ROBOT telescope discovers ENORMOUS planetary neighbours

If robots can find planets, why can't they find the ingredients to get me a G&T?

Night sky over Hawaii

A robotic telescope enslaved by the will of astroboffins has done their bidding and discovered three "supersized Earths" orbiting a star in our galactic neighbourhood. Based at Lick Observatory, the robotic telescope scans the sky every night in search of new Earth-like planets for colonisation study.

In a freely available paper titled Three super-Earths orbiting HD 7924 and published in the Astrophysical Journal, a team of star-gazing professionals discovered a planetary system orbiting a nearby star in our galactic neighbourhood – a mere 54 light-years away.

The three planets orbit their star at a distance closer than Mercury orbits the Sun, completing their orbits in the frightening speeds of 5, 15 and 24 days, which made them extremely difficult to detect.

"The three planets are unlike anything in our solar system, with masses seven to eight times the mass of Earth and orbits very close to their host star," said UC Berkeley graduate student Lauren Weiss.

Weiss is the leader of the UC Berkeley component of the team that discovered the planets, using the Automated Planet Finder (APF), a fully robotic 2.4-meter optical telescope at Lick Observatory, which is situated on the summit of Mount Hamilton, near San Jose, California.

To date, most of the planets discovered outside of our solar system have been the size of Neptune — 17 times the mass of Earth — or larger, with the majority being gas giants like Jupiter, which are several hundred times the mass of Earth. They are usually big enough, and far enough away from their stars, to be noticeable without sophisticated technological assistance.

The goal of the APF, however, is to find small planets around the nearest stars, in the hope that some of them may have temperatures and surface conditions suitable for life.

"The discovery demonstrates the APF’s ability to find low-mass planets around nearby stars," Weiss said. "Robotic telescopes are going to be the way we find planets in the future."

As the planets are invisible to the naked eye, their existence was only betrayed by the tremulous wobble they created in their host star. This can be detected by a Doppler technique pioneered by Weiss’s adviser, Geoffrey Marcy.

The team detected the wobble of the star "HD 7924" as the planets orbited and pulled on it through gravitation. APF and Keck Observatory traced out the planets' orbits over many years using the Doppler technique, while APF made crucial measurements of the brightness of "HD 7924" to assure the validity of the planet discoveries.

The APF facility offers a huge boost to planetary discovery times. Planets will be discovered and their orbits traced much more quickly because APF is a dedicated facility that robotically searches for planets every clear night. Training computers to run the observatory all night, without human oversight, took years of effort by the University of California Observatories staff and graduate students on the discovery team.

"We initially used APF like a regular telescope, staying up all night searching star to star. But the idea of letting a computer take the graveyard shift was more appealing after months of little sleep. So we wrote software to replace ourselves with a robot," said University of Hawaii graduate student BJ Fulton. ®

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