A r A S N e w s
N E W S L E T T E
R OF
THE
ARMENIAN ASTRONOMICAL SOCIETY ( A r A S )
No. 11 (
Editor: T.Yu.Magakian, tigmag@sci.am
The ArAS Newsletter in the
INTERNET: http://www.aras.am
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CONTENTS:
1)
2) Armenian astronomers in JENAM-2004
3) 75th anniversary of Prof.
Hrant Tovmassian
4) Awards to Armenian
astronomers
5)
6) New
7)
______________________________________________________________________________________
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, ArAS Co-President, followed by a report by
Areg Mickaelian, another ArAS Co-President, who presented the
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 (USA), Executive Director of the Jinishian foundation.
______________________________________________________________________________________
Armenian astronomers in jenam-2004
The 13th Joint European and
National Astronomical Meeting in 2004 (JENAM-2004)
"The
Many Scales in the Universe" took place on September 13-17 this
year in
Oral contributions:
Session #2: "Diffuse
galaxies, a keystone for galaxy evolution" (P.Prugniel, I.Chilingarian, O.Sil'chenko);
Session #3: "Microquasar as gamma-ray sources"
(V.Bosch-Ramon, J.M.Paredes, G.E.Romero, F.Aharonian);
Session #4: "Solar cycle and large-scale magnetic field
data" (V.N.Obridko, K.M.Kuzanyan,
B.D.Shelting, D.D.Sokoloff, V.G.Zakharov);
Session #5: "DFBS and the Armenian
Virtual Observatory" (A.M.Mickaelian)
Posters:
Session #2: "Cosmic evolution
of compact AGN at 15GHz" (T.G.Arshakian),
"MIGALE. The databases" (I.Chilingarian,
P.Prugniel),
"The SBS samples of
NLQSOs and NLS1 galaxies" (I.Cruz-Gonzalez, J.A.Stepanian, E.Benitez, V.H.Chavushian),
"Spectroscopic observations of Byurakan-IRAS galaxies" (A.M.Mickaelian);
Session #3: "Abundance analysis of some bipolar type I
planetary nebulae" (O.Lorente, A.Riera, B.Balick, G.Mellema, K.Xilouri, Y.Terzian);
Session #5: "ASPID: a large source of spectral data" (I.Chilingarian, V.Afanasiev, E.Afanasieva,
A.Belinski),
"The first Russian
robotic telescope" (A.Krylov, V.Lipunov, V.Kornilov, G.Borisov,
D.Kuvshinov, A.Belinski, I.Chilingarian,
M.Kuznetsov, S.Potanin, V.Vitrischak, G.Antipov).
EAS Council and Business
meetings were held as well. The importance of the document "Investment
priorities in the European astronomy" was stated presented to the European
Union. It includes also the contribution by the
JENAM-2004 was a good chance
for meeting other scientists, discussions, exchange of experience, and enjoying
the scientific and friendly atmosphere in
______________________________________________________________________________________
75th anniversary of prof. hrant tovmassian
Prof. Hrant Tovmassian, one of the famous Armenian
astronomers, celebrated his 75th anniversary.
Hrant Mushegh Tovmassian was
born on
Prof. Tovmassian's main
research fields are radiogalaxies, radio properties of Markarian galaxies,
space astronomy, groups of galaxies, flare stars. Tovmassian participated in
the evaluation of the Byurakan classification of the central parts of galaxies.
He detected radio emission from many galaxies with abnormal spectra and colors,
and proved Markarian's suggestion that these galaxies partly have non-thermal
optical emission. He studied also radio emission of more than thousand
Markarian galaxies. On the basis of radio observations Tovmassian showed that
irregular galaxies of M82 type are young objects. He carried out observations
of radio emission of a few hundred clusters of galaxies and a consequent
identification of detected radio sources with individual galaxies.
By means of radio continuum
(HII) and monochromatic (HI) observations of about 20 young stellar clusters
Tovmassian showed that expanding gas clouds exist around some of them. Spiky
flares of duration of a few tenths of a second have been detected for flare
stars by observations with specially constructed two-color fast photometer.
Tovmassian was the Principal
Investigator of the Glazar space
telescope, launched on the Mir Space Station in 1987. Tovmassian was the Head
of the Ashot space project as well.
Tovmassian showed that
compact groups (CG) of galaxies are real physical formations and that they are
embedded in loose groups in their surroundings. He concluded that CGs are
stable, and rotating configurations. He showed that the assumed enhanced X-ray
emission of CGs is not real, and is mostly due to underestimation of the radial
velocity dispersion caused by projection effects. It has been shown that poor
groups of galaxies are also stable and rotating systems.
Prof. Tovmassian published
more than 150 scientific papers in scientific journals, about 45 papers in the
proceedings of International Conferences, 12 books, including monographs,
textbooks for schools and university courses, and popular books being important
for popularization of astronomy in
He was a member of Editorial
board and Editor-in-Chief (1986-1991) of "Communications of the Byurakan
Observatory", member of editorial boards of "Astrofizika"
(1969-1986) and "Zemlya i Vselennaya" (1975-1996) journals. Tovmassian
was a member of BAO Scientific (1969-1992) and Specialized (1976-1992)
Councils, IAU (1967), EAS (1990), Mexican Scientific Society (1994), and
On behalf of the Armenian
Astronomical Society we wish Prof. Tovmassian good health, success and new
scientific achievements.
_____________________________________________________________________________________
AWARDS TO ARMENIAN ASTRONOMERS
We are happy to inform about
the achievements of our two members. Dr. Armen Oskanian, a Byurakan
observatory fellow also teaching in the "Quant" physical-mathematical
college, was recognized as the best
teacher of the year in natural sciences in
Lusine
Sargsyan, also a Byurakan fellow, has been announced as the winner of the annual award for young Armenian scientists
established by the Gyulbekyan foundation and Armenian centre for social
studies. We wish Armen and Lusine more scientific productivity and new
achievements in the future.
______________________________________________________________________________________
For the first time,
______________________________________________________________________________________
NEW
In August, three new
astronomers entered ArAS: Dr. Felix Aharonian, a leading
scientist in gamma-ray astronomy (Max-Planck-Institut fur Kernphysik,
Heidelberg, Germany), Dr. Vagharshak Sanamian, the oldest
Byurakan fellow working in radioastronomy, and Elena Hovhannisyan, one of the youngest Byurakan fellows working in
the field of young stellar objects.
______________________________________________________________________________________
Many
Beneficiary Bank | Corresponding Bank | For Further Credit To:
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Bank
Swift Address: | Beneficiary
Bank A/C No. | A/C No. 001-157395-101
MIDLAM22 | 000-05145-4 |
With HSBC Bank
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Region Full member Junior
member
Other countries: USD 30 USD
15
______________________________________________________________________________________
30-31 August 2004, Byurakan
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 –
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,
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),
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),
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).
Vivekanand
M. and Narayan, R., J. Astron.
Astrophys., 102, 315 (1981).
Byurakan Astrophysical Observatory (BAO),
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),
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),
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),
2 –
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),
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
Karen TOKHATYAN
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