Astronomers detect 11 new planets
Swiss astronomers, working as part of an international team, have announced the discovery of 11 new planets orbiting around stars similar to our sun, including two new planetary systems.
The scientists say the moons of one of these extra-solar planets or exoplanets could theoretically support life.
Swiss astronomers from the Geneva Observatory are working in collaboration with research institutes in France, Israel and the United States.
Most of the new discoveries were made by the Swiss at La Silla observatory in Chile and by a Swiss-French team at the Haute-Provence Observatory in France.
The team are particularly excited by the movement of one exoplanet around its sun-like central star. The orbit is nearly circular and with a period of 385 days, its distance from the star of 150 million kilometres, is almost equal to the distance between the sun and the earth.
“The temperature at this distance from the star is relatively mild like we have on earth so we are dreaming of the possibility of life on this system,” said Michel Mayor, director of the Geneva Observatory.
“The planet itself is a giant, gaseous planet unsuitable for life but we know that in the solar system, every big planet like Jupiter and Saturn has many moons so perhaps it’s possible that the moons around this new planet are suitable for the development of life.”
The exoplanets were observed indirectly – their presence detected by changes in the velocity of their central stars.
“What we measure is the reaction movement of a star, caused by a planet orbiting around it,” said Francesco Pepe, a member of the Geneva team. “With a spectograph, we measure this movement of the star and can deduce whether there is a planet or not.”
Scientists are not only able to deduce the planet’s orbit but also its minimum mass. They believe the masses of these new objects are about 10 times the mass of the planet, Jupiter. Astronomers have now identified six stars with multiple planets.
Many questions remain unanswered about the formation and evolution of extra-solar planets. Mayer said the latest discoveries pave the way for further investigation.
“All this is preparation for the future. We have a lot of new space missions designed to observe and to measure extra-solar planets but they need to know in advance what are the most suitable targets.”
Swiss astronomers are particularly active in the Coralie search programme at La Silla and the Elodie project in southern France.
Between them, these two programmes have been responsible for the discovery of half of the known extra-solar planets.
by Vincent Landon
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