HE 0107−5240

HE0107−5240 was found by Norbert Christlieb and colleagues at the University of Hamburg in Germany as a byproduct of the Hamburg/ESO Survey for faint quasars with the 1m ESO Schmidt telescope. Follow-up observations were made at the Siding Spring 2.3 m Telescope and high-resolution spectra were taken at the European Southern Observatory in Chile, using one of the units of the Very Large Telescope. In 2005, a second star with an even smaller iron abundance, HE 1327-2326 ([Fe/H]=-5.4), was found, also in the Hamburg/ESO survey. In 2014 an even more metal poor star was announced: SMSS J031300.36−670839.3. In 2020, HE 0107−5240 was revealed to be an spectroscopic binary system. The orbit has a period of 10,560 days (28.9 years) and a low eccentricity. The companion has a mass of at least 0.14 solar masses.