Two potentially habitable planets detected orbiting the nearest Sun-like star
A new study by an international team of astronomers, led by the University of Hertfordshire, reveals that tau Ceti, the nearest Sun-like star (about 12 light years away from the Sun), has four Earth-sized planets orbiting it – two of which could be habitable.
These four planets have masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around the nearest Sun-like stars. Two of them are super-Earths located in the habitable zone of the star and thus could support liquid surface water.
These planets are detected by observing the wobbles in the movement of tau Ceti. The newly discovered planets correspond to detecting variations in the movement of the star as low as 30 cm/s, whilst 10 cm/s is the upper limit required for detecting an Earth analog - a planet or moon with environmental conditions similar to those found on the planet Earth.
Milestone in the search for Earth analogs
Dr Fabo Feng, research fellow at the University of Hertfordshire and lead researcher on the study, said: ‘We’re getting tantalisingly close to observing the correct limits required for detecting Earth-like planets. Our detection of such weak wobbles is a milestone in the search for Earth analogs and the understanding of the Earth’s habitability through comparison with these.’
Four Earth-sized planets detected orbiting the nearest sun-like star
A new study by an international team of astronomers reveals that four Earth-sized planets orbit the nearest sun-like star, tau Ceti, which is about 12 light years away and visible to the naked eye. These planets have masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around nearby sun-like stars. Two of them are super-Earths located in the habitable zone of the star, meaning they could support liquid surface water.
The planets were detected by observing the wobbles in the movement of tau Ceti. This required techniques sensitive enough to detect variations in the movement of the star as small as 30 centimeters per second.
"We are now finally crossing a threshold where, through very sophisticated modeling of large combined data sets from multiple independent observers, we can disentangle the noise due to stellar surface activity from the very tiny signals generated by the gravitational tugs from Earth-sized orbiting planets," said coauthor Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz.
[...] The data were obtained by using the HARPS spectrograph (European Southern Observatory, Chile) and Keck-HIRES (W. M. Keck Observatory, Mauna Kea, Hawaii).
A paper on the new findings was accepted for publication in the Astronomical Journal and is available online. In addition to Vogt, Feng, and Tuomi, coauthors include Hugh Jones of the University of Hertfordshire, UK; John Barnes of the Open University, UK; Guillem Anglada-Escude of Queen Mary University of London; and Paul Butler of the Carnegie Institute of Washington.
Color difference makes a difference: four planet candidates around tau Ceti
Fabo Feng, Mikko Tuomi, Hugh R.A. Jones, John Barnes, Guillem Anglada-Escude, Steven S. Vogt, R. Paul Butler