Scattering stars smooth fade in galaxy brightness

摘要

All spiral galaxies have the same exponential fall-off in brightness from their centre because of the way large masses within the galaxies scatter stars, suggests new research published in Astrophysical Journal Letters. There are not just stars in spiral galaxies, but vast clouds of gas and dust too. These 'Giant Molecular Clouds', or GMCs, are the birthplaces of stars and can be enormous, up to 600 light years in diameter and up to tens of millions of times greater than the Sun's mass. As such they wield a significant gravitational influence.