Three Possibly Habitable Planets Found Near Ultracool Dwarf Star
Astronomers have discovered three planets orbiting an ultracool dwarf star just 40 light-years from Earth. These worlds have sizes and temperatures similar to those of Venus and Earth and are said to be the best targets for the search for life outside the solar system.
A team of astronomers led by Michaël Gillon, of the Institut d'Astrophysique et Géophysique at the University of Liège in Belgium used the Belgian TRAPPIST telescope to observe the star 2MASS J23062928-0502285, now also known as TRAPPIST-1, eso.org has said. They discovered that this murky and cool star slightly faded at regular intervals, showing that several objects were passing between the star and the Earth. After a detailed examination, experts found that three planets with similar sizes to the Earth were present.
Co-author of the new study, Emmanuël Jehin showed his excitement by saying that this really a shift in paradigm regarding planet population and the path that will lead to finding life in the Universe. "So far, the existence of such 'red worlds' orbiting ultra-cool dwarf stars was purely theoretical, but now we have not just one lonely planet around such a faint red star but a complete system of three planets," he continued.
According to Science Daily, lead author of the study, Michaël Gillon explained the findings saying, "Why are we trying to detect Earth-like planets around the smallest and coolest stars in the solar neighborhood? The reason is simple: systems around these tiny stars are the only places where we can detect life on an Earth-sized exoplanet with our current technology. He added saying that if experts want to find life in other parts of the Universe, they should start with these dwarf planets.
TRAPPIST-1 is an ultracool dwarf star - it is much cooler and redder than the Sun and barely larger than Jupiter. These stars can commonly be found in the Milky Way and very long-lived. However, this is the first time that planets were found around one of them. Even though it can be found close to Earth, this star is not too bright and too red to been with the naked eye or even with the use of a large telescope. This star lies in the constellation of Aquarius (The Water Carrier).
Astronomers will search for further signs of life by studying the effect of the atmosphere of a transiting planet has on the light reaching the Earth. For normal Earth-sized planets orbiting most stars, this small effect is flooded by the bright starlight. However, for the case of faint red ultra-cool dwarf stars, like TRAPPIST-1, this may not be big enough to be detected.
Follow-up observations with larger telescopes, including the HAWK-I instrument on ESO's 8-metre Very Large Telescope in Chile showed that planets orbiting TRAPPIST-1 are of the same size as the Earth. Two of the planets were found to have orbital periods of about 1.5 days and 2.4 days, while the third planet's orbital period estimated between 4.5 to 73 days.
"With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun. The structure of this planetary system is much more similar in scale to the system of Jupiter's moons than to that of the Solar System," explains Michaël Gillon.