Lacaille gave eleven stars in the constellation Bayer designations, using the Greek alphabetto label them Alpha through to Lambda Mensae (excluding Kappa). Gould later added Kappa, Mu, Nu, Xi and Pi Mensae. Stars as dim as these were not generally given designations; however, Gould felt their closeness to the South Celestial Pole warranted their naming.Alpha Mensae is the brightest star with a barely visible apparent magnitude of 5.09, making it the only constellation with no star above magnitude 5.0. Overall, there are 22 stars within the constellation's borders brighter than or equal to apparent magnitude 6.5.[b]
Gamma Mensae is the second-brightest star in the constellation, at magnitude 5.19. Located 104.9 ± 0.5 light-years from Earth, it is an ageing (10.6 billion year-old) star around 1.04 times as massive as the Sun. It has swollen to around 5 times the solar radius, becoming an orange giant of spectral type K2III.
Beta Mensae is slightly fainter at magnitude 5.31. Located 660 ± 10 light-years from Earth, it is a yellow giant of spectral type G8III, around 3.6 times as massive and 513 times as luminous as the Sun. It is 270 million years old, and lies in front of the Large Magellanic Cloud.
Zeta and Eta Mensae have infrared excesses suggesting they too have circumstellar disks of dust. Zeta Mensae is an ageing white giant of spectral type A5 III around 394 ± 4 light-years from Earth, and Eta Mensae is an orange giant of spectral type K4 III, lying 650 ± 10 light-years away from Earth.
Pi Mensae is a solar-type (G1) star 59.62 ± 0.07 light-years distant. In 2001, a substellar companion was discovered in an eccentricorbit. Incorporating more accurate Hipparcos data yields a mass range for the companion to be anywhere from 10.27 to 29.9 times that of Jupiter. This confirms its substellar nature with the upper limit of mass putting it in the brown dwarf range. The discovery of a second substellar companion—a Super-Earth—was announced on 16 September 2018. It takes 6.27 days to complete its orbit and is the first exoplanet detected by the Transiting Exoplanet Survey Satellite (TESS) submitted for publication.
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