The Cosmic ‘Bubble Factory’ Mystery. We don’t know what caused the bubbles and arcs in NGC 2359, but the main culprit is the massive Wolf-Rayet star in the center of one of the bubbles - visible slightly below and to the right of the center. Wolf-Rayet stars are massive, highly luminous stars that continually shed material in a stellar wind - which commonly form bubbles in the interstellar medium. But the unusual structure of the NGC 2359 arcs indicate something more complex is going on. Experts wonder if the star is moving supersonically? Or, is there another energetic star in the vicinity?