module de distance

CONT: [...] si la magnitude absolue [M] est définie par d'autres considérations quelconques, en connaissant la magnitude apparente [m], il est facile de trouver la distance [r] exprimée en parsecs, en appliquant la condition log r = 1 + 0,2 (m-M). La quantité (m-M) s'appelle «module de distance».

CONT: The difference m-M [apparent magnitude minus absolute magnitude] ... depends only on the distance of the star and is called its ""distance modulus"". The distance Modulus of a star, then, is a measure of its distance, from which the actual distance, in parsecs, can be calculated.