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51 Pegasi

Proper NameHelvetios
Bayer DesignationNone
Flamsteed Number51 Pegasi
HR (BSC)8729
Right Ascension22h 57m 28s
Declination+20° 46' 8"
Distance50 light years
15 parsecs
MagnitudeApparent: +5.4
Absolute: +4.5
Spectral ClassG2IV yellow subgiant
Planets in this systemDimidium (Helvetios b), gas giant
Optimum VisibilitySeptember
NotesThis faint fifth-magnitude star off the western edge of the Square of Pegasus is important as the first typical star to be found to possess a planet. Two planets had previously been detected in orbit around the pulsar now known as Lich, but in 1992, 51 Pegasi's lone planet was the first to be discovered orbiting a relatively Sun-like star.

Imagery provided by Aladin sky atlas

Image of 51 Pegasi b

Possible appearance of a large gas giant in the Helvetios system, designated Dimidium or 51 Pegasi b, shown here with two hypothetical moons.

A yellow dwarf similar in size and structure to the Earth's own Sun, and some fifty light years from the Solar System. Helvetios (also known by its Flamsteed designation of 51 Pegasi) is important as possessing a planetary system.


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