The Varıable Stars Research Group
This study group aims to study cataclysmic variable star observations in order to uncover the characteristics of variability and the reason of the variations. Main goal of this research is to use the knowledge on cataclysmic variable stars to reveal the source of the variabilities and to understand the normal and variable stars. Moreover, period variations observed in the eclipsing binary stars and modelling them is also hot topic for the study group. These studies primarily aims to define the internai structure and system dynamics by understandingc the mechanisms that cause period change . Researchers use the telescopes of the TÜBİTAK National Observatory and İST60 telescope of the Department where it settles in Çanakkale Ulupınar Astrophysics Observatory.
The Galactic Structure and Multi-Color Photometry Research Group
This research group examines the physical parameters of the stars in the Galaxy using various photometric systems and by doing so investigates the formation, evolution and current structure of the Milky Way Galaxy. We use RGU and UBV photographic photometry; Strömgren for photoelectric photometry; UBV, Vega, Sloan and 2MASS for CCD photometry. With Sloan photometry our research group determines the absolute magnitude and metallicity of stars using our own methods. Separation of stars into Galactic populations and determination of the Galactic model parameters are also performed with our own methods. The most prominent contribution of our research group to the scientific literatüre is the Galaxy model parameters are function of the stellar mass. Our group are collaborating with international institutions like Basel Astronomy Institute (Switzerland), Cambridge University Astronomy Institute (England).
The Solar Research Group:
Systematic Solar observations, which was devised as drawing the places of the Sun spots on a 10 cm projection disc which then progressed into 25 cm projection disc with detailed photosphere drawings and later added the chromosphere observations using narrow band H-alfa observations that has been continued up until today, have been started at İÜ Observatory in 1945 for the first time in Turkey.
Solar photosphere and chromosphere observations are made by two refractors with 13 cm 200cm and 12cm x 232cm aperture and focal length mounted on an astrograph with 30 cm aperture as long as the weather conditions allow with the contribution of researchers from every research group via hand-drawings and photographing.
Additionally, research made by the Solar Research Group members can be listed below:
- Chromosphere Dynamics: Investigation of the chromospheric oscillations and fine structure components using the 2-D spectroscopy (in collaboration with the Germany-Göttingen University Observatory).
- Fraunhofer Line Asymmetry: Determination of the photospheric convection and Dynamics that contribute to the line formation by measuring the absorption line profiles
- Cyclical Activity: Follow-up of the 11-year Solar activity; investigation of morphological and evolution of the chromospheric activities and sun spot groups.
Extra-Galactic Astronomy and Observational Cosmology Research Group
Extra-Galactic astronomy studies in our Department is one of the thriving branches in our country. Our research groups’ main interests are starting with the determination, distribution and multi-wavelength investigation of the galaxy clusters; characterising the star formation activities, structural and photometric properties of the elliptical galaxies in various environment and generally the effects of circum-galactic environment on the galaxy evolution. Studies on this field recently embodied and supported with both national and international projects. One of the leading projects is the XMM Ultimate Extragalactic Survey (XXL) carried out with the XMM-Newton satellite of the European Space Agency. Our group mainly collaborates with the Nice Observatory (France) including other international institutions.
Stellar Atmospheres Research Group
Our dear professor, the late Prof. Dr. The "Star Atmospheres" studies, which started with Nüzhet Zihni Toydemir Gökdoğan, are still continuing in our Department. The essence of the studies is based on detailed spectral analyzes of especially B, A, F, G type main sequence stars, B, A, F type special stars and supergiant stars. In our studies, qualitative and quantitative analyzes of the atmospheres of the stars in question are carried out, and it is aimed to contribute to the research of the chemical composition of the Galaxy by revealing the chemical abundance anomalies and their causes.
Especially since 1985, the studies carried out in connection with The Citadel Department of Physics (USA) and the Dominion Astrophysical Observatory (Canada) (especially in collaboration with Prof. Dr. Saul J. Adelman) benefit from the high separation power spectra obtained by new observation techniques. Continuously developed atmosphere analysis software is used. Although the assumption used in the analyzes is generally LTE, the recent increase in the processing power of computers and the development of software related to the NLTE assumption, which includes much more complex mathematical details than LTE, have made it possible to use NLTE analyzes in our studies.
In the near future, it is planned to carry out such analyzes with our own data, with the introduction of the spectrometer at TUG.
High Energy Astrophysics Research Group:
In our department, the nature of x-ray emissions of various x-ray point sources, especially X-Ray Faint Isolated Neutron Stars and Cataclysmic Variables, is tried to be understood by analyzing the observation data of x-ray satellites such as Chandra, XMM-Newton, RXTE, ROSAT, ASCA. In addition, the nature of gamma-ray bursts is tried to be understood with the ROTSE-IIId telescope installed at TUG within the framework of the ROTSE project and the gamma-ray burst follow-up observations made from TUG.
(https://highenergyastro.istanbul.edu.tr/)
