THE INTERNATIONAL HELIOPHYSICAL YEAR
Joseph M. Davila,
Nat Gopalswamy,
Barbara
J. Thompson
Greenbelt,
MD 20771,
USA
E-mails:
davila@stars.gsfc.nasa.gov, gopals(@)fugee.gsfc.nasa.gov, barbara.j.thompson@nasa.gov
Abstract. On
beginning of the space age; as mankind took the first steps to leaving
the
protected environment of Earth’s atmosphere.
Discovery of the radiation belts,
the solar wind, and the nature of Earth’s magnetosphere prepared the
way for
the
inevitable human exploration to follow. Soon, Cosmonauts and Astronauts
orbited Earth, and then in 1969, Astronauts
landed on the Moon. Today a similar
story is unfolding, the spacecraft Voyager has crossed the termination
shock, and
will soon leave the heliosphere. For the first time, man will begin to
explore
the local interstellar medium. It is inevitable
that, during the next 50 years,
exploration of the solar system including the Moon, Mars and the outer
planets
will be the
focus of the space program, and, like 50 years ago, unmanned probes
will lead the way, followed by human exploration.
Key words: solar physics – heliosphere – International Heliophysical Year.
GALAXY PAIRS AND STAR FORMATION ACTIVITY IN HICKSON COMPACT GROUPS
IBRAHIM SELIM, GAMAL BAKR ALI, HAMED ISMAIL, AHMED ESSAM,
ALI HAROON, MOHAMED ABDEL-SABOUR
National Research Institute of Astronomy and Geophysics (NRIAG)
11421-Helwan,
Cairo, Egypt
E-mail:
selim@nriag.sci.eg
Abstract. We investigate
the effect of galaxy interaction on star formation
in dense environment through the far-infrared
emission (FIR) of galaxies using
data of Hickson Compact Groups (HCGs). We identified 470 galaxy pairs
with cr
(proximity criterion) ≤ 390, and 358
galaxy pairs with rp
(projected separation) less than 100 kpc and difference in velocity
DV ≤
350 km/s. We identified 41 close galaxy pairs with rp less than 25 kpc and DV ≤ 100 km/s. The star
formation rate
(SFR) of galaxies in galaxy
pairs is found to be enhanced for close galaxy pairs. The large
fraction of
star formation activity is
probably due to the activity in the exchange of
matter between the companions. We established the catalogue of galaxy
pairs
in
HCGs.
Key words: extragalactic astronomy – galaxy pairs – Hickson compact groups.
ON THE DETECTION AND DIAGNOSIS OF LOW-LEVEL STELLAR VARIABILITY
ALEXANDRU POP
Astronomical
Institute of the
Astronomical
Observatory Cluj-Napoca
Str.
Cireşilor
19, 400487 Cluj-Napoca, Romania
E-mail:
apop@academie.cj.edu.ro
Abstract. The problem of
detection and diagnosis of stellar variability
phenomena is approached via the method proposed
by Pop (2005) and derived from
that of Kuschnig et al. (1997). The numerical experiments performed by
us prove
its ability
to detect low-amplitude periodic signals in the presence of
Gaussian and AR1 noise as well as the
presence of the high-noise
level.
Key words: astrophysics − stellar variability – data analysis.
ON THE LIGHT-CURVE SHAPE OF DL CAS
ALEXANDRU POP
Astronomical
Institute of the
Astronomical
Observatory Cluj-Napoca
Str.
Cireşilor
19, RO-400487 Cluj-Napoca, Romania
E-mail:
apop@academie.cj.edu.ro
Abstract. The study of the
temporal behavior of DL Cassiopeiae light curve
shape is resumed. The present approach is based
on the use of the previously
introduced structural parameters (Pop and Roman 2006) through the
relative
length of given light
curve branches, or relative surface areas delimited by
the light curve and well-defined magnitude levels. The variability
survey
was
performed using two methods based on numerical simulations. In spite of
the
overall conclusion concerning the light curve
stability, the hypothesis of the
presence of some low level, time-dependent, distortions of the light
curve
profile, both in minimum
and maximum light, may be taken into account.
Unfortunately, at this moment the pathological effects of poor phase
coverage
and
of the too long time-base of some existing data sets cannot be
surpassed.
That is why, new high-quality photometric observations,
with good phase
coverage, are needed in order to understand the temporal behavior of DL
Cas
light curve.
Key words: variable stars – δ Cephei stars – light-curve shape variability.
THE LENNARD-JONES-TYPE TWO-BODY PROBLEM. I. COLLISION AND ESCAPE DYNAMICS
VASILE MIOC
Astronomical
Institute of the
Str.
Cuţitul de
Argint 5, 040557 Bucharest, Romania
E-mail:
vmioc@aira.astro.ro
Abstract. We extend the
famous Lennard-Jones potential (characteristic to
molecular dynamics) to the astronomical framework.
We tackle the two-body
problem only via qualitative, geometrical methods of the theory of
dynamical
systems. Here we approach
two limit situations: collision and escape,
describing the dynamics in their neighbourhood. This is only the first
step in
understanding
this problem from a qualitative standpoint.
Key words: celestial mechanics two-body problem − Lennard-Jones potential − collision − escape.
VENUS’ TRANSIT 2004: OBSERVATIONS AND ANALYSIS OF THE BLACK-DROP EFFECT
ADRIAN
SABIN POPESCU 1,
MIRCEA
RUSU 2
1 Astronomical
Institute of
the
Str.
Cuţitul de
Argint 5, 040557 Bucharest, Romania
E-mail:
sabinp@aira.astro.ro
2 University
of
Str.
Atomiştilor 1,
CP MG-11, 077125 Bucharest-Măgurele, Romania
E-mail:
mvrusu@yahoo.com
Abstract. The
transit of Venus across
the solar disk took place on
TRACE satellite images, we determine the moment (before the third
contact) at which the black-drop effect occurred.
Key words: Venus’ transit − black-drop effect − image analysis − fractal dimension.