Pre-Main-Sequence evolution of rotating low-mass stars

Kızıloğlu, Nilgün
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 the stars have differential rotations, their inner regions rotate faster than the outer regions. The effective temperatures and luminosities of rotating low-mass stars are obtained lower than those of non-rotating stars. They have lower central temperature and density values compared to those of non-rotating stars.
Astrophysics and Space Science


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...
Early phases of different types of isolated neutron star
Ankay, A; Sahin, S; Karanfil, G; Yazgan, E (World Scientific Pub Co Pte Lt, 2005-06-01)
Two Galactic isolated strong X-ray pulsars seem to be in the densest environments compared to other types of Galactic pulsar. X-ray pulsar J1846-0258 can be in an early phase of anomalous X-ray pulsars and soft gamma repeaters if its average braking index is similar to 1.8-2.0. X-ray pulsar J1811-1925 must have a very large average braking index (similar to 11) if this pulsar was formed by SN 386AD. This X-ray pulsar can be in an early phase of the evolution of the radio pulsars located in the region P simi...
ALPAR, MA; CHAU, HF; CHENG, KS; PINES, D (American Astronomical Society, 1994-05-20)
The pattern of glitches and postglitch behavior observed for the Crab pulsar (Boynton et al. 1972; Demianski & Proszynski 1983; Lyne & Pritchard 1987; Lyne, Graham-Smith, & Pritchard 1992) is strikingly different from that observed for the Vela pulsar (Alpar et al. 1993). A key question is whether the differences can be understood on evolutionary grounds. An analysis of the Crab pulsar suggests that this is indeed the case. Thus, we propose that the comparatively modest (DELTAOMEGA/OMEGA approximately 10(-8...
Age determination of the open cluster NGC 2287 (M41)
Küçük, İbrahim; Eryurtezer, Dilan (Springer Science and Business Media LLC, 1988)
We have estimated the age of the open cluster NGC 2287 (M41) by taking into account the rotation of the member stars. TheUBV photoelectric measurement values were taken from Eggen (1974). Besides the Main-Sequence stars this cluster has seven red giants, all of them above the turn-off point. Having obtained the theoretical Hertzsprung-Russell diagram from observed colour-magnitude diagram, we have discussed two methods, given in the literature, to estimate the age of the cluster under consideration. The f...
Modelling the oscillating star V1162 Ori
Civelek, R; Kiziloglu, N; Kirbiyik, H (EDP Sciences, 2003-12-01)
Evolutionary stellar models of V1162 Ori, with the latest observations of a multiperiodic delta Scuti star, have been calculated theoretically and compared with the observations. Theoretical models representative of the star indicate that it is at an advanced stage of its main-sequence evolution. Calculations have been made for two different masses, 1.80 and 1.82 M-., at different rotational speeds. Rotation was treated as a perturbation and only the first-order effect was considered. The evolutionary model...
Citation Formats
N. Kızıloğlu, “Pre-Main-Sequence evolution of rotating low-mass stars,” Astrophysics and Space Science, pp. 255–269, 1989, Accessed: 00, 2020. [Online]. Available: