... Lava Fountain on Jupiter's Io . ... Accretion Disk Binary System . ... Our Sun is unusual in that it is alone - most stars occur in multiple or binary systems. In a binary system, the higher mass star will evolve faster and will eventually become a compact object - either a white dwarf star, a neutron star, or black hole. Irregular Galaxy Sextans A . ... But small irregular galaxies form stars too, like this lovely, gumdrop-shaped galaxy, Sextans A. Hot Gas In Hydra A . ...