1. An Analysis of Dust Shell Around Symbiotic Star CH CYGNI Mustafa Helvaci Informatics Institute, Istanbul Technical University

2. Agenda What is a Symbiotic Star? About CH Cygni?
Obervation and Modeling
Conclusion

3. Symbiotic Stars
Definition of "symbiosis" comes from biology, where it signifies the co-existence of different types of organisms living together to their mutual advantage.
Symbiotic star systems consist of double (a cool red giant star and a hot compact) or triple stars embedded in a gas/dust shell
Symbiotic stars are fascinating objects, where the cool and hot components interact with each other and influence each other's structure and evolutions by bipolar mass jet ejection
Only a few hundred symbiotic systems known
illustration credit: Marcella Contini of Padua Univ..
Artist's impression of the symbiotic star R Aquarii. Credit: Dana Berry

4. About CH Cygni
CH Cygni (IRAS ) is closest symbiotic star located only about 800 light years from Earth,
It is bright enough to be followed throughout it's cycle with just binoculars
CH Cygni system has two companion evolved stars with a period of 97d and 725d which are embedded in a gas/dust schell.
CH Cygni is an excellent laboratory for space scientistst to study in X-ray, Uv, Optical, IR and radio wavelengths simultaneously.
 The first resolved bispectrum speckle interferometry of the symbiotic binary CH Cyg:
Credit : Yuri Balega etal, 2009

5. Observations

6. Ligh Curve of CH Cygni
 The first resolved bispectrum speckle interferometry of the symbiotic binary CH Cyg:
Credit : Yuri Balega etal, 2009

7. Obsevations of CH Cygni
Biller etal, 2006

8. Theoretical Modeling of CH Cygni

9. Theoretical Modeling
The Code DUSTY (1999) , written by Ivedzic Z., Nenkova M., Elitzur M. at University of Kentucky was used for generation of this parametric study
10 different chemical composition and 18 temperature sets used in pre-determined Tau range that provides of 90,000 different theoretical models
Each model is a theoretical spectrum for a certain dust chemistry and Stellar temperature (Ts) and Dust concentration temperature (Td).

10. Theoretical Modeling tvis Temperature of Central Star T* (K)
Dust sublimation temperature
Td (K)
Chemical composition of the shell
Optical depth
tvis
LRS Err %
Total Err %
Mass los rate
M☼/year
Bolometric Flux (Fb)
W/m2
2000
1000
%90 Silikat
%10 SiC
0.50
8.6
20.5
1.0x10-6
2.36x10-9

11. Conclusion Fitting Results 19232+5008
Best Model Sc10_210.s E E-01
Comparison betw. Bogdanow and Helvaci
Bogdanov ps310.s E E+00
Helvaci Sc10_210.s E E-01