THE
30-31 August 2004,
The Third
Annual Meeting of the Armenian Astronomical Society was held on August 30-31,
2004, in the Byurakan Astrophysical Observatory Conference Hall, where a number
of outstanding meetings had been organized, including 4 IAU Symposia and 1 IAU
Colloquium. It was organized jointly by the Armenian Astronomical Society and
the Byurakan Astrophysical Observatory. The organizing committee consisted of
H.Harutyunian, T.Magakian, A.Mickaelian, T.Movsessian, and E.Nikoghossian.
Some 50 astronomers
participated in the Meeting, including scientists from the USA (J.Mather), Germany (F.Aharonian, T.Arshakian, V.Hambaryan), Spain
(V.Tamazian), Jordan (R.Kandalyan),
Yerevan State University (A.Sadoyan, K.Shahabasian), Yerevan Physics Institute (V.Gurzadyan), Institute of History of NAS RA (K.Tokhatyan, G.Vardanyan), and
some 35 scientists from the Byurakan Observatory, as well as a number of
students.
The meeting
was opened with a welcome address by Haik Harutyunian,
22 scientific talks by 21 speakers
were given, covering various aspects of astronomy. In addition to the talks on
modern astronomical results, it is worth mentioning talks on archaeoastronomy
in
The Meeting
was sponsored
by Mr. David Nelson (
Abstracts of the
talks
ON ANCIENT ASTRONOMY IN
E.S. PARSAMIAN
Byurakan Astrophysical Observatory (BAO),
The
Armenian highland is one of the ancient cradles of civilization. Many
investigators of the history of astronomy, having no facts to hand, came to
conclusions that the ancient inhabitants of
The
most important discovery, which enriched our knowledge of ancient astronomy in
On
the bank of the river Metzamor, some 30 km west of
It
was shown that in the years between 2800-2600 B. C. Sirius could have been
observed at Solstice in the morning, in the rays of the rising Sun, this being
so-called helical rising of Sirius. It is obvious from the data that Sirius,
the brightest star in the hemisphere could have been the object of worship by
the inhabitants of Metzamor. It is possible that, like the ancient Egyptians,
the inhabitant of Metzamor related the first appearance of Sirius with the
opening of the year.
Among
the ancient monuments in
The
diameter of the main stone ring of Zorats Kar is more than 30m and it is notable that on some stones
found in the eastern part there are well polished round holes, which could have
been used for the observation of the Sun in the days of equinox and solstice.
Main ring is connected with megaliths in S-E direction by gate of two megaliths
the distance between which more than between other stones. The middle line of
gate has direction East-West.
JAMES WEBB SPACE TELESCOPE
John MATHER
Space Telescope Science Institute (STScI),
A
review on the project of the James Webb Space Telescope (JWST, formerly New
Generation Space Telescope, NGST) was given.
GRAVITATIONAL WAVES FROM NEUTRON STARS AND WHITE
DWARFS
D.M. Sedrakian, A.A. SADOYAN, K.M. Shahabasyan,
M.V. Hayrapetyan
We
will go through present stage of Gravitational Wave observatories and summarize
main results of collaboration between Montana State University Billings and
Rotating
white dwarfs undergoing quasi-radial oscillations can emit gravitational
radiation in a frequency range from 0.1-0.3 Hz. Assuming that the energy source
for the gravitational radiation comes from the oblateness
of the white dwarf induced by the rotation, the strain amplitude is found to be
10-25 for a white dwarf at ~50pc. We had calculated thermal energy
loses through magneto-hydrodynamic mechanism during self similar oscillations
to compare with energies emitted in GW band. We examine also possibility of
gravitational radiation from white dwarfs undergoing self-similar oscillations
which are fed by the energy of the differential rotation of the white dwarf. We
consider two cases of angular momentum distribution. Assuming the energy of the
self-similar oscillations causing gravitational wave emission is about 10% of
the energy dissipated in the differentially rotating white dwarf, the strain
amplitudes are again found to be less than 10-25 for a white dwarf
at ~ 50pc. Nearby oscillating white dwarfs may provide a clear enough signal to
investigate white dwarf interiors through gravitational wave astroseismology.
Undamped
quasi-radial oscillations rotating neutron stars and the gravitation radiation
generated by them are discussed. Two possible sources of energy for maintaining
these oscillations are mentioned: the energy of deformation of the decelerating
neutron star (spin down) and the energy released during a jump in the star’s
angular velocity (glitch). Expressions are derived for the intensity of the
gravitational radiation and the amplitude of a plane gravitational wave for an
earthbound observer. Estimates of these quantities are obtained for the Vela
and Crab pulsars, for which the secular variation in the angular velocity is
most often accompanied by irregular variations. It is shown that gravitational
waves from these pulsars could be detected by the new generation of detectors.
THE INNER STRUCTURE OF STELLAR OUTFLOWS
T.A. MOVSESSIAN1, T.Yu.
Magakian1, A.V. Moiseev2, M. Smith3
1- Byurakan Astrophysical Observatory (BAO),
2 – Special Astrophysical Observatory (SAO),
3 – Astronomical Observatory
We
present new imagery and Fabry-Perot scanning
interferometry of Herbig-Haro jets and associated cometary reflection nebulae. Observations
are carried out on 2.6m (
RADIO OUTFLOWS FROM SEVERAL NEW SOUTHERN OBJECTS
A.L. GYULBUDAGHIAN
Byurakan Astrophysical Observatory (BAO),
The results of radio
observations on SEST telescope (Cerro La Silla,
COOL CARBON STARS IN THE HALO: A NEW SURVEY BASED ON
2MASS
1 –
2 –
3 - Byurakan Astrophysical Observatory (BAO),
4 –Observatoire de Grenoble,
We
present the first results of a new survey for finding cool N –type carbon( C ) stars in the halo of the Galaxy. Candidates were selected in the 2MASS
Second Incremental Release database with JHK, colors typical red AGB C stars
and K < 13, and subsequently checked through medium resolution slit
spectroscopy. We discovered 27 new C stars plus one known previously and two
similar objects in the Fornax and Sculptor dwarf
galaxies. We determine and discuss the properties of our sample, including
optical and near-infrared colors, radial velocities, as well as H(Alpha) emission and variability that are frequent, all
these characteristics being compatible with an AGB C - type classification.
Surprisingly, of the 30 studied objects, 8 were found to have small but
measurable proper motions in the USNO-B1.0 catalogue, ranging over 8 < PM
< 21 mas/yr and opening the possibility that some objects could perhaps be
dwarf carbon stars. Yet, a detailed analysis based on comparison with the sample
of known carbon dwarfs leads us to consider these PM as incompatible with the
broader picture suggested by the other data taken as a whole. So, we adopt the
view that all objects are of AGB type, i. e. luminous
and distant. Because the stream of Sagittarius dwarf galaxy is known to be the
dominant source of luminous C stars in the halo, we chose to determine
distances for our sample by scaling them of the 26 known AGB C stars of the Sgr galaxy itself, which are found to be, in the K band,
near 0.5 mag less luminous than the average LMC C
stars for a given J - K color. The obtained distances of our halo stars range
from 8 to 80 kpc from the Sun. Then, examination of
position and radial velocities shows that about half belong to the Sgr stream. Our findings suggest that numerous AGB C stars
remain to be discovered in the halo. Long term K - band monitoring would be of
great value to ascertain distance estimates through the period-luminosity
relation, because a large fraction of our sample is probably made of Mira
variables.
SEARCH, IDENTIFICATION AND STUDY OF VARIABLE SOURCES
IN X-RAYS
V.V. HAMBARYAN
Astrophysical Institute
I
will present results of ongoing systematic search, identification and study of
variable X-ray sources of galactic and extragalactic origin, using available
large amount of archived data, based on ROSAT, Chandra and XMM-Newton
observations. I will discuss methodical aspects of the problem based on a
Bayesian approach of variability and periodicity search. It will also address
current problems in understanding physical conditions and astrophysics
underlying the mechanisms responsible for the observed variability of stars and
active galactic nuclei. In particular, I will focus on fundamental physical
questions concerning the coronae of normal stars, heating mechanism of them,
the role of flares and microflares of heating. How does it depend on parameters
such as mass, convection, rotation and age?
DSS1/DSS2 Astrometry of FBS
Blue Stellar Objects:
Accurate Positions and Other
Results
A.M. Mickaelian
Byurakan Astrophysical Observatory (BAO),
Accurate
measurements of the positions of 1101 First Byurakan Survey (FBS) blue stellar
objects have been carried out on the DSS1 and DSS2 (red and blue images). To establish
the accuracy of the DSS1 and DSS2, measurements have been made for 153 AGN for
which absolute VLBI coordinates have been published. The rms errors are:
0.45" for DSS1, 0.33" for DSS2 red, and 0.59" for DSS2 blue in
each coordinate, the corresponding total positional errors being 0.64",
0.46", and 0.83", respectively. The highest accuracy (0.42") is
obtained by weighted averaging of the DSS1 and DSS2 red positions. It is shown
that by using all three DSS images accidental errors can be significantly
reduced. The comparison of DSS2 and DSS1 images made it possible to reveal
positional differences and proper motions for 78 objects (for 62 of these for
the first time), including new high-probability candidate white dwarfs, to find
objects showing strong variability (high-probability candidate cataclysmic
variables), and objects having images showing slight extension in DSS2 red and
IR (candidate QSOs and AGN).
The Digitized First Byurakan
Survey (DFBS)
A.M. Mickaelian1,
L.R. Hovhannisyan1, R. Nesci2, S.
Gaudenzi2, E. Massaro2, C. Rossi2, S. Sclavi2,
D. Trevese2,
D. Weedman3, J. Houck3, D. Barry3,
B. Brandl3, H. Hagen4
1 – Byurakan Astrophysical Observatory (BAO), Armenia
2 – Universita di Roma “La Sapienza”, Italy
3 –
4 – Hamburger Sternwarte
(HS),
The
First Byurakan Survey (FBS) is the largest spectral survey in the Northern sky
covering 17,000 sq. deg at high galactic latitudes. 1500 Markarian galaxies,
thousands of blue stellar objects and late-type stars have been discovered and
optical identifications of 1600 IRAS sources have been made using this
observational material. Some 20,000,000 spectra are present in FBS giving a key
to understanding of the nature of these objects. The project of digitization of
FBS is active since 2002 in frame of an international collaboration between the
Byurakan Observatory (Armenia), Cornell University (USA) and Universita di Roma "La Sapienza" (Italy) and has brought to
creation of a unique database: the Digitized First Byurakan Survey (DFBS).
Beside the scanning and archiving, plate solution, extraction software,
wavelength and flux calibration, templates for different types of objects, a
numerical classification scheme, a catalog of spectra, user interface and DFBS
web page are being made. At present all FBS plates have been scanned and
reduction software is being created and applied. The DFBS database will be open
at the end of 2004. An automatic selection of different types of interesting
objects will be possible and searches for new bright QSOs, faint Markarian
galaxies, white dwarfs, cataclysmic variables, carbon stars, as well as optical
identifications of radio, IR and X-ray sources will be undertaken.
The Hamburg/ROSAT-FSC
Catalogue of Optical Identifications
A.M. Mickaelian1, L.R. Hovhannisyan1,
D. Engels2, H. Hagen2, D.
Reimers2,
1 – Byurakan Astrophysical Observatory (BAO),
2 – Hamburger Sternwarte
(HS),
3 – Max-Planck Institut fuer Extraterrestrische Physik (MPE), Munchen,
The
Hamburg/ROSAT-FSC Catalogue (HRFC) of optical identifications of X-ray sources
is presented. The HRFC includes all 2791 sources from the ROSAT-FSC with
|b|>30, DEC>0, and ROSAT countrate CR>0.04. For the optical
identifications, we have used the Hamburg Quasar Survey (HQS) digitized
spectroscopic plates, DSS1 and DSS2 (blue, red, and IR) images, MAPS
photometric data, USNO-B2.0 (for proper motions), NVSS/FIRST radio and IRAS/2MASS
infrared catalogs, and other available data from the existing catalogs. From
the DSS images we have obtained positional, brightness, color, extension,
variability, PM information, and have given the morphological classification,
have measured the optical-to-X-ray distance. SIMBAD and NED data for known
(bright) objects have been taken. Cross-correlations have been made with the
AGN, WD and CV catalogs (322/8/7 associations, respectively). Using a refined
and improved technology compared to the HRC (Zickgraf et al. 2003), we managed
to identify 97% of sources (2696 sources), compared to 82% in HRC. 2696 sources
are identified with 3187 objects, including 2263 with a single object; other
144 have identification with double or multiple object;
thus we are left with only 289 ambiguous identifications. In addition we have
found 79 by-product objects near the X-ray positions, mainly new faint QSOs.
QSOs and AGN represent the largest group of X-ray counterparts (52.3%), bright
stars (including late type stars, but excluding WDs and CVs) are counterparts
for 34.1% of sources, and the bright galaxies and groups of galaxies comprise
only 5.3% and 4.1%, respectively. We have found a number of interacting/merging
galaxies being counterparts for X-ray sources (2.8%), as well as 1.2% WDs and
0.1% CVs. One of the striking results of this program is the presence of a
large number of binary QSO candidates among the sample of QSOs. The HRFC may be
used for selection and studies of complete samples of various classes of X-ray
emitters.
ON A NEW PECULIARITY OF SPACE DISTRIBUTION OF FLARE
STARS IN PLEIADES CLUSTER
H.S. Chavushian, H.V. Pikichian, A.V. OSKANIAN, G.H. Broutian
Byurakan Astrophysical Observatory (BAO),
As
we know, in the case of spherical symmetry it is possible to restore by the
method of Zeipel [1] the density of the
three-dimensional distribution of stars by means of the distribution of
two-dimensional (surface) density of stars in "reach" clusters. In
the case of poor sample of stars (as, for example, in open clusters) it is more
effective to use the one-dimensional distribution function suggested by Plummer
[2] which is the projection of observed
two-dimensional distribution of stars on an arbitrary axis passing through the
center of the cluster. Making use of the fact that the direction of the
projection axis is arbitrary M. Mnatsakanian [3] succeeded to improve the
process of construction of one-dimensional projection of star distribution by
means of analytic averaging of all the values of azimuths of direction of
projection axis. It became possible to investigate more poor samples such as
the partial density of flare stars in Pleiades. It was shown [4] that there is
region of absence of flare stars – a “hole” in the centre of the cluster.
Afterwards it came out that the existence of this “hole” was conditioned by
existence of bright stars and diffuse matter in the centre of the cluster that
results in observational selection of discovering of stellar flares. The “hole”
was filled gradually with the growth of the quantity of flare stars at the
expense of newly discovered flare stars [5]. An investigation based on a more
complete observational material [6] showed the existence of a region of flare
star “deficit” in the function of two-dimensional distribution in the middle region of radius of
the cluster 2.8£r£3.5 pc.
The
accuracy of the function built by us by M.Mnatsakanian
method during the process of restoration of three-dimensional density of
Pleiades flare stars was not sufficient (non-physical solution) in the region
of above mentioned deficit. So it became necessary to work up a new – finer
method [7] of construction of one-dimensional projection of star distribution.
It makes possible to us more completely the initial information – the integral
function of flare star distribution. The new equation of Abel’s class obtained
and solved by us allows restoring the one-dimensional projection of
distribution density with enough smoothness. Afterwards by means of this
projection it was built the real profile of three-dimensional distribution in
flare star deficit region and were quantitatively estimated the parameters of
this profile [7] (the equivalent width of this region – 0.56 pc, and the
deficit measure – 47%).
The
comparison of the two-dimensional density function restored from the
three-dimensional distribution by means of modeling by inverse calculation
method with the same function obtained from the observations shows that the
realized restoration of three-dimensional distribution is correct in 1.2£r£7.0 pc region, while in the central part of the cluster 0<r<1.2 pc
the problem needs new special investigation.
The
problem of restoration of flare star three-dimensional distribution we examined
also for sliding separate 90° sectors. It was shown that the
property of flare star deficit is characteristic not only for the entire
cluster, but for each 90° sector built by continuous
sliding. Thus, the discovered region of flare star deficit is not a consequence
of a local irregular fluctuation revealed spontaneously in flare star
distribution, but just like the whole cluster it also has a spherical-symmetric distribution
around the cluster center in 2.8£r£3.5 pc area.
Thus,
this investigation mentions that the discussed property of flare star deficit
in Pleiades is real and needs physical explanation.
References
1. H. von Zeipel, Ann. Paris Obs. Mem.,
v. 25, p. F1-F101, 1908.
2. H.C. Plummer, M.N.R.A.S.,
71, 460, 1911.
3. M.A. Mnatsakanian, Rep. AS Arm., 49, 33, 1969.
4. L.V. Mirzoyan, M.A. Mnatsakanian, IBVS, 528, 1, 1971.
5. L.V. Mirzoyan, M.A. Mnatsakanian, G.B. Ohanian, in: "Flare Stars, Fuors, and Herbig-Haro
Objects", ed.
L.V. Mirzoyan, AS Arm. SSR,
6. H.S. Chavushian, A.V. Oskanian, G.H. Broutian, Astrofizika,
42, 537, 1999.
7. H.S. Chavushian, H.V. Pikichian, A.V. Oskanian,
G.H. Broutian, Astrofizika,
47, 369, 2004.
Very High Energy Gamma Ray
Sources
F. Aharonian
Max-Planck-Institut fur Kernphysik (MPK), Heidelberg,
I
will discuss the basic motivations, achievements and status
of ground based gamma-ray astronomy, and highlight the recent exciting
results related to different areas of modern astrophysics and cosmology.
STUDY OF COSMIC MICROWAVE
BACKGROUND MAPS
V.G. GURZADYAN
Yerevan Physics Institute (YerPhI),
A
review of our knowledge on the Cosmic Microwave Background (CMB) was given. The
importance of the CMB structure for understanding the geometry of the Universe,
percentage of the visible and dark matter, and its present large scale
structure was stressed. Results from COBE, BOOMERanG
and WMAP experiments were discussed. The WMAP satellite confirms the results
obtained by COBE and BOOMERanG.
COUNTS OF FAINT BLUE GALAXIES AND INTRINSIC REDSHIFTS
H.A. Harutyunian
Byurakan Astrophysical Observatory (BAO),
A
hypothesis is considered that the spectra of young extragalactic objects
possess an intrinsic redshift decreasing in the course of their evolution is
considered. A number of observational facts are presented to show that the
quasars are mostly situated at non-cosmological distances and therefore the
observed redshifts in their spectra could not be caused due to the cosmological
expansion but most probably have local origin. The possibility of revealing the
features of intrinsic redshifts in spectra of postquasar
objects is suggested accepting the majority of quasars to be local objects
ejected from nuclei of galaxies. We argue for the affected by intrinsic
redshifts luminosity function of local galaxy population made poorer in the
faint end. This approach is used to consider the problem of excess of faint
blue galaxies.
Search and study of the PMS
activity in the
compact star-forming regions
T.Yu. Magakian, T.A. Movsessian, E.H. Nikogossian, E.R. Hovhannessian
Byurakan Astrophysical Observatory (BAO), Armenia
The
work on the project started in 1998 is described. It includes cataloguization of nebulous objects in the dark clouds,
searches of new HH objects and flows, and their detailed studies, as well as
the discovery and photometry of new H-alpha emission stars in compact stellar
groups. These observations are performed mainly on 2.6m telescope in Byurakan.
As the samples the results for such fields as L1340, GM1-61, GM2-30, RNO127,
RNO129 and others are shown.
Byurakan Astrophysical Observatory (BAO), Armenia
The main
observational characteristics have now been determined for most of 1300
pulsars: puls period P, its time variations P`,
average radiation flux density at different frequencies (S400, S1400),
dispersion measure DM, rotation measure RM, pulse equivalent width W, and many
others. The enormous number of pulsar data of
different kinds that have been collected provide extensive opportunities for
their statistical use. Pulsars deserve to be considered as probes of the
interstellar medium, since their distances, determined from their dispersion
measures, are assumed to be more or less reliable for a large sample of these
objects. The main uncertainties in the procedure of determination of pulsar’s
distances are related to the inadequate knowledge of the electron density
distribution in the Galaxy. All distances of pulsars are determined now using
the model of Taylor & Cordes (1993) for the Galactic electron density
distribution.
We present here a new method, which can be used for the study of
electron density distribution in the Galaxy, without using of any model for it.
From the equation DM(R)=R∫ne(R)dR for dispersion
measure, we have ne(R)=d(DM)/d(R), where ne(R) is the
electron density in the point with distance R from the Sun. In
fact, if we have the dependence between DM and R in the plane of Galaxy for
every direction, we can obtain electron density in every point of the Galactic
plane. For the relation of DM – R we
shall take the averaged relation between observed values of DM pulsars and
values of independent distances Ri,
obtained by the independent from the DM method. The method for obtaining of Ri will be discussed
below. As an averaging procedure we use
the method, when the coordinates (l;R) (where - l is the galactic longitude, R – the
distance from the Sun) of the center of averaging region, for example, with the
constant number of pulsars, is changed smoothly in the plane of Galaxy. Then,
using the above mentioned formulae, we determine the distribution of electron
density in the plane of Galaxy, solving in fact the inverse problem, without
using of any model for electron density distribution. We have already prepared
a computing program for the proposed procedure. As a good test of the program we use the
comparison of obtained distribution with the spiral arm model of Georgelin & Georgelin,
(1976), or Taylor & Cordes, (1993). At first we used distances, obtained
from the DM data and the Taylor & Cordes (1993) model of electron density
distribution in the Galaxy. If our program is working well, using these
distances we must receive again the Taylor & Cordes model for the galactic
distribution of electron density. The calculations show good conformity of
received in this way electron density distribution with the Taylor and Cordes
(1993) model, what we see from the picture. In this program we can change the
averaging area, the averaging step, the sample of used pulsars, choosing them
by their physical or other parameters. So, if we have the homogeneous
independent from DM distances of pulsars, spread over the Galactic plane, we
can find the electron density distribution in the plane of Galaxy, using this
program.
Now
we describe the method for obtaining of independent distances Ri of pulsars. It Is generally accepted that pulsars radiate due to the loss
of rotational energy of neutron stars. Well known parameters derived from the observed
data are timing age
T=P/2P`,
(1)
and “spin-down luminosity”
E` = -4π2IP`P-3, (2)
where P and P` are period and its time
variation, I = 1045 gcm2 – is the moment of inertia of
pulsars.
We
studied the relation of radio luminosity L of pulsars from the age T and from
the “spin-down luminosity” E`. For this study we used observational data for radio
luminosity at 400 and 1400 MHz. We found a good linear correlation between Log(L) and Log(E`). The correlation becomes better, if we
use only the pulsars with age 106 < T < 108 year.
Log(L) = 0.452 + 0.209(Log(E`) –28) (3)
For
pulsars with T< 106 year and T>108 year there is no
such correlation. There is also a linear relation between Log(L)
and Log(T), where Log(L) decreases with the increase of Log(T).
Log(L) = 2.78 - 0.22Log(T) (4)
If
we have these relations for some groups of pulsars, we can use these relations
to find the new (theoretical) radio luminosity LT for all pulsars
with known parameters E` and T. This new radio luminosity can be used for the
determination of pulsars distances Ri
using their observed flux densities S
RI
= (LT/S)1/2. (5)
These
distances Ri will
be independent from the dispersion measures DM of pulsars and can be used for
the study of electron density distribution of Galaxy. We did the preliminary
study of this problem, using the mentioned relations. The result of this study
is on the fig.
It must be said that the relations between Log(L) - Log(E`) and Log(L) -
Log(T) in fact are relations between Log(L) and
observed values of period P and its time variation P` (see the formulas
(1) and (2)) . Such relations have been studied in Stollman
(1987), Vivekanand & Narayan
(1981) Andreasyan &
Arshakian (2001),
where was considered the relation of type
L = γPαP`δ
(6)
Taking its logarithm,
we obtain a linear equation in α, β and log(γ).
After the finding of
three parameters α, β and log(γ) by the
least squares method, in Andreasyan
& Arshakian (2001) this relation was used for the determination
of independent distances of pulsars. It is obvious, that this relation will
give better results than above mentioned relations (formulas (3) and (4)),
where we find and use only two parameters of linear relation between Log(L) - Log(E`), or Log(L) - Log(T).
We now study this
relation (6) using incomparably larger sample of pulsars, than in previous
works. The results of this study for various samples of pulsars are given in
Table1. Using the values of α, β and log(γ)
from the Table 1, and observed data of P and P`, we can find the LT
from the relation (6), and Ri from
the relation (5). We use these Ri
for the study of electron density distribution by the above-mentioned method
and have the preliminary result.
Georgelin Y.M. and Georgelin Y.P., Astron. Astrophys., 49, 57, (1976).
Stollman
G.M. Astron. Astrophys., 172, 152 (1987).
Taylor, J.H. and Cordes, J.M., 1993. Pulsar Distances and the Galactic distribution of free electrons.
Ap.J. 411, 674.
Vivekanand
M. and Narayan, R., J. Astron. Astrophys., 102, 315 (1981).
Byurakan Astrophysical Observatory (BAO), Armenia
By the slitless method (H-alpha filter + grizm) 22 emission stars are
discovered in the central and northeast part of star cluster NGC 7129. The 16
of them are new ones. This sample is completed up to mv< 20.0. The emissions stars are non-uniformly distributed on a field of the cluster
and concentrated in the center part. It was using V, R and I magnitudes
of more than hundred stars of the cluster we had been determined average
extinction Àv = 1.7±0.27 in research area by the method of the
least squares. On the photometric parameters (VRIJHK) the majority of emission
stars with a high probability can be related to T Tau objects.
The Catalog of AGN and its
statistical value
A.M.Mickaelian1,
M.P.Véron-Cetty2, P.Véron2
1 – Byurakan Astrophysical Observatory (BAO), Armenia
2 – Observatoie de
Haute-Provence (OHP), France
The
Catalogue of quasars and active nuclei by Véron-Cetty & Véron
(11th Edition, 2003), contains 64,866 AGN listed in three tables as QSOs, BLL,
and AGN. The Catalogue contains all AGN with published redshifts. However, the
data given are not homogeneous and the Catalogue could not be used for any
statistical investigation. Having a homogeneous set of magnitudes would be
especially important for calculating absolute magnitudes, constructing
luminosity functions and cosmological analysis. The Minnesota Automated Plate
Scanner (MAPS) catalogue (Cabanela et al. 2003), recently released, gives
0.2" rms positional and 0.2m rms photometric (magnitudes and colors)
homogeneous data for all objects present in the POSS plates with |b|>20. We
decided to cross-correlate the AGN catalogue with MAPS to make it homogeneous and
statistically useful. The results are presented, including some preliminary
analysis of different sets of AGNs.
COSMIC EVOLUTION OF COMPACT AGN AT 15 GHz
T.G. ARSHAKIAN, E. Ros, J.A.
Zensus, M.L. Lister
Max-Planck-Institut fur Radioastronomie (MPIfR), Bonn,
Germany
We
study the cosmological evolution of flat-spectrum quasars from the complete 2
cm (15 GHz) Very Long Baseline Array (VLBA) survey. The sample is complete to
flux-density limits of 1.5 Jy for positive declinations and 2 Jy for declinations
between 0 and -20 degrees, and comprises 133 active galactic nuclei. A
significant positive and negative evolutions are found for low-redshift
(z<0.5) and high-redshift (z>1.7) quasars implying that jet activity
phenomena were more populous at redshifts between z~0.5 and z~1.7. It is shown
that low- and high-luminosity quasars display different evolutionary behavior
which is supporting the luminosity dependent evolution of flat-spectrum compact
quasars.
THE OH MEGAMASER GALAXIES
Rafik Kandalyan1,
2
1 – Byurakan Astrophysical Observatory (BAO), Armenia
2 – Institute of Astronomy and Space Sciences, Al
Al-Bayt University, Jordan
The
X-ray, radio continuum and FIR properties of the OH megamaser galaxies are
discussed. Most of the radio sources in megamaser galaxies have comparable flat
radio spectra between 1.49 and 8.44 GHz, and high brightness temperature. In OH
megamaser galaxies the radio continuum is predominantly non-thermal, powered
either by compact starburst or AGN. The thermal radio emission can be neglected
in these galaxies. The observed flat radio spectra, high brightness
temperatures imply the presence of an AGN in these galaxies. On the basis of a
sample of megamaser galaxies it is found that X-ray emission is tightly related
to the OH line width. The OH line width is related to both radio continuum and
FIR emission; however the last correlation is tiny and less significant. The OH
line width, radio continuum and the X-ray are related to the central mass of
megamaser galaxies. There is a weak correlation between the X-ray and radio
continuum in megamaser galaxies, which may due to multiple up-scattered
synchrotron photons and nuclear jet activity. These results suggest that in OH
megamaser galaxies an active nucleus may dominate, although some megamasers may be powered by compact starburst.
M87 Phenomenon
S.G. Iskudarian
Byurakan Astrophysical Observatory (BAO), Armenia
M
87 is the active nucleus of Our Supergalaxy. M 87
with its immediate environment is the nearest "void". M87 is
connected with the closed loop-like superstring, with has been ejected from M
87. M 87 itself with its wide environment is a huge monopole with its field of
forces. This many-colored behavior of M 87 is result of periodic acting of the
general regularity, which acts in the micro and macro worlds of the Universe,
ensured by this way the unity of the Universe. It is the origin, formation,
ejection of the first type stellar population from the entrails of the second
one (in protogalactic stage, of course). In micro world it is b (beta) decay.
The Reflection of Ancient
Astronomical Knowledge in the Rock Art of Armenia AND AN Astronomical Method
for Absolute Dating of Rock Carvings of Constellations
Karen TOKHATYAN
Institute of History of the Armenian National Academy
of Sciences, Yerevan, Armenia
Rock
Art of Armenia was mentioned for the first time by Movses Khorenatsi who has preserved an ancient witness of Rock Art in
a marvellous form - the dream of Mesrop Mashtots. Khorenatsi’s second witness on rock carving in connection with the hero
Torq, the demiurge of sculpture. More direct is Anania Shirakatsi’s
information: “The receptors of ancestors were
more sensitive than ours,
due to which they could notice not only the movement of the Sun but
also inscibe, i.e. carve, and recognize the movements of all the other
luminaries and stars”. This may be considered as an earliest bibliographical evidence
of antiquity and trustworthiness, reliability of the rock carvings with
astronomical content. Some rock‑carvings of astronomical significance had
an applied function: measuring time, marking the time and the geographical
location. There are 30 and 31‑day solar calendars, 7, 14 and 28 or 29‑day
lunar calendars, 12-month calendars, 354/365 day annual calendars.
Some
rock carvings in Armenia represent constellations. They are discovered at the Vardenis Mountain Pass, at 2,410m a.s.l.,
near an ancient caravan road with cyclopean fortresses. The stars are
represented by dots and circles, corresponding to their brightness. It is
common knowledge from astronomy that all the stars have their proper movements.
The movements are too slow and the derivations too small in order to be noticed
by man during a lifetime, but perceptible enough to shift noticeably during
millennia. Method is based on comparing the engraved configuration of a certain
constellation with its present view, and the assumption that the image was
executed with enough precision, i.e. was similar to the shape of that
constellation at the moment of engraving. Reconstructing the shape and position
of the constellation in the past and comparing them with the view in the rock
carving, we can receive precise time it was carved, i.e. the absolute age.