2M1207b was discovered orbiting the brown dwarf 2M1207.
The planetary-mass companion was first identified in 2004 using infrared observations from the European Southern Observatory’s Very Large Telescope at Paranal Observatory in Chile. It became famous as one of the first objects to be directly imaged while orbiting a body outside the Solar System.
2M1207b is estimated to have roughly five to six Jupiter masses and lies at a projected distance of about 40 astronomical units from its brown-dwarf primary—comparable to Pluto’s average distance from the Sun. It is young, hot, and still glowing from heat left over from its formation and gravitational contraction.
There is an important classification caveat. Because its mass is relatively large compared with the brown dwarf, and because it may have formed by gravitational collapse rather than disk accretion, some astronomers call it a planetary-mass companion or sub-brown dwarf rather than a conventional exoplanet. Nevertheless, “2M1207b” is the canonical answer to this quiz question.