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.
16 (
Editor: L.A.Sargsyan, sarl11@yahoo.com
The ArAS Newsletter in the
INTERNET: http://www.aras.am/arasnews.html
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Merry Christmas and Happy New Year
!
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CONTENTS:
1.
2. First
Byurakan International Summer School in 2006
3. The
Byurakan Observatory 60th Anniversary Meeting
4. Abstracts
of contributions in ArAS IV Annual Meeting
______________________________________________________________________________________
On
Artak Harutyunyan, 29, has graduated from the
Elena Hovhannessyan, 30, has graduated from the
We congratulate Artak and
Elena with this success and wish them future scientific achievements.
______________________________________________________________________________________
FIRST BYURAKAN INTERNATIONAL SUMMER SCHOOL
FOR YOUNG ASTRONOMERS
"OBSERVATIONAL
ASTROPHYSICS"
22-31 August 2006, Byurakan (
F I R S
T A N N O U N
C E M E N T
An international summer school "Observational
Astrophysics" will take place on
The Byurakan Observatory is one of the main
observational centers of the former
The Byurakan Observatory hosts a number of medium-size
optical telescopes, the most important being the 2.6m classical telescope and
1m Schmidt telescope. There are different modern astronomical instruments,
including the multi-pupil spectrograph (VAGR). The Byurakan Observatory holds
the Digitized First Byurakan Survey (DFBS, or the Markarian survey), containing
low-dispersion spectra for ~20,000,000 objects. Many qualified specialists work
presently in Byurakan, who are prepared to teach modern observational
astrophysics to young people. In addition, a number of well-known scientists
are invited to lecture during the school on different interesting topics.
TOPICS:
o
Ground-based Telescopes and Modern Observational Techniques
o
Space Telescopes and Space Missions
o
2D spectroscopy
o
Computers for Astronomy: Astronomical Data Reduction
o
Archives, Databases and Virtual Observatories
o
Studies of Planets, Stars, Nebulae, and Galaxies with different methods
o
Astronomical Surveys and Future Giant Projects
EVENTS:
Most of the time will be devoted to lectures (2-3
lectures daily) and practical courses (observations and data reduction). The
following events will take place during the School:
Ø Lectures on different aspects
of observational astrophysics
Ø Observations with 2.6m
telescope
Ø Data reduction with MIDAS and
IRAF packages
Ø Observations with small
telescopes
Ø Practical courses of
astronomy with computers
Ø Acquaintance with the
Byurakan Observatory and its research
Ø Visit to Orgov
Radio-Optical Telescope (ROT)
Ø Excursions to famous Armenian
sightseeing
TENTATIVE LIST OF LECTURERS AND
LECTURES:
Dr. Vladimir AIRAPETIAN (
Dr. Don BARRY (
Prof. Alec BOKSENBERG (UNESCO;
Prof. Vassilis CHARMANDARIS
(
Dr. Michel DENNEFELD (Institut
d'Astrophysique
Dr. Serguei DODONOV (Special
Astrophysical
Dr. Dieter ENGELS (Hamburger Sternwarte,
Dr. Armen GYULBUDAGHIAN
(Byurakan Astrophysical
Dr. Arsen HAJIAN (United
States Naval
Dr. Haik HARUTYUNIAN
(Byurakan Astrophysical
Dr. Rafik KANDALYAN
(Byurakan Astrophysical Observatory,
Dr. Tigran MAGAKIAN
(Byurakan Astrophysical Observatory,
Dr. Areg MICKAELIAN
(Byurakan Astrophysical Observatory,
Dr. Tigran MOVSESSIAN
(Byurakan Astrophysical Observatory,
Prof. Elma PARSAMIAN (Byurakan Astrophysical
Dr. Artashes PETROSIAN
(Byurakan Astrophysical
Dr. Levon POGOSYAN (
Prof. Massimo TURATTO (Osservatorio
Prof. Daniel WEEDMAN (
PARTICIPATION AND ACCOMMODATION:
PARTICIPATION FEES:
Registration fee:
120 $
BAO hotel:
10-15 $ per night
YSU hotel:
25-30 $ per night
Meals:
12 $ per diem
Excursion:
20 $
School Banquet:
20 $
The registration fee includes transportation of all
participants from the airport to Byurakan and back, participants' sets (bags,
etc.), welcome reception, coffee-breaks and refreshments during the working
days of the school, excursions in Byurakan and to Orgov,
and organizational expenses.
SPONSORS AND FINANCIAL SUPPORT
The Byurakan Observatory, Armenian Astronomical
Society, and Prof. Daniel Weedman (
A small number of travel grants will be distributed
for a partial support of students exceptionally from countries with limited
resources. An application for a financial support with a brief justification
should be sent to Areg Mickaelian (aregmick@apaven.am) and Elena Nikoghossian
(elena@bao.sci.am).
INTERNATIONAL ORGANIZING COMMITTEE
(IOC):
V. Charmandaris (
M. Dennefeld (
D. Engels (
H. Harutyunian (
R. Kandalian (
A. Mickaelian (Co-chair,
M. Turatto (
D. Weedman (Co-chair,
LOCAL ORGANIZING COMMITTEE (LOC):
A.M. Mickaelian (Chair), E.H. Nikoghossian
(Secretary),
DEADLINES:
CONTACT ADDRESSES:
Postal Address:
Byurakan Astrophysical Observatory,
Byurakan 378433,
Telephone:
374-10 53-27-51 (Areg Mickaelian)
374-10 26-00-58 (Elena Nikoghossian)
E-mail:
aregmick@apaven.am (Areg
Mickaelian)
elena@bao.sci.am (Elena Nikoghossian)
Web page:
Will be set up soon at BAO (www.bao.am)
and
______________________________________________________________________________________
PRELIMINARY
REGISTRATION FORM
______________________________________________________________________________________
Name:
First name:
Age:
Sex:
University, department:
Year and stage of Academic studies:
Country:
Your reasons for wishing to attend the school:
Name and address of your supervisor or a person who will
give recommendation:
Postal Address:
E-mail:
______________________________________________________________________________________
DEADLINE FOR PRELIMINARY
REGISTRATION:
______________________________________________________________________________________
THE
BYURAKAN OBSERVATORY 60th ANNIVERSARY MEETING
The Byurakan Astrophysical Observatory will celebrate
its 60th anniversary in 2006. It was founded in 1946 by our greatest scientist
Victor Ambartsumian. We plan to organize an
International Symposium devoted to this event. The meeting will take place on
The First Announcement of the Symposium will be given
in our next Newsletter at the end of March. For expression of interest to
participate and a preliminary registration, please send a message to Haik Harutyunian
(hhayk_ast@yahoo.com).
____________________________________________________________________________________
ABSTRACTS OF CONTRIBUTIONS IN
(brief texts for some of the contributions)
The 3D structure of the magnetic field of the Galaxy
R.R. Andreasyan
Byurakan Astrophysical
The activity of cosmic objects is associated in most
cases with the presence of magnetic fields of different scales, natures and
strength. The large-scale magnetic field in our Galaxy was found in 1950-th,
and till now is studied hardly using all available methods (Parker 1979), based
on the analyses of optical and radio polarization data and measurements of
Rotation Measure (RM) of extragalactic radio sources and pulsars etc. It seems
to be very important to take into account of magnetic field distribution in
galaxies, and partially in our Galaxy, when we study the formation and
evolution of galactic structural features as well as a whole morphology of
optical and radio galaxies and quasars. Many attempts have been made to find
the distribution of the large-scale magnetic field of our Galaxy. It was shown
that three classes of model are viable for the large-scale structure of
magnetic field in the disk of Galaxy: 1.
a bisymmetric spiral (BSS), in which the field direction reverses from arm to
arm (Simard-Normandin & Kronberg
1980; Sofue & Fujimoto 1983, Andreasyan
& Makarov 1989, Han et.al.,
2002); 2. an axisiymmetric spiral (ASS), with two
field reversals inside the Solar Circle, Vallee
(1991,1996), Poezd et al.,(1993); 3. a concentric ring model, Rand & Kulkarni
(1989), Rand & Lyne (1994).
In the recent study by Indrani
& Despande (1998) a model was suggested involving
a magnetic field with the spiral structure lying in the inter arm regions.
Studies of polarized radio emission from spiral galaxies (Beck et. al.1996)
show galactic-scale magnetic fields, with a pitch angle similar to that, of the
spiral arm. Observations by Beck & Hoernes (1996)
show that in the galaxy NGC 6946 also the magnetic spiral structure lies in the inter-arm region.
Halo magnetic fields also were observed in many
galaxies. The Halo magnetic fields may be: 1. Poloidal,
as in NGC 4631 (Hummel, Beck & Dahlem 1991); 2.
May be parallel to the galactic disk, as in NGC 253 (Beck et. al.1994); 3. Show
a filamentary structure, as in NGC 4666 (Dahlem et al.1997). The Halo magnetic field of our Galaxy was
studied by Andreasyan & Makarov
(1988, 1989). It was suggested that the distribution of RMs
of pulsars and extragalactic radio sources are consistent with a Halo magnetic
field of opposite sign above and below the Galactic plane. . Han et al. (1997)
(1999) obtained a similar result for the Halo magnetic field of the Galaxy, and
estimated the vertical component of magnetic field to be B=0.37
?G, directed toward the North Galactic pole. These results are in
agreement with the dipole magnetic field model for the Halo, but deformed by
the differential rotation of the Galaxy, as proposed by Andreasyan
& Makarov (1988, 1989).
So, in spite of a large number of papers studying the
structure of galactic magnetic field, there is no generally accepted model.
Here we study the 3-dimensional distribution of
Galactic magnetic field, using all available rotation measure data of
pulsars. Since the time of our earlier
studies, much more data has become available for this investigation,
particularly for more distant pulsars (e.g. Rand & Lyne
1994; Han et al. 1997). The total number
of pulsars with known values of the rotation measure -RM, now is 363. We use this
improved database for the study of 3-dimentional model for whole galactic
magnetic field. We divide the study on two part; 1. The study of the magnetic
field in the region near to galactic plane (plane component) with |z|<z_o pc, where z – is the distance from the galactic plane,
and the value of half thickness of plane component zo
can be changed in different versions of calculation; 2. The second stage is the
study of Halo component of magnetic field with |z|>z_o
pc.
It is well known that pulsars are strongly
concentrated to the galactic plane, and there are not so many pulsars in the
Halo region. Therefore we use different methods for the study of magnetic
fields of Plane component and Halo component. For the Plane component, using
data of much more pulsars, we construct the map of distribution of magnetic
field in the galactic plane. It is known that for pulsars
RM = \alpha^RxInt(n_eB_LdL),
(\alpha=8.1.10^5) (1)
DM = RxIntn_edL,
(2)
where DM – is the dispersion measure of pulsar, which
is known practically for all pulsars from the observations, BL is the component
of the magnetic field along the line of sight (in G), R- the distance of pulsar
from the Sun, ne is the electron density (cm-3), and
the integral is taken over a distance L (pc).
Equation (1) and (2) yield
<B_L> =
(1/\alpha)d(RM)/d(DM), (3)
and
B_L(DM) = (1/\alpha)d(RM)/d(DM) (4)
B_L(R)n_e(R)
= (1/\alpha)d(RM)/d(R) (5)
Here ‹BL› is the magnetic field strength averaged
along the line of sight, and BL(DM) is the line of
sight component of magnetic field strength at the point with a given value
of DM (unlike to averaged value of
‹BL›), BL(R) is the line of sight
component of magnetic field strength at the point with a distance R from the
Sun. It means, that using the RM-DM and RM-R dependences for a given direction,
it is possible to find BL(DM) for each value of DM,
and BL(R)ne(R)
for each value of R. We can find the RM-DM dependence for all directions
in the plan of Galaxy using averaging procedure similar to one presented in Andreasyan et.al (2005). That is,
we use the method, when the coordinates (l;DM) of the center of averaging region (where - l
is the galactic longitude, DM – the dispersion measure), with the constant
number of pulsars, is changing smoothly in the plane of (l;DM).
So we find the dependence of average values of RM from the average value of DM
in every direction, and from the formula (4) find the BL(DM).
This is true also for the RM-R dependence, and from the formula (5) we find the
BL(R)ne(R). In fact we are
solving the inverse problem to construct 2-dimensional model for plane component
of Galactic magnetic field with coordinates (l;DM), or (l;R).
Some of the results of calculations are given on the
maps of BL(R)ne(R) and BL(DM) (fig1 and fig.2), which
are constructed for some restrictions on the z coordinate. In the fig.1 we have
the distribution of BL(R)ne(R)
in the galactic plane (l;R). The Sun is located in
the center of the distribution. The galactic longitude l increases opposite to
the clockwise, and the center of the galaxy is directed to the right (green
point). The distance of the sun from the center of Galaxy is accepted 8.5 kpc.
On the maps pulsars are marked by circles of different color. The blue color of
circles and averaging regions indicates that the magnetic field component is
directed to the observer (RM>0), and the red color we use for the magnetic
field component directed from the observer (RM<0). As dense is the color, as
large is the value of BL(R)ne(R).
On the picture we have the distribution of BL(R)ne(R): for all pulsars with known RM
(-1800<z<1800pc); for the plane component of magnetic field (-400
<z<400pc, -400<z<0pc and (-0<z<400pc); and the distribution
for the Halo region -1800<z<-400pc and 400<z<1800pc. The restriction ?z?<1800pc for Halo region comes from the
catalogues of pulsars. On the map with -400 <z<400pc we see the reversals
of magnetic field directions from one spiral arm to another, what is consistent
with the results of previous studies (for example, see Han et al. 2002). But in
the maps with -400<z<0pc and -0<z<400pc we see large differences.
The main difference in the pictures for South and North hemispheres is the
magnetic field distribution in the direction of Sagittarius spiral arm (l ? 55o). The very strong and homogeneous magnetic field of
Sagittarius spiral arm, directed to the observer (blue color), appears only in
the North hemispheres. This distribution is consistent with the results of Andreasian et al (2003). There are also other large scale
features on the fig.1, the detail investigation of which is in progress.
The study of the magnetic field of Halo region (in
fig.1 regions -1800<z<-400pc and 400<z<1800pc.), using relatively
less observational data, is also in progress, and gives preliminary results,
that are consistent with the results of Andreasyan
& Makarov (1988,1989) and Han et al. (1997,1999).
We must note that the results, obtained from the fig.1
for Plane component of Galactic magnetic field depends strongly from the method
of estimation of pulsars distances. It is obvious, that these results reflect
the spiral arm model of electron density distribution (Taylor & Cordes, 1993), used for the estimation of pulsar distances.
It is the reason, that for the detail investigation we use also the
distribution of BL(DM). We bring here, for example,
one of these distributions (fig.2). In this picture, as one of coordinates, we
use the averaged dispersion measure instead of averaged distance from the Sun.
The galactic longitude increases opposite to clockwise (the center of the
galaxy is directed to the right). From the picture we see, that the maps for
pulsars with -20<K<20 (K=DM.Sinb pc.cm-3, b is
the galactic latitude), and for pulsars with -20<K<0 and 0<K<20 are
different. The main difference in the pictures for South and North hemispheres,
as in the picture 1, is the magnetic field distribution in the direction of
Sagittarius spiral arm. Magnetic field of Sagittarius spiral arm appears only
in the North hemisphere.
From the distribution of BL(DM) we can find the
distribution of BL(R), using the new distribution (DM)L-R (see Andreasyan et al. 2005, and Andreasyan
2004, “The Progress Repor of ANSEF Grant No.
04-ps-astroph-812-73 “THE DISTRIBUTION OF FREE ELECTRONS IN THE GALAXY”;). The
investigation of all these problems is in progress.
L I T E R A T U R E
Andreasyan, R.R.
& Makarov, A.N., 1988, Astrophysics, 28,
247.
Andreasyan, R.R.
& Makarov, A.N., 1989, Astrophysics, 30,
101.
Andreasyan, R.R.
& Makarov, A.N., 1990, Astrophysics, 31,
560.
Andreasyan, R.R.,
Hovhannisyan, M.A. & Andreasyan, M.R., 2003,
Astrophysics, 46, 341.
Andreasyan, R.R.,
Balayan, S. & Mavsisyan, V. 2005, “The
distribution of free electrons in the Galaxy'' Astrophysics, in preparation.
Beck, R., Carilli,
C.L., Holdaway, M.A., & Klein, U., 1994, A&A,
292, 409.
Beck, R. & Hoernes, P., 1996, Nat., 379, 47.
Beck, R.,
Dahlem, M., Petr, M.B., Lehnert, M.D.,
Heckman, T.M., & Ehle, M., 1997, A&A, in
press.
Indrani, C. & Deshpande, A.A., 1998, New Astron., 4, 33.
Han, J.L.,
Han, J.L.,
Han, J.L.,
Haynes,R.F., Stewart,R.T.,
Gray,A.D., Reich,W., Reich,P. & Mebold,U., 1992,
A&A, 264, 500.
Hummel, E., Beck, R. & Dahlem, M., 1991, A&A, 248, 23.
Parker, E.N., 1979, Cosmical
magnetic fields, their origin and their activity, Oxford.
Poezd,A., Shukurov,A.,
Sokoloff,D., 1993. MNRAS 264, 285-297.
Rand, R.J. & Kulkarni S.R., 1989, ApJ, 343,
760.
Rand, R.J. & Lyne, A.G.,
1994, MNRAS, 268, 497.
Simard-Normandin, M. & Kronberg, P.P., 1980, ApJ, 242,
74.
Sofue, Y. &
Fujimoto, M., 1983, ApJ, 265, 722.
Taylor, J.H. & Cordes,
J.M., 1993, ApJS, 411, 674.
Vallee, J.P., 1991, ApJ, 366, 450.
Vallee, J.P., 1996, A&A, 308,
433.
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3C 390.3 radio galaxy:
the link between the compact jet
and the variable optical continuum
T.G. Arshakian
Max-Planck-Institut fur Radioastronomie (MPIfR),
The "central engine" of AGN is thought to be
powered by accretion on a central nucleus believed to be a super-massive black
hole. The localization and exact mechanism of the energy release in AGN are
still not well understood. We present observational evidence for the link
between variability of the radio emission of the compact jet, optical and X-ray
continua emission and ejections of new jet components in the radio galaxy 3C
390.3. The time delays between the light curves of the individual jet
components and the light curve of the optical continuum are estimated by using
minimization methods and the discrete correlation function. We find that the
variations of the optical continuum are correlated with radio emission from a
stationary feature in the jet. This correlation indicates that the source of
variable non-thermal continuum radiation is located in the innermost part of
the relativistic jet at a distance ~0.4 parsecs from
the central engine. We suggest that the continuum emission from the jet and counterjet ionizes material in a subrelativistic
outflow surrounding the jet, which results in a formation of two conical
regions with broad emission lines (in addition to the conventional broad line
region around the central nucleus).
The large distance of the continuum source from the
central engine challenges the existing models in which the broad-line emission
is localized exclusively around the disk or near the central engine. It also
questions the assumption of virialized motion in the
BLR in radio-loud AGN, which forms the foundation of the method for estimating
black hole masses from reverberation mapping.
______________________________________________________________________________________
Active dwarf galaxies as
circumnuclear regions of LSB-galaxies
L.K. Erastova
Byurakan Astrophysical
It is shown that in their structure, morphology,
sizes, and luminosities, the active dwarf galaxies reveal a tight similarity to
the nuclear regions of normal in size galaxies with active nuclei. There are a
number of examples, when a dwarf galaxy turn out to be
an active nuclear region of an extended LSB-galaxy if observed in deep images.
On the basis of the abovementioned, an assumption is made that active dwarf
galaxies or some of their parts are isolated naked nuclear regions of the
LSB-galaxies having extended halos, which may not be observed at present even
with the largest telescopes. It may turn out that all or most of the active
dwarf galaxies are giant spiral galaxies with peripheries or LSB-type host
galaxies.
______________________________________________________________________________________
Cosmic expansion and phenomenon of activity
H.A. Harutyunian
Byurakan Astrophysical
______________________________________________________________________________________
Study of MgII 2800 h and k line profiles
obtained with IUE in A-type stars
J.B. Hovhannesyan
Byurakan Astrophysical
______________________________________________________________________________________
Once more about Astroparticle
S.G. Iskudarian
Byurakan Astrophysical
Observatory (BAO)
Byurakan 378433, Province
During 1993-2000 years author has presented some short
contributions to different International workshops. There are observational
facts in these contributions, speaking in favour of
the unity of micro and macro worlds of the Universe: fact of the existence of
closed looplike superstring in Our Supergalaxy (1), fact that M87 is the active nucleus of Our
Supergalaxy (2), that M87 with its immediate
environment is also the nearest "void" (3), observational facts about
existence of similar structures-similar formations of large and small scales
and later, fact also about similar phenomena of large and small scales in the
Universe (4,5), discovery of the observational facts about similar behaviour of galaxies and elementary particles (6), when
last ones are in conditions of the beginning moment of the Big-Bang, when high
energies released at high temperatures, discovery of the fundamental basis of
author's idea about subordinating of micro and macro worlds of the Universe to
the same general regularity, in which, may be, is hidden the most beautiful
symmetry in the Universe (it is ejection of the first type stellar population
from the entrails of the second type one (in protogalactic
stage, of course) (it is betta decay in micro world).
All these above mentioned observational facts,author's scientific thoughts and ideas (7,8),
author's new approaches to some aspects of extragalactic astrophysics (9,10),
all of these were presented to different international workshops and helped to
rise the new branch of science, which was called by physicists-theoreticians
very nice name "astroparticle".
It was found also a very interesting from the sight of
view of the new science observational fact. One can see physical connection
between groups N94 and N106 obviously from (11) (look at Fig. 1a,b,c (2)). The brightest members of N94 group show
distribution, liking to closed looplike superstring
(fig.1c). There is a similar connection between NGC4038-39 and NGC4027 in more
small scale. Interesting fact is about the similar populations of both
loops-the loop of superstring and the loop of NGC4038-39. Both contain only
very late type population. The loop of superstring consists from late type
galaxies (Fig.1c), the loop of NGC4038-39 consists of superassociations only. Such a similarity cannot be by
chance. Sooner it is a result of the same way of origin of the loops and
strings, but on different scales.
There has been made three contributions already about astroparticle (12-14) by author, that's why the last one
has been called "Once more about astroparticle".
R e f e r e n c e s
1.S.G.Iskudarian, "An Example of Closed Looplike Superstring". Euroconference
"The Evolution of Galaxies on Cosmological Timescales", 30th November-5th
December 1998, Puerto de la Cruz,
2.S.G.Iskudarian, "Is M87 the Active
Nucleus of Our Supergalaxy?". International
workshop on "Galaxy Clusters and Large Scale Structures in the
Universe", Sesto Pusteria
(
3.S.G.Iskudarian, "The Nearest
"Void?"", International workshop on "Observational
Cosmology: from Galaxies to Galaxy Systems" Sesto
Pusteria (
4.S.G.Iskudarian, "Similar
Structures-Similar Formations of Large and Small Scales",International
workshop on"Observational Cosmology:from
Galaxies to Galaxy Systems",Sesto Pusteria (
5.S.G.Iskudarian, "Is SN Phenomenon
Micro Scale Form of the Big-Bang", International workshop on"The Largest Explosions Since the Big-Bang:Supernovae and Gamma Ray Bursts",hosted
by
6.S.G.Iskudarian, "Similar Behaviour of Galaxies and Elementary Paricles"
International workshop on"Hubble Deep
Fields", 9-12 October, 2000,
7.S.G.Iskudarian,"The Unity of the Universe",International workshop on "Hubble Deep
Fields",6-9 May,1996,
8.S.G.Iskudarian, "The Universe of Micro
and Macro Scales", Astro Meeting-4, 24-29
November, 1997,
9.S.G.Iskudarian, "New Approaches in
Astrophysics", JENAM-2000, May 29th
10.S.G.Iskudarian,"New
Approaches in Astropysics", Nomination for the Cosmology
Prize of the Peter Gruber Foundation, March 2 -
11.M.J.Geller,J.P.Huchra, Astrophys.J.,Suppl.Ser., 52, 61, 1983.
12.S.G.Iskudarian, "Astroparticle is My Baby", Carolina Hershell Visitor Programme for
Enhance Women,
13.S.G.Iskudarian, "Astroparticle is My Baby", VAC-4,
14.S.G.Iskudarian, "How
was born Astroparticle - New Branch of Science",
International workshop on"Very High Energy
Phenomena in the Universe", Moriond, 12-19 March, 2005,
______________________________________________________________________________________
Imprints of Star-Formation
T.V. Khanzadyan
Max-Planck-Institut fur Astronomie (MPIA),
______________________________________________________________________________________
Jets in the HL/XZ Tau region
T.Yu. Magakian
Byurakan Astrophysical
______________________________________________________________________________________
Virtual Observatories
A.M. Mickaelian
Byurakan Astrophysical
The Astrophysical Virtual Observatories (VOs) have been created for construction of a modern system
for data archiving, extraction, acquisition, reduction, use and publication,
and for establishment a new environment for modern research based on all-sky,
multiwavelength, and multiepoch observations. The VOs work out standards for efficient work with the
databases, extraction, reduction and analysis of data, like Registries, Data
Models, Uniform Content Descriptors (UCD), Data Access Layer (DAL), VO Query
Language (ADQL), VOTable, VOPlot,
Simple Image Access Protocol (SIAP), Simple Spectral Access Protocol (SSAP),
etc. The Armenian Virtual Observatory (ArVO) project was created on the basis
of the Digitized First Byurakan Survey (DFBS) to make a system for its
efficient use and integrate the Armenian astronomy into the international one.
One of the main tasks for the ArVO is to create an
efficient user interface for the DFBS. The usage of this database is being
developed in the following way: the needed region of the DFBS plate with given
sizes, and the corresponding region from DSS1 and DSS2 will be extracted, the
2D spectra of objects will be retrieved and compared with templates, the 1D
spectra of objects will be available too, wavelength and intensity calibration,
and a numerical classification will be made, the DFBS catalog data for objects
will be given (position, magnitude, colors, types), other available data from
web (SIMBAD/NED/MAPS/USNO-B1.0) will be provided, cross-matching with other
catalogs will be carried out, and finally, the multiwavelength data for all
objects of interest will be available.
ArVO was officially authorized as an International
Virtual Observatories Alliance (IVOA) project in July 2005. ArVO includes also
science development, as it is the actual goal of AVOs.
It is the development of an automatic identification procedure for X-ray, IR
and radio sources using the low-dispersion spectra and all other available
databases; optical identification of ~100,000 X-ray, IR & radio sources;
development of an automatic search procedure for modeled objects; automatic
search for new bright AGN in DFBS/DSBS, etc.
______________________________________________________________________________________
Search for new bright QSOs by the core - host
galaxy ratio
A.M. Mickaelian
Byurakan Astrophysical
Though some 100,000 quasars are known, we are not
complete with the bright ones. These are especially important for detailed
studies, including their core - host galaxy relation. Surprisingly, 16th
magnitude objects may still be found. The discovery of all bright quasars is
really a problem, as there is not a single method allowing reveal them
independent of their color, presence of radio and/or X-ray, etc. However, it
seems the only feature typical for all of them is the presence of the host
galaxy. We have studied the DSS2 BRI images for all 1193 objects having B<16.5
and/or z<0.3 from the Véron-Cetty and Véron
catalog (2003) and found that about 80% of them have a point-like image in
blue, but extended in red and IR, the host galaxies being mostly red. Moreover,
the core is so weak in IR that only the host galaxy is observable. These
objects may be easily distinguished by the core - host galaxy ratio if compared
from the three colors. The objects being extended in B too,
anyway may be distinguished by this ratio. Thus, a special technology using the
multiband images allows reveal new quasars that could
not be found by radio, X-ray or other features. A search with a goal to find
all bright quasars in the region with DEC>0 and |b|>20 has been
undertaken in Byurakan. The 2.6m telescope with the SCORPIO system is being used
for the spectral identification of the candidates.
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The inner structure of stellar jets
T.H. Movsessian
Byurakan Astrophysical
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Line formation in multi-component stochastic media
A.G. Nikoghossian
Byurakan Astrophysical
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Investigation of the large-scale space orientation model of the
extragalactic double radiosources
by the inverse problems method
H.V. Pikichian, A.V. Kishinevskaya,
T. Hovhannesyan
Byurakan Astrophysical
In frame of the symmetric model of the extragalactic
double radiosources (EDR), the inverse problem of
revealing of the large-scale space orientation of their radioaxes
has been put forward and undergone analitical and
numeric investigations. The simplifying natural assumptions allowed to bring the problem to a system of integral equations,
which may be solved unanimously. In the simplest case, when a centrisymmetric orientation of radioaxes
is assumed, the problem goes to a solution of simple non-linear system of ariphmetic equations. First, a numerical modelling of real and observed distributions of observable
quantities has been done, then the ariphmetic
system has been solved for the given model by the Monte-Carlo method. In a centrisymmetric simplest model, in this way the accuracy of
the searched values of the derivable quantities has been estimated, depending
on the degree of the statistical richness of the modelled
"observational material". After such a test, the real observational
material was reduced with the same algorithm. It is worth mentioning that an
estimate close to one given formerly by Birch et al. was obtained for the
angular coordinates of the center of anisotropy, and for the third coordinate,
the distance of the center of anisotropy, all our calculations lead to
inaccurate values. The last fact, probably leads to a real necessity for
transition to calculations with axisymmetric model
rather than a simple centrisymmetric anisotropy
model.
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Spectral studies of the FBS blue stellar objects
P.K. Sinamian, A.M. Mickaelian
Byurakan Astrophysical
Spectral observations of the First Byurakan Survey
(FBS) blue stellar objects have been carried out since 1987 with a goal of
classification, discovery of new interesting objects and study of the FBS
sample in total. In 1987-1991, the Byurakan Observatory 2.6m telescope with the
long-slit spectrograph UAGS was used. These photographic spectra were digitized
by means of a professional scanner and reduced with MIDAS as for CCD spectra.
Observations for new FBS objects, as well as repeated observations for
confirmation and clarification of the classification were conducted in
1997-2000 with the BAO-2.6 and OHP-1.93 telescopes by means of modern
equipment. Altogether, 485 spectra for 406 objects were obtained, mainly for
objects in the FBS zones with central declinations +35, +39, and +43, as well
as a number of objects were observed in zones with DEC>+61. The principles
of digitization and follow-up automatic reduction of photographic spectra are
discussed. The principles of object classification as for
photographic spectra, so as for CCD spectra are worked out. New white
dwarfs, hot subdwarfs, HBB stars, cataclysmic variables, planetary nebulae, as
well as some extragalactic objects are revealed. The continuation of the survey
for blue stellar objects is being carried out on the basis of the Digitized
First Byurakan Survey (DFBS) spectra, and the selection and the preliminary
classification of objects is much more efficient.