. In a
second paper we will present the
first results of a program run at York University Observatory.
Key
words: astrometry – NEAs – PHAs – CCD
observations – star
catalogs.
VENUS’
TRANSIT OF 1874
OBSERVED IN ROMANIA
MAGDA
STAVINSCHI
Astronomical
Institute of the Romanian Academy
Str.
Cuţitul de
Argint 5, RO-040557 Bucharest, Romania
E-mail:
magda@aira.astro.ro
Abstract. Venus’ transit
across the solar disk in 1874 was
observed in Romania,
too. We present the Romanian (Neculai Culianu and Ştefan Micle)
and Austrian
(Theodor von Oppolzer and Edmund Weiss) personalities who observed the
transit,
as well as the event as seen from Jassy.
Key words:
history of
astronomy – Venus’
transit.