Wolf 1061

Wolf 1061 is a dim M-class red dwarf in Ophiuchus, first catalogued by astronomer Max Wolf in the early twentieth century. At magnitude 10.1 it sits well below naked-eye visibility, but at just 14 light-years it is one of the Sun's close neighbours — the 36th-closest known stellar system. It is a slow, magnetically quiet old star, probably several billion years in age.

In December 2015 a team from the University of New South Wales announced the discovery of three planets orbiting Wolf 1061, detected with the HARPS spectrograph at ESO's 3.6-metre telescope in Chile. Wolf 1061 b (at least 1.9 Earth masses) orbits inside the habitable zone every 4.9 days. Wolf 1061 c (at least 3.4 Earth masses) sits near the inner edge of the habitable zone with a 17.9-day orbit. Wolf 1061 d (at least 7.7 Earth masses) orbits just beyond the outer edge of the habitable zone in 217 days. Wolf 1061 c in particular attracted attention as one of the closest potentially habitable super-Earths known.

Follow-up studies showed that Wolf 1061 c's orbit varies on timescales of tens of thousands of years, which could modulate its climate similarly to Milankovitch cycles on Earth. Unlike many M-dwarfs, Wolf 1061 appears relatively inactive in ultraviolet, which is promising for atmospheric retention on its planets. At 0.011 solar luminosities, the star's habitable zone hugs it closely — all three planets orbit well within the distance Earth keeps from the Sun.