100 YEARS OF THE BLAZHKO PHENOMENON: IS THE SOLUTION IN SIGHT ?
KATRIEN KOLENBERG 1,2
1.Institut
für Astronomie, University of
Vienna
Türkenschanzstrasse
17, A-1180 Vienna, Austria
E-mail:
kolenberg@astro.univie.ac
2
Instituut voor
Sterrenkunde
Celestijnenlaan
200D, B-3001
Abstract. The Blazhko
effect is a periodic amplitude and/or phase modulation
of the light curve, shown by a large fraction
of the astrophysically important
RR Lyrae stars. Despite numerous observational studies and elaborate
models
attempting
to reproduce the modulation, it still defies a definitive
explanation. In this paper, I attempt to present a brief overview of
the
phenomenon, outline the proposed explanations, and conclude with the
present
status of research.
Key words: variable stars – pulsating stars – RR Lyrae stars.
THE CONTROVERSIAL
CASE OF FK
COMAE BERENICES
KIRIL Panov, DINKO
Dimitrov
72
Tsarigradsko Shossee, 1784 Sofia, Bulgaria
E-mail:
kpanov@astro.bas.bg,
dinko@astro.bas.bg
Abstract. We used the
1991–2005 observations of FK Com performed in Rozhen
NAO, Bulgaria, added to existing data, to
construct a data set in V for the period 1966–2005.
The study of
the light curves pointed out a model with three spots: one
detected in the
whole data set, and two smaller, occasionally present.
Key words: variable stars – spots – FK Com.
VARIABLE-SINE ALGORITHMIC
ANALYSIS (VSAA):
APPLICATIONS TO AB
ANDROMEDAE
AND
TO THE WOLF’S
SUNSPOT NUMBER
SOTIRIOS TSANTILAS, hELEN ROVITHIS-LIVANIOU
Department
of Astrophysics-Astronomy and
Mechanics, Faculty of Physics,
Panepistimiopolis,
Zografos 157 84, Athens, Greece
E-mail:
stsant@phys.uoa.gr,
elivan@phys.uoa.gr
Abstract. In many cases
astrophysical phenomena exhibit non-constant
periodicities or quasi-periodic terms. These phenomena
are usually interpreted
via either Fourier Transforms or Wavelet Analysis. Although this
interpretation
with a set of constant periods
is inadequate, as any traced frequency seems to
be modulated through time, these two methods are widely used. In this
work, we
present a new algorithmic method of time-series analysis, based on the
idea of
a single variable sine function. Moreover, we have
applied it to data analysis
of an active contact binary, i.e. AB And, acquiring its subsurface
magnetic
field, and to the Wolf’s sunspot
number. The method can also be implemented in
various other topics of applied sciences.
Key words: data analysis – eclipsing binary systems – sunspots.
ORBITAL PERIOD CHANGES IN CONTACT BINARIES
DANAE BISSYLLA, ELENI ROVITHIS-LIVANIOU
Department of Astrophysics-Astronomy and Mechanics, Faculty of Physics
National
and
Panepistimiopolis,
Zografos 157 84, Athens, Greece
E-mail:
elivan@phys.uoa.gr
Abstract. Orbital period
changes of contact binaries are examined, on the basis of observational
data of
93 such systems.
The sample includes early spectral type, E, as well as late
spectral type, W UMa-type, contact binaries with a large range of
filling
factors: from 2% till 85%. The secular orbital period variations, dP/dt,
for most of the
systems, were found to be of the
order of 10–7 d/y. 25% of the systems of
our sample seem to be at least triples.
Key words: close binaries – contact systems – (O–C) diagrams – orbital period changes.
MASS TRANSFER RATES IN ALGOLS AND SECULAR PERIOD CHANGES IN RS CVn-TYPE SYSTEMS
DANAE ANTONOPOULOU,
ALEXANDROS PAPAGEORGIOU, SOTIRIOS
TSANTILAS, ELENI
ROVITHIS-LIVANIOU
Department
of Astrophysics-Astronomy and
Mechanics, Faculty of Physics,
Panepistimiopolis,
Zografos 157 84, Athens, Greece
E-mail:
elivan@phys.uoa.gr
Abstract. In this preliminary
paper we examine two subjects. First, the mass transfer rates in
Algol-type binaries
based on the analysis
of their observational data. The result was to confirm
that this is done in a Kelvin-Helmholtz time scale. Second, the secular
orbital
period
changes of RS CVn-type binaries. Our results show that: (1) most of
them
do not exhibit any variation; (2) some variation appears for:
(2a) great values
of the mass-ratio, (actually after a critical value of 0.78); (2b) for
primary
temperatures smaller than 5000 K, or
(2c) for secondary temperatures greater
than 5500 K.
Key words: close binaries – Algol and RS CVn-type binaries – mass transfer – orbital period changes.
FLARE
ACTIVITY OF AD LEO IN
THE PERIOD 2006–2007
RENADA KONSTANTINOVA-ANTOVA1, RUMEN BOGDANOVSKI
2,3,
ALEXANDAR
ANTOV 1, BORISLAV
SPASSOV 1
1 Institute of
Astronomy,
72
Tsarigradsko Shosse, Sofia 1784, Bulgaria
E-mail:
antovi@astro.bas.bg
2 Institute of
Mathematics and Informatics,
Acad.
G. Bonchev Str., block 8,
3 Space Research
Institute,
6
Moskovska Str., Sofia 1000,
E-mail:
rumen@skyarchive.org
Abstract. AD Leo has been
observed in 2006 and 2007 during campaigns of
simultaneous observations at the Bulgarian National
Astronomical Observatory in
Rozhen and the Observatory in
U-band has been
carried out. Enhanced flare activity was observed between January and
March
2006; optical oscillations were
detected during a large flare in March 2007.
Key words: variable stars – flare stars – photometry.
IS EM CEP A BINARY SYSTEM OR A SHORT-PERIOD CEPHEID?
Ia Kochiashvili1,
Nino Kochiashvili2
1
E-mail:
ia_ko17@yahoo.com
2
Georgian National Astrophysical Observatory
Kazbegi
ave. 2a, 0160
E-mail:
dianoz@yahoo.com
Abstract. EM Cep is a B spectral
type giant. The character of its luminosity variability attracts
attention of
astronomers since 1959.
It is considered as a close binary system. The star is
observed at Abastumani Observatory since 1991. We have solved its light
curves
using the Wilson-Devinney code. The parameters obtained are absolutely
acceptable,
but they are not in agreement with
the existing spectral data. Opinion exists
that the star maybe l Eri type short-period Cepheid. Due to this fact
we
revised our
observations. A conclusion is drawn that the high-resolution
spectral observations are necessary for solving this problem: is EM Cep
a
binary system or a short-period Cepheid?
Key words: variable stars – close binary systems – short-period Cepheids.
THE LIGHT-TIME EFFECT IN THE ALGOL-TYPE ECLIPSING BINARY UZ SAGITTAE
ALEXIOS LIAKOS, PANAGIOTIS NIARCHOS
National
and
Department of Astrophysics, Astronomy and Mechanics,
Panepistimiopolis, GR 157 84 Zografos,
Athens, Greece
E-mail:
alliakos@phys.uoa.gr,
pniarcho@phys.uoa.gr
Abstract. New times of
minimum light of the Algol-type eclipsing binary UZ
Sagittae, obtained at the Athens University Observatory,
have been used
together with all reliable timings found in the literature in order to
study
the period variation and search for the presence
of a third body in the system.
Its O–C diagram is presented and apparent period changes are discussed
with
respect to possible
Light-Time Effect (LITE) in the system. A least-squares
method has been used to compute new light elements (an updated
ephemeris
of the
binary), as well as the mass function, its minimum mass, and the period of a
possible third body.
Key words: variable stars – eclipsing binaries – light-time effect – UZ Sge – period variations – O–C diagram analysis.
V1025 HERCULI AND V1071 HERCULI: BVRI PHOTOMETRY AND COLOR INDICES ESTIMATION
Giannis KONTOGIANNIS, NIKOLAOS NANOURIS, EUGENIA ANTONOPOULOU, GIANNIS GIANNIKAKIS
Section of Astrophysics, Astronomy and Mechanics
Physics
Department,
Panepistimiopolis
Zografou, GR-1784
E-mail:
gkontog@phys.uoa.gr
Abstract. We present BVRI observations of
two not previously
studied eclipsing binary stars. A significant number of times of minima
were
determined and therefore new, more accurate, ephemerides were produced.
Neither
photometric elements nor spectral types for
these two variable stars were
known, thus a first approximation of their effective temperature and
absolute
magnitude was made by
means of standard stars absolute photometry and using
appropriate Teff, Mv – color
index empirical relations.
Key words: eclipsing binary systems – photometry – V1025 Her – V1071 Her.
FLARE PROCESSES IN DIFFERENT TYPE STARS
REZO NATSVLISHVILI, NINO KOCHIASHVILI
Georgian National Astrophysical Observatory
Kazbegi
ave. 2a, 0160,
E-mail:
rezonats@yahoo.com,
dianoz@yahoo.com
Abstract. In this paper we
present a characterization of flare
events of different
spectral type stars. The flare events were observed by
the authors at the Astrophysical
Observatories of Abastumani (Georgia) and Byurakan (
during about 30 years. The respective data consist of photographic,
electro-photometrical and spectral observations. The type of flares
observed, as
well as the character of their course, enable the authors to present a
possible
mechanism of flares. The authors consider that
it is possible to verify the
mechanism by special planned observations.
Key words: flare events – flare stars – mechanism of flares.
THEORETICAL RELATION BETWEEN OSCILLATION FREQUENCIES OF DISTORTED AND UNDISTORTED POLYTROPIC STARS
BURAK ULAŞ, OSMAN DEMİRÇAN
17100,
E-mail: bulash@gmail.com, demircan@comu.edu.tr
Abstract. Theoretical
relation between the frequencies of oscillation in
distorted and undistorted polytropic stars is investigated. Small
perturbations
were applied to related equation given by Chandrasekhar (1933) for
tidally and
rotationally distorted stars. For a given stellar model it is possible
to
find
a relation between the frequencies of oscillations created somewhere
inside the
star with a given amplitude.
Key words: astrophysics – stars – binary systems – polytropes – oscillations.
THE β LYRAE-TYPE ECLIPSING BINARY EG CEP: NEW BVRI PHOTOMETRY AND MODELLING
CHLOI VAMVATIRA-NAKOU, ALEXIOS
LIAKOS, VASSILIOS
MANIMANIS,
PANAGIOTIS
NIARCHOS
Department
of Astrophysics, Astronomy and
Mechanics,
GR 157
84 Zografos,
E-mail:
pniarcho@phys.uoa.gr
Abstract. New BVRI
CCD observations of the semi-detached eclipsing binary EG Cep are
presented.
The observed light curves
are analyzed with the Wilson-Devinney program and new
geometrical and photometric elements are derived. These elements are
used
to
compute the physical parameters of the system in order to study its
evolutionary status.
Key words: variable stars – eclipsing binary systems – data analysis – EG Cep.
SHORT-TERM VARIABILITY OF THE DWARF NOVA SS CYGNI DURING THE OUTBURSTS
IRINA Voloshina 1, ELENI Rovithis-Livaniou 2, VLADIMIR Metlov 1
1
Sternberg Astronomical Institute,
Universitetskij
prospekt 13, Moscow 119992,
E-mail:
vib@sai.msu.ru
2 Department
of Astrophysics-Astronomy and Mechanics, Faculty of
Physics,
Panepistimiopolis,
Zografos 157 84, Athens, Greece
E-mail:
elivan@phys.uoa.gr
Abstract. SS
Cyg is a
well-known classical dwarf nova. For this class of cataclysmic
variables, the
short-term variability during the
maximum and decline after it are typical:
from the most rapid and coherent dwarf nova oscillations (10–30 sec
periods,
DNOs) to
quasi-periodic oscillations (1–30 min, QPOs).
Here we report the results of our CCD and broad-band
photometric observations
of SS Cyg
carried out with the telescopes in
during the 2006 outburst revealed oscillations with the two periods 10
sec and 76 sec. Moreover, the
analysis of our photometric
data taken during another outburst of SS Cyg
show the existence of periodic
oscillations on the stage of decline after maximum, too.
Key words: CVs – dwarf novae – photometry – quasi-periodic oscillations – SS Cyg.
STUDY OF THE RECURRENT NOVA RS OPHIUCHI
IRINA VOLOSHINA
1,
VLADIMIR METLOV 1,
LUDMILA LARIONOVA 2,
TATIANA
KONSTANTINOVA 2
1 Sternberg
Astronomical Institute,
Universitetskij
prospect 13 ,119992
E-mail:
vib@sai.msu.ru
2 Sobolev
Astronomical Institute,
Abstract. We present new
CCD observations of the recurrent nova RS Oph
performed during August and September 2007 in
Crimea to study its photometric
variability in detail. The analysis of all our observations, including
the
early performed ones in
April 2007 (2048 measurements), reveals a periodic
oscillation with 32.742 min period, besides the flickering with an
amplitude
of
~0m.2 on a time scale of minutes. The consideration of the
detected
variation properties shows that they could be interpreted
as a quasi-periodic
oscillation.
Key words: cataclysmic variable stars – recurrent novae – CCD photometry – light curve.
AO SERPENTIS: OBSERVATIONS AND INTERPRETATIONS
PANAGIOTIS ZAVROS, SOTIRIOS TSANTILAS, ELENI ROVITHIS-LIVANIOU
Department
of Astrophysics-Astronomy and
Mechanics, Faculty of Physics,
Panepistimiopolis,
Zografos 157 84, Athens, Greece
E-mail:
elivan@phys.uoa.gr
Abstract. The CCD light
curves of the Algol-type eclipsing binary AO Ser
obtained with the 40-cm Cassegrain telescope at the
Athens University
Observatory in June 2005 are presented, analyzed, and discussed. The
light
curve analysis was made with the
PHOEBE program, based on the Roche geometry.
Moreover, as AO Ser belongs to the newly formed class of oEA stars, the
oscillating frequencies of its primary component were calculated. This
was
achieved with the Period04 program, and it was found
that it has multi-periodic
behavior.
Key words: astrophysics – variable stars – eclipsing binaries – light curve analysis – asteroseismology.
NEW SPECTROSCOPIC RESULTS FOR
THE ECLIPSING BINARY
HS HER
O. LATKOVIĆ 1, H.
MARKOV 2, I. Vince 1
(1
Abstract.
The detached eclipsing binary HS
Her, with a slightly eccentric orbit and confirmed apsidal motion, has
a rich
history
of photometric observations. However, the only spectroscopic study of
this interesting binary system was carried out by Cesco
and Sahade in 1945;
their spectroscopic elements are still in use.
We
present new spectroscopic measurements of HS Her, obtained in NAO
Rozhen from
2002 to 2007, and make a
comparison of existing spectroscopic elements and our
results.
STUDY
OF ECLIPSING BINARIES
WITH PHOEBE
O. LATKOVIĆ
1, A. PRSA
2, G. MATIJEVIĆ 3
(1 Serbia, 2 USA,
3 Slovenia)
Abstract. PHOEBE (Physics of Eclipsing Binaries) is a next-generation facility for modelling eclipsing binary systems.
Built
on top of the widely used Wilson-Devinney code, PHOEBE supports a large
set of
physical effects that determine the
nature of a binary system: asynchronous
eccentric orbits, gravity darkening and ellipsoidal variations,
reflection
effect, spots, third
light, proximity effects, and so forth. PHOEBE also
features a number of numerical enhancements, like the Nelder and Mead’s
Simplex, Powell’s Direction Set method, and Artificial Neural Networks.
PHOEBE
is also suitable for planetary transit searches and identification of
the false
positives, while its powerful scripting
language makes it ready for fully
automatic pipeline reduction of data from large-scale surveys.
Here we present the newest version of PHOEBE,
with examples of its major capabilities and an outlook of the future
development.
SEASONAL
LIGHT VARIATIONS OF
THE CONTACT SYSTEM
V839 OPH IN
2007
A. LIAKOS, G.-P. GRADOULA, P. NIARCHOS
(
Abstract. New CCD BVRI light curves of the
The within-season changes in the light
curves over monthly, weekly, and even daily time scales are presented
and
possible
mechanisms for such variations are discussed.
POSSIBLE
ACCRETION DISK
IN THE
ACTIVE BINARY SYSTEM
V455 CYGNI
G. DjuraŠEVIĆ 1, I. Vince
1, I. Antokhin
2,
M. Zakirov 3, M. Eshankulova 3
(1
Abstract. The present study is devoted to the
problem of the estimation of orbital and physical parameters for the
early
EB-type
massive eclipsing binary V455 Cyg. The estimation is based on the
interpretation of the new photometric UBVR observations
obtained at the
Maidanak Observatory during 2000–2002, and on the radial velocity study
based
on the spectroscopic data
obtained at the 1.25-m telescope of the Crimean
Observatory of the Sternberg Astronomical Institute in September 2004.
The
light curves and radial velocity curves are analyzed within the
framework of
two different Roche models.
The
analysis shows that, with spectroscopically estimated mass-ratio q = m1/m2
= 1.343, the seasonal UBVR
light curves
(2000–2001 and 2002) can be fitted by two different Roche models.
The first one is a slight over-contact model (f =
3–12%),
and the second one is the model with an accretion disk
surrounding the components capturing the matter flowing from the
Roche-lobe-filling component.
For a
successful explanation of the seasonal light-curve changes (especially
in
amplitude), the over-contact model requires
slight change in over-contact
degree and change of the orbit inclination, which is the consequence of
the
precession of the orbital
plane of the eclipse system in the gravitational
field of the distant third component. However, the most natural
explanation of
its
photometric and spectroscopic behaviour can be found by using the model
with an accretion disk, which suggests a strong and
variable mass transfer from
the less massive Roche-lobe-filling component to accretor. There also
exists a
possibility that part of
the transferred matter escapes into the surrounding
space forming an inhomogeneous and nonstationary circumstellar envelope.
Smaller
deformations and a slight asymmetry of the unstationary light curves
support
also the existence of such an envelope,
since they can be caused by the
modulation of the radiation of the components while passing through
this
envelope. The measured
radiate polarisation of this system speaks also in
favour of the hypothesis about the existence of a circumstellar
envelope.
PHASE-SPACE STRUCTURE IN LENNARD-JONES-TYPE PROBLEMS
VASILE MIOC 1, EMIL
POPESCU 2,
NEDELIA ANTONIA
POPESCU 1
1 Astronomical
Institute of the
Str.
Cuţitul de
Argint 5, 040557 Bucharest, Romania
E-mail:
vmioc@aira.astro.ro,
nedelia@aira.astro.ro
2 Technical University of Civil Engineering
Bd.
Lacul Tei 124, 020396
E-mail:
epopescu@utcb.ro
Abstract.
We consider the
astronomical connotations of the famous Lennard-Jones potential. To
study the
two-body problem
associated to this potential, we use McGehee’s regularizing
transformations. We investigate all possible situations by making vary
the
angular momentum constant in the three cases: negative, zero, and
positive
energy. We obtain the global flow, exhibiting a great
variety of orbits, a
homoclinic one included. The results of the qualitative analysis are
strongly
supported by numerical endeavours,
which point out and prove all features found
via qualitative methods. All phase portraits are interpreted in terms
of
physical trajectories.
Key words: celestial mechanics – two-body problem – Lennard-Jones potential – qualitative analysis – numerical simulation.
PRELIMINARY ORBIT DETERMINATION WITH TOPOCENTRIC CORRECTION
ZORAN KNEŽEVIć
Astronomical
Observatory
Volgina
7,
11160 Belgrade, Serbia
E-mail:
zoran@aob.bg.ac.yu
Abstract. The classical
theory of preliminary orbit algorithms is not
suitable under the conditions of the next generation surveys, with
much larger
number density of observed objects. It is found to be incomplete in
that the
consequences of the topocentric correction
had not been fully studied. We show
that it is possible to rigorously account for the topocentric
correction,
possibly at the price of an
increase in the number of alternate preliminary
orbit solutions, but without impairing the overall orbit determination
performance.
Key words: celestial mechanics – asteroids – preliminary orbits.
INVESTIGATION OF ASTEROID DYNAMICS VIA NUMERICAL METHODS
CĂTĂLIN GALEŞ 1, CIPRIAN CHIRUŢĂ 2
1 Faculty
of Mathematics,
Blvd. Carol I 11, 700706 Iaşi, Romania
E-mail: cgales@uaic.ro
2 “Ion
Ionescu de la Brad”
M. Sadoveanu
alley 3, 700490 Iaşi, Romania,
E-mail:
kyru@univagro-iasi.ro
Abstract. Relatively
recently, a new method, which allows to distinguish between chaotic and
regular
motions, has been introduced.
The fast Lyapunov indicator (FLI) has turned out
to be also sensitive to regular motions. FLI can be used not only to
discriminate
between regular and chaotic motions, but also to differentiate
resonant, nonresonant and periodic orbits among the regular ones.
These results
have been obtained in the context of symplectic mappings and in
particular on
the standard map, and then recovered
in 2D continuous dynamical systems by
introducing a new quantity: the orthogonal FLI (OFLI). The OFLI has
been used
for the
Hénon and Heiles system and for the restricted three-body
problem with
equal masses of the primaries. We deal with the latter problem,
but for various
masses of primaries. We compute the OFLI values on a given grid of
initial
conditions and investigate the dependence
of the regular sets and chaotic
regions on the primaries masses. In particular, the Sun-Jupiter case is
considered, and the motions of
some asteroids are discussed.
Key words: Restricted three-body problem – orthogonal fast Lyapunov indicator – regular and chaotic orbits.
PHOTOGRAVITATIONAL
ELLIPTIC RESTRICTED
THREE-BODY PROBLEM: CONSTANTIN
POPOVICI’S MODEL
Ciprian
Chiruta
“Ion
Ionescu de la Brad”
Al.
M.
Sadoveanu 3, 700490, Iaşi, Romania
E-mail:
kyru@univagro-iasi.ro
Abstract. We present the
model of the photogravitational field proposed by
the Romanian mathematician and astronomer
Constantin Popovici. The elliptic
case of the photogravitational restricted three-body problem is
studied, as
well as its equilibrium
points. Starting from the vector equation of motion,
without distinguishing between the elliptic and the circular motion, we
discuss
separately the two cases, emphasizing the differences as they appear.
The
application concerns the analysis of the ratio between
the radiative and
gravitational forces acting upon the test particle, integrating the
motion equations
with respect to the true anomaly.
Key words:
celestial mechanics – restricted three-body problem –
photogravitational
field – equilibria.
CLASSICAL POST-NEWTONIAN APPROXIMATION FOR FOCK’S PROBLEM
VASILE URECHE 1, RODICA ROMAN 2, VASILE MIOC 3
1 “Babeş-Bolyai” University, Faculty of Mathematics and Computer Science
Str.
M.
Kogălniceanu 1, 400084 Cluj-Napoca, Romania
E-mail:
vureche@math.ubbcluj.ro
2 Astronomical
Institute of the
Astronomical
Observatory Cluj-Napoca
Str.
Cireşilor
19, 400487 Cluj-Napoca, Romania
E-mail:
rdcroman@yahoo.com
3 Astronomical
Institute of the
Str.
Cuţitul de
Argint 5, 040557 Bucharest, Romania
E-mail:
vmioc@aira.astro.ro
Abstract. For the two-body
problem in Fock’s relativistic gravitational
field, we consider a first-order approximation in 1/c2.
For a negative-energy constant, the solution is a
precessional ellipse. We compute the pericentre advance, and compare it
with
Einstein’s result for a weak gravitational field.
Key words: celestial mechanics – post-Newtonian approximations – Fock’s field. – pericentre advance.
ON
THE REGIONS OF
POSSIBLE MOTION IN
THE PLANAR THREE-BODY
PROBLEM
M. BARBOSU
(
Abstract.
Our work concerns the planar
three-body problem. For fixed values of the constants of energy and
angular
momentum, one can get inequalities that determine the regions where the
motion
can occur. In this paper we prove a new
inequality that generalizes previous
results and provides new qualitative results.
INVESTIGATION OF A POLAR FILAMENT ERUPTION IN STAGES
Cristiana Dumitrache,
Iulia Chifu, Marilena
Mierla
Astronomical
Institute of the
Str.
Cuţitul de Argint 5, 040557
E-mail:
crisd@aira.astro.ro
Abstract. A huge polar filament
erupted on
dynamics of this filament in order to detect the
mechanism that produced its destabilization. The filament erupted in
several
phases.
Few active regions were observed at the South end of the filament. We
study the extrapolated 3D coronal magnetic field evolution
of zone, in order to
understand the influences of these active regions on the filament
dynamics. We also focus on the
CMEs evolution
from the solar disk to the interplanetary space.
Key words: Sun – filaments – CME – data analysis.
ARTEMIS,
A
SOLAR RADIOSPECTROGRAPH
C. Caroubalos 1, X. MOUSSAS
1, P. PREKA-PAPADEMA
1, A. HILLARIS 1,
A. KONTOGEORGOS
1, C. E. ALISSANDRAKIS
1, J.-l. BOUGERET
2,
G. DUMAS 2
(1
Abstract. We
present the solar
radiospectrograph of the
since 1996.
Observations now cover the whole frequency range from 20 to 650 MHz.
The
spectrograph has the old 7-meter
moving parabolic antenna for 110 to 650 MHz
and a new stationary antenna for the 20 to 110 MHz. There are two
receivers
operating in parallel, one sweep frequency for the whole range (10
spectra/sec,
630 channels/spectrum) and one acousto-optical
receiver for the range 270 to
470 MHz (100 spectra/sec, 128 channels/spectrum). The data acquisition
system
consists of two
PCs (equipped with 12 bit, 225 ksamples/sec DAC, one for every
receiver) Windows operating system, connected through
Ethernet. The daily
operation is fully automated: pointing the antenna to the Sun, starting
and
stopping the observations at preset
times, data acquisition, and archiving on
DVD. We can also control the whole system through modem or
Internet. The instrument
can be used either by itself to study
the onset and evolution of solar radio bursts, or in conjunction with
other
instruments, including
the Nancy Decametric Array, the WIND/WAVES, and the new
spacecraft STEREO/WAVES low frequency receivers to study
associate
interplanetary phenomena.
ASTEROID
LIGHTCURVE PHOTOMETRY
FROM
NAO ROZHEN –
DECEMBER 2006 TO
AUGUST 2007
V. IVANOVA 1, A.
KRYSZCZYNSKA 2, G. APOSTOLOVSKA
3
(1 Bulgaria, 2 Poland, 3 FYROM)
Abstract. We present CCD
photometric observations of selected asteroids performed at Rozhen
National
Astronomical Observatory,
Bulgaria
telescope equipped with an ST-8E CCD
camera. The lightcurves obtained at different observing geometry are
necessary
for asteroid
poles and shapes determination.
PHOTOMETRIC
AND MORPHOLOGICAL
PROPERTIES OF
GALAXY PAIRS IN
THE ENVIRONMENT
OF
RADIO GALAXIES
NEDELIA ANTONIA
POPESCU
Astronomical
Institute of the
Str.
Cuţitul de
Argint 5, 040557 Bucharest, Romania
E-mail:
nedelia@aira.astro.ro
Abstract. Inside dense
environments of AGNs, galaxy-galaxy interactions and
galaxy collisions, which sometimes lead to final merging,
can produce strong
modification of galaxies morphologies and even develop complex
structures. A
detailed analysis of photometric and
morphological properties of galaxies in
pairs and groups in the field of radio galaxy 3C 220.1 (z
= 0.62) is performed, using combined
optical-NIR photometric
data, HST/WFPC2 morphological data, and HST/WFPC2 archival images.
Key words: extragalactic astronomy – AGNs’ environment – galaxy interactions – galaxy pairs.
Stellar density distribution of
the SMALL
MAGELLANIC CLOUD in the near
infrared
EVDOKIA LIVANOU 1, Mary kontizas 1, evangelos kontizas 2,
ioannis gonidakis 1, Uli klein 3
1 Department
of Astrophysics-Astronomy and Mechanics, Faculty of
Physics,
Panepistimiopolis,
Zografos 157 84, Athens, Greece
E-mails:
elivanou@phys.uoa.gr,
mkontiza@phys.uoa.gr, jgonidakis@phys.uoa.gr
2 Institute
for Astronomy and Astrophysics, National
Observatory of
E-mail:
ekonti@astro.noa.gr
3 Radioastronomisches
Institut der Universität Bonn
Auf dem Hugel 71, D-53121 Bonn,
Germany
E-mail:
uklein@astro.uni-bonn.de
Abstract. The stellar
populations of the Small Magellanic Cloud (SMC) are
investigated in order to determine their density distribution.
Surveys such as 2MASS and DENIS are ideal for
the investigation of the spatial distribution of the stellar population
in
nearby galaxies.
Data in the near infrared allow us to access late-type stars
that are marginally covered by optical observations, as well as younger
stars.
Star counts and the corresponding isopleths in both surveys of distinct
stellar
types such as the intermediate (C stars) and older populations
in the SMC
reveal an exponential disk structure, where the scale heights are
calculated
from data of both surveys.
Key words: SMC – scale height.
SEMI-ANALYTICAL APPROXIMATIONS OF THE FORMATION OF DARK MATTER HALOES IN A ΛCDM UNIVERSE
NIKOS HIOTELIS
First
Experimental Lyceum of
Ipitou
15,
Plaka, 10557, Athens, Greece
E-mail:
hiotelis@ipta.demokritos.gr
Abstract. In this paper we
are using the so-called merger trees for the
purpose of investigating the formation of dark matter haloes.
We use the model
of a ΛCDM Universe. Results concerning the mass growth history, the
density
profiles, and the distribution of their
angular momentum are presented.
Key words: cosmology – dark matter – galaxy formation.
SCIENCE PROJECTS WITH THE ARMENIAN VIRTUAL OBSERVATORY (ArVO)
AREG MICKAELIAN 1, LUSINE Sargsyan 1, KAMO Gigoyan 1, LIDIA Erastova 1, PARANDZEM Sinamyan 1, LILIT Hovhannisyan 1,
ENRICO Massaro
2, ROBERTO
Nesci 2, CORINNE Rossi 2, SILVIA
Gaudenzi2, SILVIA Sclavi2,
GIUSEPPE CIRIMELE 3,
DANIEL Weedman 4, JAMES Houck 4, DON Barry 4,
ALAIN SARKISSIAN 5,
WILLIAM Thuillot 6, JÉRÔME Berthier 6,
PHILIPPE Prugniel 7,
IA Kochiashvili 8,
GOR Mikayelyan
9
1 Byurakan Astrophysical Observatory (BAO)
Byurakan
378433, Aragatzotn province,
E-mails:
aregmick@apaven.am,
sarl@bao.sci.am, kgigoyan@bao.sci.am, ke@bao.sci.am,
sinam@bao.sci.am, lilit@bao.sci.am
2 Università degli Studi di Roma “La
Sapienza”
Piazzale
Aldo
Moro 5, 00185 Rome, Italy
E-mails:
Enrico.Massaro@uniroma1.it, Roberto.Nesci@uniroma1.it,
Corinne.Rossi@uniroma1.it, Silvia.Gaudenzi@roma1.infn.it,
Silvia.Sclavi@istruzione.it
3 M.I.G.G., s.r.l.
Via Pertini 61, 87030 Rende, Italy
E-mail: cirimele@migginformatica.com
4 Cornell University
220 Space Sciences Building,
E-mails: dweedman@isc.astro.cornell.edu,
jrh13@cornell.edu,
don@astro.cornell.edu
5 Institut
“Pierre Simon Laplace”, Service d’Aéronomie
Route des Gatines BP3, F-91731
Verrières-le-Buisson, France
E-mail: Alain.Sarkissian@aerov.jussieu.fr
6 Institut
de Mécanique Céleste et de Calcul des
Ephémérides, Observatoire de Paris
77 av. Denfert Rochereau, Bat. A, F-75014
Paris, France
E-mails: William.Thuillot@imcce.fr,
Jerome.Berthier@imcce.fr
7 Université
Lyon 1, Observatoire de Lyon
F-69230 St. Genis Laval, France
E-mail: prugniel@obs,univ-lyon1.fr
8
E-mail: ia_ko17@yahoo.com
9
1 Alex Manoogian,
Abstract. The main goal of
the Armenian Virtual Observatory (ArVO) is to
develop efficient methods for science projects based
on the digitized famous
Markarian survey (Digitized First Byurakan Survey, DFBS) and other
large
astronomical databases, both
Armenian and international. Two groups of projects
are especially productive: search for new interesting objects of
definite types
by low-dispersion template spectra, and optical identifications of new
gamma,
X-ray, IR and radio sources. The first one is based
on modeling of spectra for
a number of types of objects: QSOs, Seyfert galaxies, white dwarfs,
subdwarfs,
cataclysmic variables,
planetary nebulae, C stars, etc. Each kind of object
appears in the DFBS with its typical SED and spectral lines (for
objects having
broad lines only). The search criteria define how many objects will be
found
for further study, and may restrict these numbers leaving
with the best
candidates. At present, a number of science projects of search for new
objects
have been started: search for blue stellar
objects, search for extremely red
objects, search for variable objects, etc. Optical identifications have
been
proven to be rather efficient
for IR sources from IRAS PSC and FSC. Tests have
been carried out for X-ray and radio sources, as well.
Key words: virtual observatories – surveys – databases – QSOs – white dwarfs – cataclysmic variables – carbon stars – asteroids – optical identification.
ASTRONOMY
IN
KATRIEN KOLENBERG 1,2
1.Institut
für Astronomie, University of
Vienna
Türkenschanzstrasse
17, A-1180 Vienna, Austria
E-mail:
kolenberg@astro.univie.ac
2
Instituut voor
Sterrenkunde
Celestijnenlaan
200D, B-3001
Abstract. The aim of this
note is to make the community aware of the
astronomical potential of
the Astronomical Observatory of Mongolia is presented. The blue
skies after which the country was named, the
increasingly high level of
education and motivation among its young inhabitants, plus the fact
that there
are few observatories
in
astronomy in
Key
words: astronomy education – sites –
DID
THE ANCIENTS KNOW
PETROS ROVITHIS1, ELENI
ROVITHIS-LIVANIOU2,
MAGDA STAVINSCHI3
1 Institute of Astronomy and Astrophysics
2 Department
of Astrophysics-Astronomy and Mechanics, Faculty of
Physics,
Panepistimiopolis,
Zografos 157 84, Athens, Greece
E-mail:
elivan@phys.uoa.gr
3 Astronomical
Institute of the
Str.
Cuţitul de
Argint 5, 040557 Bucharest, Romania
E-mail:
magda@aira.astro.ro
Abstract. In this paper the
most important arguments, being either against
or in favour of the subject of
whether the ancients knew and had travelled to it are referred.
Especially those reported by Notaras in his book
Introduction to the Spherical and Geographical, published in
Key words: the lost Atlantis island – ancient Greeks – myths – big travels.
ROMANIAN
MODERN ASTRONOMY
AT
CENTENARY
M. STAVINSCHI, V.
MIOC
(Romania)
Abstract. By
chance, the Romanian Year of Astronomy (2008, the centenary of the
Bucharest
Observatory of the
Astronomical Institute of Romanian Academy) is preceded and
followed by two important international events:
IHY (2007) and IYA (2009). So,
our actions as to capitalization of astronomical heritage, knowledge of
astronomy
home and abroad, education of the young generation, are more and more
intense.
In this contribution, we remember some
remarkable moments of the Romanian astronomy along the last 100 years.
We
especially intend to present some ways in which this exceptional
triennium for
astronomy will be celebrated.
THE
ANTIKYTHERA MECHANISM, THE
OLDEST KNOWN ASTRONOMICAL
COMPUTER
X. MOUSSAS 1, J. H.
SEIRADAKIS 1, T. FREETH
2, Y. BITSAKIS
1,
A. tsELIKAS 1, E.
MAGKOU 1, M. ZAFEIROPOULOU 1,
R.
HADLAND 2,
A. RAMSEY 2, M. ALLEN
2, T. MALZBENDER 3, M.
G. EDMUNDS
2
G. DUMAS 2
(1
Abstract. An
extraordinary mechanism was
found by sponge divers at the bottom of the sea near the
Greece
complex than any known astrolabe. The
instrument has been studied by Rediadis (1902), Theofanidis (1932),
Price
(1959, 1975),
Wright (1995, 2002) and it was known to be a complex astronomical
calculator. We have performed a new study of this miraculous
Mechanism using
modern non-linear high-resolution computer tomography of X-tek Systems
and
Polynomial Texture Map
(PTM) 3D surface photography by HP. These techniques
enabled us to have very detailed representations of the interior of the
Mechanism, to read
the computer manual, that has been
hidden for over 21 centuries in the rust, to reconstruct and understand
better
the Antikythera Mechanism. The manual has a mechanical section, an
astronomical, some geographical notes (the name
ISPANIA (
of a planet appears several
times. There are several dials and scales, two of them spiral, one for
the
Saros and Exeligmos cycle
(18 years plus 8 hours and 54 years and one day for
the eclipses of the Sun and the Moon, with inscriptions of the eclipses
on the
scale, a second spiral scale for the Meton’s cycle (19 years) and
Callippic
cycle (76 years) for an accurate calendar.
The
Moon mechanism shows the position and the phase of the Moon during the
month.
The velocity of the Moon is variable
following Hipparchus’ theory, which
constitutes a good approximation of Kepler’s second law for the angular
velocity, i.e., the
Moon goes faster near the perigee and slower at the apogee.
The study continues and we have new results almost continuously.