Double shell burning phase of intermediate mass Population III stars

Kızıloğlu, Nilgün
The evolution of Population III intermediate mass stars of 5, 7, and 9M ⊙ has been studied after the core He-exhaustion phase. There are two energy producing regions within the stars; one is H-burning shell and the other is He-burning shell. During the double shell burning phase, the evolution does not proceed on the asymtotic giant branch and the second dredge-up does not appear, hence, there is no change in the surface composition of the stars. The final state of these stars are important in modelling the galactic evolution.
Astrophysics and Space Science


Main sequence for rotating stars of intermediate mass
Eryurtezer, D; Kırbıyık, Hayrettin; Özkara, N (Springer Science and Business Media LLC, 1986)
We have investigated the evolutionary behaviour of intermediate mass (2, 3, 4, 5, and 7M ⊙) Population I stars, assuming two different rates of rotation at the threshold of stability. In the first part of the study, stars are assumed to start with a critical rotation (fast rotation model) and to progress to the point of rotational instability. The stars evolve by losing mass and become rotationally unstable before they reach the zero-age Main Sequence. It is argued that multiple star systems might be forme...
Pre-Main-Sequence evolution of rotating low-mass stars
Kızıloğlu, Nilgün (Springer Science and Business Media LLC, 1989-4)
The evolutionary behaviour of rotating low-mass stars in the mass range 0.2 and 0.9M ⊙ has been investigated during the pre-Main-Sequence phase. The angular momentum is conserved locally in radiative regions and totally in convective regions, according to a predetermined angular velocity distribution depending on the structure of the star. As the stars contract toward the zero-age Main Sequence, they spin up under the assumption that the angular momentum is conserved during the evolution of the stars. When ...
Pregalactic-primordial low-mass stars
Kızıloğlu, Nilgün Gülşan; Eryurt, Dilhan Ezer (Springer Science and Business Media LLC, 1987-8)
The Main-Sequence positions as well as the evolutionary behavior of Population III stars up to an evolution age of 2×1010 yr, taking this time as the age of the Universe, have been investigated in the mass range 0.2 and 0.8M ⊙. While Population III stars with masses greater than 0.3M ⊙ develop a radiative core during the approach to the Main Sequence, stars with masses smaller than 0.3M ⊙ reach the Main Sequence as a wholly convective stars. Population III stars with masses greater than 0.5M ⊙ show a bright...
Radial and nonradial oscillations of 44 Tauri
Civelek, R; Kiziloglu, N; Kirbiyik, H (American Astronomical Society, 2001-10-01)
Evolutionary stellar models of 44 Tauri, a multiperiodic delta Scuti star, have been developed theoretically and compared with earlier observational reports. The models depict 44 Tau at the hydrogen-shell-burning stage, when it is in radiative equilibrium with a very thin surface convective layer. Using the models, we performed calculations to obtain radial and nonradial adiabatic oscillation frequencies, and the equations were treated linearly. The results showed that the radial fundamental (6.899 cycles d...
Instability of radial oscillations of Wolf-Rayet star models
Kırbıyık, Halil (Springer Science and Business Media LLC, 1987)
By taking some evolutionary models of an initially 60M ⊙-star, their radial vibrational stabilities have been investigated. These models, evolving with mass loss, are in the advanced stages of their evolution, and burn He in their cores. Calculations have been performed for the first and second harmonics as well as for the fundamental mode; and some of these models were found to be vibrationally unstable in the fundamental mode.
Citation Formats
N. Kızıloğlu, “Double shell burning phase of intermediate mass Population III stars,” Astrophysics and Space Science, pp. 343–354, 1988, Accessed: 00, 2020. [Online]. Available: