Letters of Intent received in 2017

LoI 2019-2016
Binary Systems: The key chart to understand stellar evolution

Date: 9 September 2019 to 13 September 2019
Category: Non-GA Symposium
Location: Cataract Pyramids Hotel, Egypt
Contact: Somaya Saad (saadmhsaad@gmail.com)
Coordinating division: Division G Stars and Stellar Physics
Other divisions: Division F Planetary Systems and Astrobiology
Co-Chairs of SOC: Hadrava, Peter (Charles University)
Stephan, V (Astronomy Institute)
Adela Kawka (Astronomy Institute)
Shengbang Qian (Yunnan Observatory of the Chinese National Academy.)
Liying Zhu. (Yunnan Observatory of the Chinese National Academy.)
Co-Chairs of LOC: Somaya Saad (National Research Institute of Astronomy and Geophysics)
khaled Edris (Al Azhar University)
• Nassim Seghouani, (Centre de Recherche en Astronomie, Astrophysique et Géophysique)
Zinab Awad (Cairo University)
Magdy Hanna (National Research Institute of AStronomy and Geophysics)



1) Binary and multiple systems: kinematics, and dynamics
2) Observational tools: (astrometry, photometry, spectroscopy, polarimetry)
3) Binary systems: impact on astronomy in general
4) Binary Systems data base, ground and space mission
5) Modeling and codes for binary and multiple systems
6) Binary systems and planetary science
7) Binary systems :standard distance calibrators,
8) Period Changes
9) Interacting Binary systems and its relation to: high energy astrophysics, galactic chemical evolution and cosmology
10) Binary and multiple systems in galactic and globular clusters, structure and evolution,



NON GA Symposium
TITLE: Binary Systems: The key chart to understand stellar evolution

#It has been known for centuries that stellar variability is very huge in scale. As stars evolve some pulsation on time scale ranging from second to years, other stars vary irregularly. Study of each particular type of stellar variation can shed light on the structure and life history of stars.
#It is thought that about half of the stars in the sky are in multiple systems, consisting of two or more stars in orbit about the common centre of mass. In most of these systems, the stars are sufficiently far apart that they have little impact on one another, and evolve independently of one another, except for the fact that they are bound to each other by gravity. In close binary systems the distance separating the stars is comparable to their size. So, the outer layers of the stars can become deformed by the gravity of the companion which influence the transfer of matter from one star to the other with far-reaching consequences for the evolution of the two stars.
The eclipsing Binaries are consider as powerful tools for testing stellar structure and evolution models, where the main stellar parameters of the binary companion, mass, radii, luminosity, … can be accurately determined from the comparing of the predicted model with the observed one.
Eclipsing binaries can also be used as astrophysical laboratories propping the internal structure, core convection, and evolution of some more energetic binaries. Cataclysmic Variables (CVs) which are binary systems consist of a compact white dwarf primary and an M-type secondary filling its Roche lobe. Much attention is focused on CVs because they provide valuable information on final stages of stellar evolution and on accretion disks. Also the X-ray Binaries have a neutron star or black hole component. The X-rays are generated by the accretion of gas onto the degenerate star from a non-degenerate companion. Modeling the star X-ray binaries complement the information on their physical properties (such as masses, radii, rotation and magnetic fields) obtained from pulsar studies.
#The occurrence of binary systems in star clusters is very frequent (Abt 1983), indicating the relationship between the dynamical processes and physical content, and give a good understanding for the dynamical evolutionary history of the host cluster. Binary variables stars in the open and globular clusters can provide an independent measurements for the physical parameters of the host clusters, such as age, distance, metallicity and so on. During the past two decades there are three distinct developments that had a great impact in deriving the basic astrophysical quantities describing close binary systems. The first one was the development of the Roche model for light curve analysis, the second one was the invention of new methods in deriving radial velocities for close binary systems and the third one is the simultaneous solution of photometric and radial velocity curves.
#Interacting binaries are considered an important players in stellar evolution, the more massive the stars, the more important the impact of binarity. The most critical phase of evolution in the lifetime of these binaries is the moment of mass-transfer. However, with many known low and intermediate mass stars there is no much known massive ones.
#Accretion disks continue to be an active area of astrophysical research, both theoretical and observational. One of the reasons for the continued interest in this phenomenon is the ubiquity of accretion disks, from protostars and protoplanetary disks to binary stars, gamma-ray bursts, and active galactic nuclei. The orbital motion of a semidetached binary can prevent the mass that escapes from the swollen secondary star from falling directly onto the primary. Instead, the mass stream goes into orbit around the primary to form a thin accretion disk of hot gas in the orbital plane,
# Recently, the space missions provided us with a tremendous amount of data through space observations, which has improved our knowledge of the structure and evolution of the universe. Which cannot be ignored the missions of the binary systems, that have contributed significantly in solving many issues related to this research area and confirmed the presence of exo-planets which is considered as one of the most interested field of research. The study of binaries and, in particular, interacting binaries provides insights into nearly all areas of astrophysics. Moreover, the study of extragalactic, interacting binaries now makes it possible to explore stellar structure and evolution in galaxies with evolutionary and chemical histories vastly different from our own galaxy. Extragalactic binaries are beginning to play an important role in cosmology as primary distance indicators.
# We are aiming in light of the above to bring together all scientists that work in the related fields of interest “ stellar binarity and multiplicity, from close to wide systems” to discuss and present a well-balanced scientific program covered almost the main research in the physics and evolution of close binaries. The advances on the underlying physics and observational techniques in addition to many other poorly understood aspects in this subject will be presented.
# For Education Public Outreach (EPO), We also planning to organize one day astronomy workshop at Kottamia Observatory 2-m reflector Telescope 70 km eastern desert. The workshop will be very excellent opportunity to charring the progress and the awareness of the Astronomy and space sciences with the general public.