Statistical tests of distribution of perihelion points of longperiod comets.
Abstract
Modification of Fisher's method (1953) of testing a hypothesis on a distribution of points on a sphere to determine whether the perihelion points are uniformly randomly distributed in each hemisphere is presented. Since comets with perihelia in the north of the ecliptic are more likely to be discovered than those in the south, the distributions of perihelion points in the north and south of the ecliptic should be separately investigated to determine if they can be considered as samples taken from a population with uniform distribution in each hemisphere. It is shown that: (1) when comets are taken as a whole, the nullhypothesis of uniform distribution can be rejected, and (2) when comets are classified according to their perihelion distances (q), the nullhypothesis of uniform distribution cannot be rejected only for comets q greater than 1 AU and beta (ecliptic latitude of perihilion) greater than O. In addition, statistical tests are made regarding the nullhypothesis that the preferred direction of perihelion distribution is close to the solar motion apex by randomly choosing the same number of comets with positive beta as the number with negative beta. It is concluded that the perihelion points of absolutely bright comets are strongly distributed in the direction of the solar apex.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 October 1979
 DOI:
 10.1093/mnras/189.1.45
 Bibcode:
 1979MNRAS.189...45Y
 Keywords:

 Comets;
 Perihelions;
 Statistical Distributions;
 Statistical Tests;
 Apexes;
 Hemispheres;
 Monte Carlo Method;
 Random Processes;
 Solar Rotation;
 Astrophysics;
 Comets:Orbits