The individual stars of this binary system were distinguished for the first time when the Hubble Space Telescope's Faint Object Camera recorded this image in June 1994. On the right, the fainter Gliese 623b is 60,000 times less luminous than the Sun and approximately 10 times less massive. The fuzzy rings around its brighter companion, Gliese 623a, are image artifacts. The lowest mass stars are classified as red dwarf stars , but even red dwarfs are massive enough to trigger hydrogen fusion in their cores to sustain their feeble starlight. Slightly less massive objects, known as brown dwarfs , can shine only briefly as their central temperatures are too low to utilize hydrogen as nuclear fuel.
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