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Orbits and the velocity structure of stars near the sun

Koot, D.H. (2017) Orbits and the velocity structure of stars near the sun. Bachelor's Thesis, Astronomy.

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In this research project I have investigated the influence of a static long and a short bar on the structure in velocity space in the Solar neighbourhood compared to the results of an axisymmetric model. This has been done by integrating the orbits for 42773 stars within a range of 300 pc of the Sun with a relative parallax error < 10%. After this, the positions and velocity distributions in the same area have been plotted to look at the differences in velocity space. It was found that the stars that originate from the Hercules stream do return in the same region in velocity space, but only after an even number of azimuthal periods in their own frame for the axisymmetric model. The short bar makes for shorter azimuthal periods than the long bar, which is similar to the axisymmetric model. The shape of the velocity distribution of the short bar is however more similar to the velocity distribution of the long bar. Since a static bar was used, there is no influence of bar resonance, which is believed to be the actual cause of the Hercules stream.

Item Type: Thesis (Bachelor's Thesis)
Degree programme: Astronomy
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 15 Feb 2018 08:31
Last Modified: 15 Feb 2018 08:31

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