Identikit of planetary systems

The first two results had been published on A & A of the project GAPS – Global Architecture of Planetary Systems. Highly accurate measurements of the spectrometer HARPS -N, installed at the Galileo National Telescope, are helping astrophysicists to define with greater precision, important features of the hundreds, perhaps thousands, of planetary systems in our galaxy. In search of Earth-like planets and answers about the formation of our solar system.



Around what types of stars we must try planets? Are there more or those giant planets like Earth? Our solar system is a rule or an exception? Asking you these questions twenty years ago, it seemed to the limits of fiction. Today is astrophysics peak.

To try to answer these questions the project GAPS ( Global Architecture of Planetary Systems) INAF face, as the name suggests , to gain a greater understanding of the architecture of planetary systems , and structural properties of extrasolar planets and the dependencies between physical properties of the planets and stars that host them. All this in the context of the broader context on the understanding of how they form and evolve planetary systems and in particular which of the scenarios (see the board), relied so far, is the most plausible. GAPS help astronomers from ten locations INAF, including the Galileo National Telescope, the University of Padua and Milan, and other foreign institutions.

The first results of GAPS, which makes use of the spectrograph HARPS -N for which installation has been chosen the Galileo National Telescope in the Canary Islands, we confirm most of the observations and deductions made so far, which tell us that it is more likely to find planets giants orbiting stars rich in heavy elements, or high- metallicity, i.e. relatively young stars than the age of the universe.

These results, presented in a letter in Astronomy & Astrophysics, tell us that there are planets orbiting the star low in heavy elements HIP 11952. The presence of two planets had previously been bought by a group of astronomers, analyzing data obtained with a much less sophisticated instrumentation HARPS -N.

And, also from the collection and analysis of data obtained with highly accurate HARPS – N on the star-planet system called Qatar -1 , about 600 light-years away in the constellation of Cepheus and the Dragon , is always a first article in the journal A & A.

“With the data we have analyzed and published we put another small but important piece to the puzzle on the still unresolved question of the characterization of the architectural properties of extrasolar planets and their dependence on the physical properties of the host star … ” says Elvira Covino INAF of Naples, who led the study on Qatar -1. “For example, so far have not sought the terrestrial planets in systems where the giant planets have been detected. In fact, the extrasolar planets discovered so far are very different from the planets of the Solar System. Many of them have masses and sizes similar to those of Jupiter but move in orbits much closer (even a hundred times lower than the Earth-Sun distance) with orbital periods of just a few days. For Qatar -1 we were able to gather so much data and of such high quality that we can now characterize this system with great accuracy. ”

The GAPS team has combined the high-precision measurements, obtained with HARPS -N, with the photometric data and has thus been able to obtain a complete view as never before of the orbital parameters and physical properties of the Qatar -1 system. Qatar -1 contains therefore a Hot Jupiter , ie a planet with a mass equal to about 1.3 times the mass of Jupiter , more massive than stated above, which orbit on a plane very well aligned with the axis of rotation of the star and with an eccentricity anything. The host star , of which were also derived atmospheric properties , now has its own identity card states : it is , as already said , a star rich in heavier chemical elements of hydrogen and helium and also is one of the weakest around which , with ground-based observations , has ever been detected a planet. It is a dwarf of spectral type K, age comparable with that of the Sun Wheel slowly but also shows an intense activity on its surface, something that you would not expect in a star of this type. This suggests that there might just be the strong tidal interaction with the giant planet, which orbits at close range, to ensure that the chromospheric activity is so intense. And astronomers believe that a possible scenario is the one that will fall off the planet on the star to be “swallowed “.

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