The detection of potentially habitable exoplanets is not the big news it once was — there have been so many identified already that the novelty has faded a bit. But that hardly means surprising and potentially breakthrough discoveries aren’t being made. They are, and one of them was just announced Monday.
This is how the European Southern Observatory, which hosts the telescope used to make the discoveries, introduced them:
Astronomers using the TRAPPIST telescope at ESO’s La Silla Observatory have discovered three planets orbiting an ultra-cool dwarf star just 40 light-years from Earth. These worlds have sizes and temperatures similar to those of Venus and Earth and are the best targets found so far for the search for life outside the Solar System. They are the first planets ever discovered around such a tiny and dim star.
A team of astronomers led by Michaël Gillon, of the Institut d’Astrophysique et Géophysique at the University of Liège in Belgium, have used the Belgian TRAPPIST telescope to observe the star, now known as TRAPPIST-1. They found that this dim and cool star faded slightly at regular intervals, indicating that several objects were passing between the star and the Earth. Detailed analysis showed that three planets with similar sizes to the Earth were present.
The discovery has much going for it — the relative closeness of the star system, the rocky nature of the planets, that they might be in habitable zones. But of special importance is that the host star is so physically small and puts out a sufficiently small amount of radiation that the planets — which orbit the star in only days — could potentially be habitable even though they’re so close. The luminosity (or power) of Trappist-1 is but 0.05 percent of what’s put out by our sun.
This is a very different kind of sun-and-exoplanet system than has generally been studied. The broad quest for an Earth-sized planet in a habitable zone has focused on stars of the size and power of our sun. But this one is 8 percent the mass of our sun — not that much larger than Jupiter.
“This really is a paradigm shift with regards to the planet population and the path towards finding life in the universe,” study co-author Emmanuël Jehin, an astronomer at the University of Liège, said in a statement.… Read more