Hid­den mass

How It Works - - SPACE -

One is­sue with mea­sur­ing the mass of gal­ax­ies is the gal­axy ro­ta­tion curve prob­lem. When an ice skater pulls in their arms dur­ing a spin, you would ex­pect them to move faster as their mass is more con­cen­trated to­wards their cen­tre. So in a gal­axy, you’d also ex­pect the stars nearer the cen­tre to move faster, but that’s not the case. In­stead we find that stars to­wards the edge of a ro­tat­ing gal­axy ac­tu­ally move faster, not slower. Sci­en­tists think the an­swer is the pres­ence of in­vis­i­ble dark mat­ter. The grav­i­ta­tional tug of dark mat­ter causes the stars at the edge to move faster than the­ory pre­dicts and thereby helps iron out any dis­crep­an­cies in the mea­sure­ment of a gal­axy’s grav­ity and mass.

Dark mat­ter is thought to af­fect the ro­ta­tion rate of gal­ax­ies

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.