| Title |
Deguonis žvaigždžių atmosferose: spektro linijų formavimasis ir gausa (disertacijos santrauka) / |
| Translation of Title |
Oxygen in stellar atmospheres: spectral line formation and abundances (thesis summary). |
| Authors |
Prakapavičius, Dainius |
| Full Text |
|
| Pages |
31 |
| Keywords [eng] |
stellar atmospheres ; stellar abundances ; hydrodynamics ; convection |
| Abstract [eng] |
Oxygen abundance in stellar atmospheres is an important indicator of the evolution of stellar systems. It is known that convection and non-equilibrium radiation transfer effects influence formation of stellar observables, but the investigations of these effects are rather scarce. In this Thesis we present a new oxygen abundance determination results that is based on 3D hydrodynamical CO5BOLD model atmospheres and non-equilibrium radiation transfer. By using this methodology and observed line profiles of OI triplet (777 nm) in a Solar spectra, we determined a Solar photospheric oxygen abundance log A(O) = 8.76 ± 0.02, which matches the abundance determined from the helioseismic measurements quite well. The properties of molecular (including oxygen-bearing) line formation in the atmospheres of red giant stars were also investigated. It was found that horizontal temperature fluctuations significantly strengthen molecular lines in stellar spectra (especially, that of metal-poor stars) and the 3D-1D abundance corrections might reach –1.8 dex. Also an investigation of oxygen abundance in an atmosphere of a metal poor red giant HD 122563 was performed: by using 3D hydrodynamical model atmosphere and molecular OH spectral lines in the UV (310-330 nm), log A(O) = 6.23 ± 0.13 was determined. |
| Dissertation Institution |
Vilniaus universitetas. |
| Type |
Summaries of doctoral thesis |
| Language |
Lithuanian |
| Publication date |
2017 |
