Seven planets have been newly discovered outside our solar system by an international team that included an astrophysicist from Tel Aviv University, thanks to the French CoRoT space telescope, it was announced on Monday.
Prof. Tsvi Mazeh of TAU’s Physics and Astronomy School was the only Israeli on the team that discovered the planets, which were detectable by the small black spots visible on the surfaces of their respective suns as the planets passed in front of them.
The CoRoT space telescope (its name abbreviates convection, rotation and planetary transits) was launched 1,265 days ago – on December 27, 2006 – by the National Space Studies Center in France and CNRS French laboratories, along with several international partners in Europe, plus Israel and Brazil. The spacecraft, belonging to the Proteus series, is equipped with a focal telescope 27 centimeters in diameter and a camera sensitive to tiny variations of the light intensity from stars.
Using a method called stellar seismology to probe the inner structure of the stars, it can also detect extrasolar planets by observing the periodic micro-eclipses occurring when these bodies transit in front of their parent star.
The telescope’s observation periods last for five months at a time, making it possible to carry out this pioneer mission in the discovery of telluric extrasolar planets – bodies with properties comparable to those of the rocky planets of our solar system.
In the last two years, the CoRoT has been measuring with great exactitude the power of light from thousands of suns that seem to us to be distant stars in the night sky. The international team operating the space telescope managed to detect slight reductions in the power of the light of a small number of suns, caused by their planets passing in front of them and creating tiny shadows.
The “new” planets join eight others that were previously discovered by the CoRoT team. In each of the cases, observations from Earth were needed to complete the data and confirm that in fact planets had been indirectly observed, and to determine their size. These observation points are in TAU’s observatory in Mitzpe Ramon, in the Canary Islands, in Chile and in Hawaii.
Even though the suns and planets are so distant, the observations
succeeded in estimating their size, mass and density. Six of the seven
could be defined as planets by their mass, while the seventh planet is
slightly heavier and is described as a “brown dwarf.”
Mazeh noted Monday that each planet was different.
“Each planet is an additional piece of information for solving the
riddle of the creation and development of planets,” added Dr. Magali
Delcuil of Marseilles. “The more planets we discover, the better we
will be able to understand the processes involved.”
Among the newly discovered celestial bodies is CoRoT-8, the smallest
planet in the group. The team believes its structure is similar to
Uranus and Neptune in our solar system, which are made of ice.
CoRoT-10b has an especially long orbit because it comes closer to and
then moves further from its sun. As such, the amount of light and heat
that reaches it differs by a multiple of 10. CoRoT-15 has a mass 60
times bigger than that of Jupiter, our largest planet. Brown dwarfs
like #15 are rare, so they provide much information, said Mazeh.
Each newly discovered planet is a “new world about which we had no idea
before the CoRoT observations,” the TAU scientist concluded. “We are
like Columbus, who sailed his ships beyond the horizon to worlds that
excited the imagination. But unlike Columbus, who found countries whose
nature and weather were similar to what he left behind, in our case the
planets are so different and so distant. Surprises beyond our
telescopes can rise above our imaginations.”