Astronomy in Georgia is generally represented in Abastumani Astrophysical Observatory found in 1932. It is one of the leading scientific institutes in the country. Main fields of research are solar system bodies (including near-Earth asteroids), various aspects of solar physics, stellar astronomy (including binary stars and open clusters), extragalactic objects (AGNs), theoretical astrophysics, cosmology, atmospheric and solar-terrestrial physics. Several telescopes are operational today, as well as the instruments for atmospheric studies. In 2007 the Observatory was integrated with Ilia State University, merging scientific research and education which facilitated the growth of a new generation of researchers. There are groups of astronomers and astrophysicists in other Georgian universities and institutions as well. Georgian scientists collaborate with research centers and universities worldwide. Research groups participate in various international scientific projects. The interest in astronomy in Georgia has been growing, which increases future perspectives of its development in the country.
Keywords. Observatory – stellar astronomy – extragalactic astronomy – astrophysics – solar physics – cosmology – atmospheric physics – solar-terrestrial physics – history
1. Brief history of astronomy in Georgia
In ancient times astronomy in Georgia served as a tool for keeping track of time, seasons, establishing calendars, like in other parts of the world. The Georgian National Center of Manuscripts stores rare manuscripts starting from VII century. In XI - XIII centuries the observatories had been established in Kutaisi and Tbilisi where astrolabes had been used for observation of celestial bodies. The books in astronomy, translated from other languages and original ones had been issued (Ioanne Kartveli, Abuseridze-Tbeli). The most prominent Georgian literary work - Shota Rustaveli's poem "The Knight in the Tiger's skin" written in the XII century showed an advanced knowledge in astronomy of that epoch. The Georgian King Vakhtang VI (1675-1737) was one of the greatest Georgian educators who promoted astronomy in the country. Under his supervision, the Ulugh Beg's astronomical tables were translated and issued. Vakhtang VI's astrolabe is stored in the National museum in Tbilisi. At present astronomy in Georgia is generally represented in Abastumani Astrophysical Observatory (AAO) which is one of the leading scientific institutes in Georgia. It was established in 1932 when Georgia was a part of the Soviet Union. The first director of the Observatory from 1932 until 1992 was Evgeni Kharadze (1907-2001). Until 2007 AAO was an institute of the Georgian National Academy of Sciences. In 2007 the Observatory was integrated with the Ilia State University, where astronomical education was reestablished. The AAO is located in the South Caucasus region, on the top of the mount Kanobili with geographical coordinates N41045ꞌ, E42049ꞌ at the altitude of 1600 a.s.l., 250 km South-West from Tbilisi, the capital of Georgia. It is situated far from industrial and polluted areas and is characterized by highly transparent and calm atmosphere. The first telescope of the observatory was a 33-cm reflector built by Nikolai Ponomarev which also was the first Soviet reflecting telescope. The instrument is stored in the museum of the observatory. In 1937 the 40-cm refractor of the Carl Zeiss company was installed which operated until 1990-ies. 15 telescopes had been installed in AAO, including solar ones, as well as various instruments for atmospheric studies. In 1978 the biggest telescope of the observatory - the 125-cm Ritchie-Chretien telescope was mounted. Photographic, photometric, electrophotometric, spectroscopic, polarimetric observations, as well as theoretical studies had been carried out, studying variable and binary stars, star clusters, galaxy structure, extragalactic objects, the Sun and solar system bodies, the Moon. About 20000 photographic plates are stored in the "Glass library" of the Observatory. Some AAO data are also stored in the Strasbourg Astronomical Data Center. The atlas of dark nebulae and the lunar polarimetric atlas have been issued. The bulletin of AAO and astronomical calendar had been issued since 1960-ies.
2. Current research
Since 2007 E. Kharadze Abastumani Astrophysical Observatory (AAO) is a research institute at Ilia State University, merging scientific research and education. The research comprises almost all branches of astronomy and astrophysics: stellar and extragalactic astronomy, the Sun and solar system, theoretical astrophysics, cosmology, as well as atmospheric and solar-terrestrial physics. Although research in these fields are carried out in other institutions in Georgia as well: the Institute of Theoretical Physics at Ilia State University, Javakhishvili Tbilisi State University, School of Physics at Free University of Tbilisi.
2.1. Stellar and extragalactic astronomy
In AAO, the observations and comprehensive investigation of variably stars at different evolutionary stages, as well as binary stars have been carried out since 1930-ies. Study of close binary stars, the supergiant and pulsating variable stellar objects like RY Sct, Wolf-Rayet stars, Cyg X-1 are of particular interest (Kumsiashvili et al. 2014). The observational data is stored in the Strasbourg Astronomical Data Center – CDS (http://vizier.u-strasbg.fr/viz-bin/VizieR-2). Observations and study of flare stars and their possible mechanisms are performed in collaboration with Byurakan Observatory (Natshvlishvili and Kochiashvili 2008, Melikian et al. 2013,). The hypergiant star P Cyg and Be star EM Cep with observed flares are investigated, as well as Luminous Blue Variables and Wolf-Rayet Stars, in order to figure out the observational facts about evolutionary ties of these two types of stars (Kochiashvili 2007). Some other goals include solving the orbits of binary stars and asteroseismic investigations. Research is performed also in collaboration with the Shamakhy Observatory in Azerbaijan. The data are obtained by electrophotometric observations on the 48-cm telescope equipped with the CCD camera and UBVRI filters. Open clusters in the Galaxy are studied to reveal binary and multiple clusters using the method of determination of the cluster membership (Javakhishvili et al. 2006). The goal of research is to reveal double or multiple galactic open clusters like h and χ Persei, and their study through observations and numerical analysis. The high-energy study of blazars which are one of the most extreme class of extragalactic objects is carried out investigating their flux variability through different spectral bands, which is a powerful tool to study emission mechanisms, creating their energy budget (Kapanadze et al. 2014). It provides also a very effective tool to constrain the sizes of emitting regions, via the light-travel argument. The work is performed in collaboration with Palermo Institute of Astrophysics and Space Physics (Italy), the Swift Science Operations team (NASA) and the astronomy Department of Michigan University (USA). Optical observations of BL Lacertae objects since 1990-ies (Raiteri et al. 2015, co-authors Kurtanidze O. and other researchers from Georgia) and gamma-ray bursts (Mazeva et al. 2015, co-authors Inasaridze R. and Ayvazian V. from AAO) have been carried out on the 70-cm Meniscus telescope in Abastumani. These observations are parts of global networks. Theoretical studies of dynamics and structure of the Galaxy are carried out (Malasidze et al. 2014).
2.2 The Sun and solar system bodies
To search the near-Earth and potencially dangerous asteroids, the AAO, in cooperation with the Chugoevo Observatory of the Kharkov National University (Ukraine), participates in the ISON network and the European Space Agency mission GAIA (Thuillot et al. 2015, co-authors Inasaridze R. and Ayvazian V.). In the framework of this network, the photometric and astrometric monitoring of the near-Earth asteroids are performed which had led to the discovery of a binary asteroid (Scheirich et al. 2015, co-authors Inasaridze R. and others from AAO). One of the tasks of the AAO project is studying some physical characteristics of selected objects in the solar system (Jupiter’s Galilean Satellites, Mars) and their monitoring. A large group of AAO researchers study different aspects of the magnetoseismology of the solar atmosphere and the solar weather. The main goal of it is to study the processes in the solar interior and atmosphere using observational data and analytical-numerical simulations. It consists of the following tasks: the active region dynamics during solar flares and coronal mass ejection (CME), their prediction and solar weather; the oscillations and flows in the solar chromosphere and corona; the solar tornadoes; the mid-range periodicities in solar atmosphere, their connection to magnetic Rossby waves and the tachocline seismology; the magnetic tubes and turbulence in the solar wind; the radio-seismology of outer solar corona and solar CME; the quasi-periodic pulsations during solar flares. Satellite data are used, namely, Atmospheric Imager Assembly (AIA) and Heliospheric and Magnetic Imager (HMI) on board of Solar Dynamic Observatory (SDO). Interface Region Imaging Spectrograph (IRIS) and ESA future mission – Solar Orbiter will be used as well. Most of the project participants are young researchers, among them are 9 PhD students. International collaboration includes the FP7 project SOLSPANET, projects of Austrian Science foundation (FWF), Austria-Poland scientific-technical cooperation project (WTZ mit Polen), Austria-India scientific-technical cooperation project (WTZ mit Indien), Rustaveli National Science Foundation project with Georgian scientists working abroad. Almost 40 papers had been published by the researchers of this group during last 5 years (the latest being Zaqarashvili et al. 2015). One of the recent papers (Mghebrishvili et al. 2015) was highlighted by the American Astronomical Society (http://aasnova.org/2015/10/05/a-tornado-on-the-sun/). Characteristics of solar rotation by coronal holes, dynamics and classification of coronal holes have been studied using the data of the SOLIS Vector Spectro Magnetograph - VSM (Kitt Peak Observatory) and SDO. Rotation rates of mass centers, recognizable pieces of coronal holes and variations of their areas in different phases of the solar activity, as well as possible relations between rotation rates of coronal holes and variations of solar magnetic activity are studied (Japaridze et al. 2015). Monitoring of active physical processes and waves in the upper layers of the solar atmosphere are performed on the basis of observations with high dispersion spectrograph and field observations of the solar eclipses. Monitoring of cyclic variation of polarization parameters (temperature and density) in the middle and outer solar corona can help in searching a solution of the mechanisms of coronal heating. The CCD time sequence spectroscopic observations of the emission spectral lines of these layers are to be obtained using the large non-eclipse coronagraph equipped with high-dispersion spectrograph, as well as Lyot-type small coronagraph at Abastumani (Khutsishvili et al. 2014).
2.3 Cosmology and theoretical astrophysics
The origin of cosmic magnetic fields, their evolution and observational evidence are studied using direct numerical models of MHD during cosmological phase transition and recombination (Kahniashvili et al. 2013). Modification of the numerical code PENCIL, calculations of the radiation transfer in the early Universe, study of plasma instabilities are carried out. Large-scale structure objects (SZ effect) are studied to find traces of magnetic fields. Dynamics of reionization and influence of magnetic fields on the formation of primordial objects are investigated. The E-polarization of cosmic microwave background, measured by PLANK satellite are studied. Gravitational wave generation by MHD turbulence are to be calculated. Growth rate in the dynamical dark energy models are studied (Avsajanishvili et al. 2014). Astrophysical flows and non-linear dynamics of various objects are studied. Regular and chaotic phenomena in disk flaws in the galaxies, the accretion disks of compact and protoplanetary objects are investigated by numerical simulations, as well as dynamics of kinematically non-linear flaw in magnetized and non-magnetized continuous medium (Mamatsashvili et al. 2013). The group of astrophysicists of the Institute of Theoretical Physics at Ilia State University and School of Physics at Free University of Tbilisi are studying gamma-flares in Crab Nebula (Machabeli et al. 2015, Osmanov et al. 2015), as well as MHD turbulence in solar wind (Gogoberidze et al. 2012).
2.4. Atmospheric physics
Earth’s atmosphere and near space research group is involved in theoretical and experimental research of the Earth’s lower and upper atmosphere-ionosphere, their structural and dynamical variations at different helio-geophysical conditions, searching and monitoring of the signals produced by climate change (Didebulidze et al. 2011, Todua and Didebulidze 2014). Research include monitoring and theoretical study of the following parameters: the aerosol vertical distribution by lidar (ISTC grant, collaboration with the University of Michigan, USA), the total ozone content, mesopause temperature measurements by the spectrometer GRIPS 5 (collaboration with DLR), dynamical processes in the mesopause region by the all-sky Imager (RNSF grant, collaboration the Utah University, USA), photometric measurements of the atomic oxygen red 630 nm and green 557.7 nm lines of the nightglow spectrum. International cooperation include DLR, EARLINET and ACTRIS networks. Ground-based and satellite monitoring of stratospheric sulphate aerosol are studied by nightglow measurements (Mateshvii et al. 2013). The data of the GOMOS - the spectrometer onboard of the ENVISAT satellite are used. The reserachers work on the improvement of the aerosol retrieval algorithm. The obtained results will also be used in modeling of the daytime atmospheric limb brightness. The study is carried out in cooperation with Belgian Institute for Space Aeronomy.
2.5. Other fields
There archaeoastronomical studies are carried out of the old astro-archeological monuments in Georgia (Simonia et al. 2009). The astrobiology studies include investigation of the Mars surface irradiation by simulations (Tarasashvili et al. 2013).
3. Telescopes and instruments
At present in AAO the 70-cm Maksutov meniscus telescope, 53-cm azimuthal reflector, 22-cm reflector ORI, 40-cm double astrograph, 53-cm large and 11.5-cm small solar coronagraphs are operational. They are equipped with CCD cameras. Spectroscopic and photometric observations are carried out. The instruments for atsmopheric studies incude: aerosol lidar M-10 system, GRIPS-5 to measure the mezopause temperature, all-sky imager for measurements of some parameters of the nightglow, as well as the ozonometer. The new magnetometer to monitor the Earth's magnetic field has been installed recently. Astroclimatic conditions of Abastumani makes the location favorable for installation of advanced astronomical instruments, which is one of the main goals of the Observatory in the nearest future.
4. Education and public outreach
Astronomical education is mainly carried out at the faculty of natural sciences and engineering of Ilia State University, in bachelor, master and doctorate levels. Students are offered the programs in stellar and extragalactic astronomy, solar physics, cosmology, theoretical astrophysics, and atmospheric physics. AAO serves as a basis for the practical part of the courses. General courses in astronomy for students of all profiles are also offered. The courses in astronomy are also offered in Javakhishvili Tbilisi State University, Free University of Tbilisi and Samtskhe-Javakheti State University in Akhaltsikhe. AAO has a program for visitors which include popular lectures and showing the museum of the Observatory (made under the USAID project). Amateur astronomy and astrophotography are emerged lately and become increasingly popular in Georgia.
5. International collaboration and future perspectives
AAO researchers collaborate with many research centers and universities worldwide, including Byurakan Astrophysical Observatory in Armenia with which we have close collaboration for decades, one of them being the development of Armenian-Georgian Virtual Observatory (Mickaelian et al. 2009). The Georgian researchers have established partnerships with colleagues in Azerbaijan, Belgium, Bulgaria, Germany, France, India, Italy, Japan, Poland, Russia, Spain, Turkey, Ukraine, UK, USA and other countries. They have collaborations with NASA, DLR, are widely involved in EU scientific programs and are planning to participate in Horizon-2020 program. These collaborations were mentioned in previous chapters. The interest in astronomy and adjacent sciences in Georgia has been growing rapidly, which increases future perspectives of its development in the country.
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