We conclude that the distribution of the semi-major axes of extrasolar planets around solar-like stars and of planets in our own inner Solar System, is consistent with a clustering around quantized values given by , where km/s, and n is integer.
Recall that comparing the planetary systems one with another in terms of is required already in Newton's theory of gravitation (and in Einstein's theory), since the star mass gives the natural length unit of the whole system, as can be seen e.g. in the expression of Kepler's third law or of Newton's law of gravitation.
Independently of our theoretical approach, one can therefore verify in a purely empirical way that the exoplanet semi-major axes are distributed, once related to their star mass, in the same way as in our inner Solar System, so that, in opposition to the standard claim, we conclude that all exoplanetary systems discovered so far are similar to our own system.
We finally recall that the prediction that planets should be found around AU/ and 0.17 AU/ was made in a "blind" way several years before the discovery of the new exoplanets (Nottale 1993 , 1994), and could have been used to anticipate the possibility of this discovery.
© European Southern Observatory (ESO) 2000
Online publication: September 5, 2000