Rare doctoral thesis by one of the greatest astronomers of the 20th century. The work discusses high velocity stars in the Milky Way. It shows that asymmetry in stellar motions is restricted to high velocity stars and that the highest velocity stars only appear in certain parts of the Milky Way, which was new information at the time. The present work is one of Jan Hendrik Oort's (1900-1992) first publications. It is very rare on the market, as we have not been able to find it in any sales records of the past 100 years.
Oort studied astronomy at the University of Groningen, under supervision of astronomer Jacobus Cornelius Kapteyn (1851-1922), who discovered that the movements of stars are not random. Oort later discovered that the Milky Way rotates using his and Kapteyn's findings about stellar velocity. Oort was a pioneer in the field of radio astronomy and made significant contributions to our understanding of the Milky Way. He discovered the galactic halo in 1924, was the first to find evidence for dark matter in 1932, and hypothesised in 1950 that all comets come from a common region in the Solar System, which is now called the Oort cloud. According to the European Space Agency, "few astronomers have made so many important contributions to so many different fields in astronomy as Oort has."
With a white, round label mounted on the foot of the front wrapper with a manuscript shelf mark, the same number written at the top of the title-page, a library stamp at the bottom of the title-page and the same stamp on the blank verso of the title-page. The front and back wrappers are detached, but still present. Otherwise in good condition. Cf. Epping, M., Jan Hendrik Oort: world-famous yet unassuming astronomer, 2019. Website Universiteit Leiden; Jan Hendrik Oort: Comet pioneer, 2004. Website European Space Agency.