CONVECTION ZONE OF WHITE-DWARF STARS

1992-01-01
ATWEH, ZM
ERYURTEZER, D
The boundary convection zones of hot helium white-dwarf stars (WDSs) in the range 17000 K less-than-or-equal-to T(e) less-than-or-equal-to 30000 K are studied. Recently, an anisotropic mixing-length theory (AMLT) which determines the mixing-length parameter locally is applied for the convection zones calculation. Comparing with the calculations by using the (MLT), it is found that maximum velocity decreases appreciably, and the other boundary conditions are affected.
ASTROPHYSICS AND SPACE SCIENCE

Suggestions

Second order rotational effect on the oscillation frequencies of V1162 Ori
Matalgah, Ziyad; Kirbiyik, H.; Civelek, R.; Kiziloglu, N. (Springer Science and Business Media LLC, 2007-08-01)
V1162 is a delta-Scuti type variable star for which a rotational velocity of V sini=46 +/- 4 km s(-1) has been observed. The star has been modelled according to its observed parameters and oscillation frequencies. The results obtained by approximating rotation to the first order have been compared with the ones provided by new calculations that include rotation up to the second order. We found that second order rotation term should be included in frequency calculations for comparatively high rotation speeds.
Very high energy gamma rays from the composite SNR G0.9+0.1
Aharonian, F; et. al. (EDP Sciences, 2005-03-01)
Very high energy (> 100 GeV) gamma-ray emission has been detected for the first time from the composite supernova remnant G0.9+ 0.1 using the HESS instrument. The source is detected with a significance of approximate to 13sigma, and a photon flux above 200 GeV of ( 5.7 +/- 0.7(stat) +/- 1.2(sys)) x 10(-12) cm(-2) s(-1), making it one of the weakest sources ever detected at TeV energies. The photon spectrum is compatible with a power law ( dN/dE proportional to E-Gamma) with photon index Gamma = 2.40 +/- 0.1...
Reconstructed density and velocity fields from the 2MASS Redshift Survey
Erdogdu, Pirin; Lahav, Ofer; Huchra, John P.; Colless, Matthew; Cutri, Roc M.; Falco, Emilio; George, Teddy; Jarrett, Thomas; Jones, D. Heath; Macri, Lucas M.; Mader, Jeff; Martimbeau, Nathalie; Pahre, Michael A.; Parker, Quentin A.; Rassat, Anaid; Saunders, Will (Oxford University Press (OUP), 2006-11-21)
W We present the reconstructed real-space density and the predicted velocity fields from the Two-Micron All-Sky Redshift Survey (2MRS). The 2MRS is the densest all-sky redshift survey to date and includes about 23 200 galaxies with extinction-corrected magnitudes brighter than K-s = 11.25. Our method is based on the expansion of these fields in Fourier-Bessel functions. Within this framework, the linear redshift distortions only affect the density field in the radial direction and can easily be deconvolved ...
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 ...
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...
Citation Formats
Z. ATWEH and D. ERYURTEZER, “CONVECTION ZONE OF WHITE-DWARF STARS,” ASTROPHYSICS AND SPACE SCIENCE, pp. 27–36, 1992, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/65681.