Image: An artist’s impression of HD 40307 g. Credit: University of Hertfordshire.

Possible Habitable World
in a Six-Planet System


At 42 light years from Earth, the star HD 40307 is reasonably within the Sun’s neighborhood, so the news of a potentially habitable planet there catches the eye. HD 40307 is a K-class dwarf, one previously known to be orbited by three super-Earths — with masses between the Earth and Neptune — that are too close to the star to support liquid water on the surface. Now we have the discovery, announced in a new paper in Astronomy & Astrophysics, of three more super-Earth candidates found by digging into data from HARPS (the High Accuracy Radial Velocity Planet Searcher) and HIRES (the High Resolution Echelle Spectrograph).

Mikko Tuomi (University of Hertfordshire) and team put a new software tool called HARPS-TERRA to work on the archival data that allowed them greater precision in filtering out false positives from stellar activity. Says Tuomi:

“We pioneered new data analysis techniques including the use of the wavelength as a filter to reduce the influence of activity on the signal from this star. This significantly increased our sensitivity and enabled us to reveal three new super-Earth planets around the star known as HD 40307, making it into a six-planet system.”

Read more: Possible Habitable World in a Six-Planet System — Centauri Dreams.

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