INTERVISTA A David Lafreniere Scienziato dell’università di Toronto sul NUOVO PIANETA SCOPERTO

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Fotografato un nuovo pianeta exstra solare. La notiza è di pochi giorni data dall’Universita d Toronto, noi di Italoeuropeo abbiamo intervistato il Dr. David Lafreniere che insieme al prof Ray Jayawardhana hanno scoperto il pianeta…. ( di Filippo Baglini-Londra)

Questa non è fantascienza ma pura realtà, una realtà exstrasolare. grazei a una’indagine che riguarda 85 stelle analizzate dal Gemini North Telescope alle Hawaii gliscienziati dell’università di Tornto hanno fatto la prima foto di un pianeta extrasolare avvistato intorno a una stella, più piccola, ma simile al Sole. Quello che ha stupito gliscienziati,  è stata la distanza che c’è tra questo nuovo pianeta e la sua stella che è di circa 330 unità astronomiche UA (un’unità astronomica, corrisponde alla distanza Terra-Sole che è di 150 milioni di chilometri).

Per saperne di più su questo interessante scoperta abbiamo intervistato uno degli scienziati che ha contribuito alla scoperta il Dr. David Lafreniere :


How you have acknowledged the planet? Were you looking for it? 

We used the adaptive optics system of the Gemini North telescope to image several stars in a young star-forming region. Adaptive optics technology allows to ‘undo’ the blurring effect of the atmosphere on the star light, and thus enables to get sharper images of stars, which in turn makes it easier to see faint objects next to them. The goal of our observations was to discover new stellar, brown dwarf or planetary mass companions to our target stars. The image of the star 1RXS J160929.1-210524 that we obtained in this manner showed a faint source close to it, and we then obtained additional observations to determine the exact nature of this faint source, and eventually found it was a planetary mass object.


 How could be formed? How much is it distant from the Earth?    

The traditional formation mechanism for giant planets is called core accretion, in which a small planet seed gradually grows by accreting solid particles from the circumstellar disk until this core becomes massive enough to capture large amounts of gas from the disk, at which point it becomes a giant planet. The time required for this process to work is strongly sensitive to the density of solid material in the circumstellar disk, the less material available the longer it takes. At hundreds of astronomical units from the star, the density of material in the disk is so low that any small seed of planet would not be able to grow enough before the disk vanishes (after a few million years). So if this planet formed through this mechanism, it would have had to form at a small distance and then migrate outward to its current separation. Outward migration can result from gravitational interaction between multiple planets, i.e. the gravitational effects of the planets on each other modify their orbits, gradually sending one planet on a larger orbit, or from interaction of the planet with the circumstellar disk.

Another possibility is that the planet formed directly at its current location but through a different mechanism. Maybe it formed as binary stars do, by the direct collapse and fragmentation of a molecular cloud core, or maybe it formed by the rapid gravitational collapse of a part of the circumstellar disk. All possibilities present their share of difficulties though, and it is hard to determine which one is more likely.

Both the star and the planetary mass objects are located about 500 light years away from the Earth.

     
what the greatest surprise has been on this planet and because? 

The most surprising thing about this planet, if it is confirmed to be bound to the star, is its large separation of 330 times the Earth-Sun distance. This is surprising because it is much larger than the separation of the most distant planet in our solar system and those of all other planets discovered by indirect methods. Currently, the theories of planet formation have difficulties explaining how planets could exist at such large separations.


This planet is really the first photographed out of the solar system? and the planet photographed in 2005? 

Yes this new object is the first which both has a planetary mass and is found around a normal star. About the 2005 discovery you’re referring to, is it the object orbiting the star GQ Lup? If so, the mass of this object has been recently determined to be about 15 times the mass of Jupiter, so formally it is a brown dwarf rather than a planet (see the planet definition at http://www.dtm.ciw.edu/boss/definition.html). If you were thinking of the companion to 2M1207, in this case the companion indeed has a planetary mass but the primary is a brown dwarf and not a star.


For the people that are not of the work: what importance is to have discovered a new weepings out of the solar system?  

This new discovery showcases the large diversity of planets that exist around sunlike stars: some exist at separations much smaller than the separations found in our solar systems and some seem to exist at separations much larger than found in our solar system. The discovery and study of new planets will ultimately allow us to understand exactly how planets form around sunlike stars.

thanks Dr.David Lafreniere  I hope to speak you soon about other news
  sure  thanks  Baglini  .