Ground-Based Telescope Observes ‘Super-Earth’ 40 Light-Years Away

For the first time, a ground-based telescope has been used to observe the transit of a “super-Earth” around its parent star.

An international team of astronomers used the 2.5-m Nordic Optical Telescope on the island of La Palma, Spain, to perform differential spectrophotometry measurements of 55 Cancri e during one transit in 2013 and another this year.

“Our observations show that we can detect the transits of small planets around Sun-like stars using ground-based telescopes,” said Dr. Ernst de Mooij of Queen's University in Belfast, Northern Ireland.

Roughly 40 light-years away, 55 Cancri e is about twice as big and eight times as massive as the Earth. The inmost of five known planets in the star system, its orbit takes only 18 hours, and daytime surface temperatures reach 1700 °C.

An artist’s rendering of Earth and 55 Cancri e. Courtesy of NASA/JPL.

Discovered in 2004, 55 Cancri e until now had been studied exclusively using space-based telescopes.

The exoplanet’s transit dimmed its parent star by 0.05 percent for almost two hours, results the researchers said agreed well with previous space-based observations.

“It's remarkable what we can do by pushing the limits of existing telescopes and instruments, despite the complications posed by the Earth's own turbulent atmosphere,” said professor Dr. Ray Jayawardhana of York University in Toronto.

Scintillation noise in the data prevented the researchers from characterizing the planet’s atmosphere, but such noise could be decreased in future observations. Next, the team plans to search for water steam in the planet’s atmosphere.

The researchers said their observations demonstrate that moderate-sized ground-based telescopes will be capable of routine follow-up observations of super-Earth candidates discovered by the Transiting Exoplanet Survey Satellite (TESS), planned for launch in 2017.

The research was published in Astrophysical Journal Letters (doi: 10.1088/2041-8205/797/2/L21).

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