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Revista mexicana de astronomía y astrofísica
Print version ISSN 0185-1101
Rev. mex. astron. astrofis vol.51 n.2 Ciudad de México Oct. 2015
Kinematics and velocity ellipsoid of the solar neighborhood white dwarfs
W. H. Elsanhoury,1'2 M. I. Nouh,1'3 and H. I. Abdel-Rahman1'4
1 Astronomy Dept., National Research Institute of Astronomy and Geophysics (NRIAG), 11421, Helwan, Cairo, Egypt. (welsanhoury@gmail.com).
2 Department of Physics, Faculty of Science and Arts, Northern Border University, Rafha Branch, Saudi Arabia.
3 Department of Physics, College of Science, Northern Border University, Arar, Saudi Arabia.
4 Department of Mathematics, Faculty of Science, Shaqraa University, Shaqraa, Saudi Arabia.
Received January 10 2014.
Accepted May 25 2015.
RESUMEN
Con el objeto de determinar la distribución de velocidades de las enanas blancas en el entorno solar utilizamos las componentes de la velocidad espacial. Utilizamos dos muestras, las más cercanas que 20 y 25 pc. Además, calculamos el movimiento solar y las dispersiones de velocidades para cuatro sub-muestras, a saber, DA, no-DA, enanas blancas calientes, y frías. La comparación de nuestros resultados para las muestras de 20 y 25 pc da como resultado una buena concordancia, mientras que los resultados de las comparaciones entre las otras sub-muestras no concuerdan. Se discute la dependencia de las dispersiones de velocidades y el movimiento solar de la composición química y la temperatura efectiva.
ABSTRACT
To determine the velocity ellipsoid of the solar neighborhood white dwarfs, we use the space velocity components of stars. Two samples of white dwarfs are used, the 20 pc and 25 pc samples. Beside the two main samples, the solar velocity and velocity dispersions are calculated for four subsamples, namely DA, non - DA, hot and cool white dwarfs. A comparison between the results of the 20 pc sample and those of the 25 pc sample gives good agreement, while the comparison between the other subsamples gives poor agreement. The dependence of the velocity dispersions and solar velocity on the chemical composition and effective temperatures is discussed.
Key Words: solar neighborhood stars: kinematics and dynamics stars: white dwarfs.
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