HIP 57050, also known as GJ 1148, is a red dwarf star from the Sun with two known planetary companions. Other designations for this star include LHS 2443, G 122-40, and Ross 1003.
HIP 57050 has a metallicity twice that of the Sun and is among the highest in the immediate solar neighborhood.
Planetary system
A team led by astronomer Nader Haghighipour reported the discovery of a Saturn-mass planet in the habitable zone of the star in 2010. According to Haghighipour, the detection is important because it "indicates that observational techniques are on the right track for finding habitable low-mass rocky planets similar to Earth."
According to its discoverers, HIP 57050 b provides support for the proposition that planet-bearing M-class stars tend to be metal-rich, a correlation already observed in F, G and K-class stars.
At the expected planetary effective temperature, the atmosphere may contain water clouds, potentially detectable by the Hubble Space Telescope if it could capture a planetary transit.
The planet's discoverers speculated about the possibility of a habitable exomoon:
Paul Gilster of the Tau Zero Foundation has commented:
Gilster suggested that an Earth-sized moon could exist around the planet if it were captured after forming independently.
A second planet was suspected based on additional radial velocity measurements made at W. M. Keck Observatory, and this was confirmed by measurements taken at Calar Alto Observatory in 2017.