Title: The Universe, Sung in Stars
Author: Kat Howard
Published in: Lightspeed Magazine, April 2015 (Issue 59)
Description, from Lois Tilton [Locus]: "The music of the spheres. A fantasy in which newborn pocket universes need to learn to sing in harmony, so they’re assigned guardians until they can sing on their own. Vera has a knack for stellar nurturing, so she adopts a baby universe, but she refuses to give up the waning white dwarf she’s been harboring, even when her mentor warns it will alter the newborn universe’s song."