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According to experts, exoplanets can be surprisingly common in our galaxy the milky way, but their number is likely higher than the number of stars. According to the calculations of astronomers, on average, each star has around him 1,6 planets, given that according to current estimates in the milky way there are about 100 billion stars, we can say that in our galaxy there are 160 billion planets.
A significant number of these planets is a small solid cosmic body, similar in size and physical properties to the Ground. The exact number of small planets while it is impossible to establish, but it is obvious that their number exceeds the number of so-called gas giants.
"This study in the greater degree is statistical in nature, but on the basis of all astronomical research conducted over the past few years, we can say that the planets around the stars of the milky way are increasingly the norm, not the exception," says study author Arno kassan from the Paris Institute of astrophysics. "Recently we have to realize our galaxy, not only as a place with billions of stars, but also a place with a huge number of planets, many of whom from us while hidden," he says.
To date, the number of confirmed exoplanets are about 700 objects, located outside the Solar system. Approximately 2 300 is the so - called "candidate planets". A large part of detectable today exoplanets detected in one of two ways: transit photometry or radial velocity.
For example, modern orbital telescope Kepler uses the first method, and it allows you to find large exoplanets, located in close proximity to their stars. The second method is more complicated, as it is based on the gravitational deviations of the stars and large planets, but it allows you to find much smaller planets farther removed from the stars. Scientists say that both ways of productive.
Kassan says that now in respect of exoplanets worked out and another technique - gravitational microlensing, which was previously developed for the study of distant galaxies. Summing up three methods for detecting exoplanets, in the next 10-15 years can be opened tens of thousands of exoplanets, scientists predict.
Extrapolating existing data for the entire milky way galaxy, French scientists claim that approximately one-sixth of the stars in our galaxy is near a so-called hot Jupiter, about half the planet like Neptune, and about 75% of the planet, conventionally referred to as "super-Earth". However, experts say that their study takes into account only the range of 0.5-10 astronomical units from the star as the inhabited territory."
"We can say that the planet low mass, such as "super-Earth" and the Neptune-like planet is significantly more widespread than giant planets such as Saturn or Jupiter," says kassan.
Based on current data, the astronomers say on average in the range from 0.5 to 10 AU star in the milky way has a 1.6 planets, that is just our galaxy according to conservative estimates, there are about 160 billion planets. "The real number of planets, probably a bit higher, as some stars have planets at a distance closer than 0.5 AU, and others - on 10 AU," says kassan.