Stellar dynamics

from Wikipedia, the free encyclopedia

The stellar deals with the apparent and absolute motion of stars in different star clusters and other star systems in order to derive their education and development.

This branch of astronomy has to struggle with numerous difficulties, including the huge distances, the smallness of the effects to be measured, the effect of systematic errors and the mutual influence of hundreds to millions of heavy masses.

Measurement methods

The underlying measurement methods are astrometric in nature (especially high-precision meridian circles and passage instruments), furthermore astrophotography (today also CCD sensors ) with appropriate evaluation devices (mono and stereo comparators ), as well as special astrometric satellites since the 1990s .

The primary measurement results are so-called self - motions of the stars in two components (right ascension, declination) on the celestial sphere; they are usually in the range of a few 0.01 "per year, with very close stars also 1-10". Multiplied by the distance (see annual parallax ) results in the linear movement - typically a few 10 km / s. The third component is the radial velocity (in the viewing direction).

Motion analysis of star clusters and galaxies

In particular, stellar dynamics investigates how star clusters and galaxies form, how they develop and decay, through precise analysis of the movements of space . She uses long-term series of measurements using astrometry, photo plates and satellite scanning, the changes of which result in the star movements. The theoretical model is made up of Newton's axioms and general relativity .

Special methods have been developed for the study of star associations and currents . Such groups of stars were formed together and move almost parallel through our galaxy, u. a. the nearby group of bears of around 50 stars that pass our solar system all around. However, such analyzes have to be adjusted around two delicate influencing factors: the sun apex (movement in the direction of the constellation Hercules) and the locally different rotation around the center of the Milky Way (approximately 200–250 km / s), which in turn depends on the exact mass distribution (see also astronomical Speed ​​measurement ).

Computer simulations

With the growing use of mainframe computers and partly also supercomputers , very extensive simulations of the movement in star systems became possible, which created a so-called "experimental" stellar dynamics. Different models are calculated and compared with observation data. In this way, the mutual influence of the celestial bodies - the multi-body problem that was insoluble until recently - can be treated mathematically.

See also

Web links