An international team of astronomers announced on Nov. 7 its groundbreaking discovery of a super-Earth planet in a nearby solar system that could possibly support liquid water and even life.
The research team, led by Mikko Tuomi of the University of Hertfordshire, England, and Guillem Anglada-Escudé of the University of Göttingen, Germany, said the planet’s orbital distance from its host star was similar to the Earth’s distance from the sun, thus creating a temperature that could be ideal for living organisms.
UC Santa Cruz astronomers Steve Vogt and Eugenio Rivera re-analyzed data from the European Southern Observatory (ESO) public archive and provided their measurements to the team of scientists. The data was used to produce a research paper, which has been accepted for publishing in the journal, Astronomy & Astrophysics.
“The significance of the paper was that it introduced new techniques to the field of science that can now be used to discover other similar Earth-like planets,” Rivera said.
The newly discovered planet, designated HD 40307-g, is seven times the mass of Earth. It is located in the outermost orbit of a six-planet solar system, which lies 42 light years away. The other five planets in the orbit are too close to the parent star, where the scorching heat precludes any form of life, according to the research paper. However, the super-Earth’s prime location places it in the so-called habitable zone — the distance from the star that is not too hot or too cold — suggesting that it might be conducive to an Earth-like environment.
“We suspect the planet has a longitudinal range of [ecosystems], so every creature can find a place where it’s most happy, and it would be stable for billions of years,” Vogt said.
The research paper documenting the discovery has drawn praise from scientists around the world, though many experts in the field eyed the results with caution. It was difficult for researchers to conclude whether the planet was gassy like Jupiter or rocky like Mars, or whether it had a thick or thin atmosphere. Geoff Marcy, a UC Berkeley astronomer, told the Los Angeles Times that the findings of the research paper remained speculative.
“The exquisitely high-quality data required to find an Earth-like planet doesn’t just happen by chance,” he said.
Rivera said the details surrounding the recent discovery were still very complicated, and the research team would need more data in order to verify its findings.
“The hope is that the advancement of scientific equipment will enable us in the future to make space missions to learn more about this planet, as well as discover other planets that are similar,” Rivera said.
In 2011 NASA discovered planet Kepler 22b, which had Earth-like qualities similar to HD 40307-g. But Kepler-22b is said to be 600 million light years away from Earth, significantly further than the new exoplanet’s 42 light years.
Vogt said he preferred studying reasonably nearby planets because it increased the chances of communication with intelligent life on other planets.
“The average human life is 70–80 years … so by focusing on planets within 40 light years away, you could potentially have a two-way conversation within one human lifetime,” Vogt said.
Scientists often struggle to retrieve clear signals from outer space due to planetary activity like spots, flares and fluctuating brightness levels, all of which create a noisy, muffling effect, Vogt said. However, Vogt and his colleagues developed an extremely precise reduction routine, enabling them to filter out most of the noise from the new planet’s solar system during their re-analysis of the ESO public archive data. In 2008, the data showed three planets, but by re-analyzing it with the new technique, researchers were able to find three more, including the new planet in the habitable zone.
“It’s like trying to hear a single voice in a noisy crowd. If you can find ways of turning down the crowd noise, you can hear the individual a little better,” Vogt said.
Until recently, the detection capabilities of scientific equipment were not sensitive enough to find planets the size of the recently discovered super-Earth, said UCSC astronomy graduate Jennifer Burt.
“I think [the discovery] is really encouraging,” she said. “It’s definitely a sign that we are improving our ability to detect Earth-like planets in ways that are quicker and more effective than in the past.”