For us planet — the gas giants or solid worlds, revolving in the orbit of the parent star. And as long as go the stars, the milky Way is littered with hundreds of billions of such planets, including our own, and so far the only unique Land. And each planet is, in principle, and also its own unique story of birth and life. Some of them are massive and bright, the other small and dim; some were born a few million years ago, others may compete with the age of the Universe itself. But there is one thing in common, which we endow all these planets: the solar system. As shown by the Kepler mission and other searches for exoplanets if you want to find the planet — just poke star and her surveys: around it you’ll find one, but a whole system of planets.
And yet — in addition to the stars and all bodies that revolve around them should be innumerable planets, not bound to the Central star in General: the planets-derelicts. Scientists believe that this is true for any place of the Universe, from small star clusters and interstellar space to the cores of giant galaxies. As far as we know, in the cosmos the starless planets no less than the stars themselves — maybe more. From this it follows that for each point of light you see, there is much more massive points that you don’t see because they don’t emit visible light.
Through observations, we found a number of possible candidates for wandering the planet. “Candidate” is an important word; we cannot be sure that these planets are true, since we don’t have good technique confirmation of this fact. Even with our modern equipment they are so hard to discover what we should imply the presence of many more worlds than we already have. But we’ve already found and can draw conclusions. Where are these planets?
One of the persuasive sources of all these planets near us, and we value it very much.
We know how solar systems are formed: after gravitational collapse creates a region of space in which the synthesis is lit, around the Central star is going protoplanetary disk. Gravitational perturbations regularly appear in this disc, attracting more and more matter from their surroundings, while the heat of the newly formed Central star slowly blows out the lightest gas in the interstellar medium. Over time, gravitational perturbations grow into asteroids, solid planets and gas giants.
But the fact that these worlds not only revolve around its star, but the gravitational pull of each other. Over time, these planets migrate to the most stable configuration, which can achieve: the most massive worlds take their most stable places, often sacrificing other worlds smaller. What happens to “loser” in the space of a planetary battle for an advantage? They are absorbed in the fusion process, fall on the Sun or ejected from the solar system into interstellar space.
Recent modeling has shown that for every rich planets of the solar system, like our own (gas giants) will be thrown at least one gas giant — in the interstellar medium, where it will be doomed to wander the galaxy for a wandering planet rogue. The number of the worlds smaller solid ejected from the system may reach 5-10. It is, in principle, is the largest source of the planets, the outcasts, and in our own galaxy there are probably hundreds of billions of them.
Particularly amusing that when scientists are conducting theoretical calculations, the planets ejected from young solar systems is two times less than the expected number of wandering planets. But where did they come from? To understand the origin of the majority of starless planets, we need to look wider at the same time: not only when formed our Solar system, but also the cluster of stars (and star systems), which were formed at the same time.
Star clusters are formed in the process of slow collapse of cold gas, mostly hydrogen, and as a rule, originate in the already existing galaxy. Deep in the collapsing clouds are formed by the gravitational instability and the first, most massive instability, attract more and more matter. When enough matter is collected in a small region of space and the density with the temperature in the core become high enough, nuclear fusion begins and stars are formed.
But no one is born a star and star system, and the multitude of them, as every cloud that collapses with the formation of a new star contains enough matter to form many stars. Along with this comes something. Formed the largest star is also the hottest and most blue, that is, emits the ionizing, ultraviolet radiation. And that star begins one of the most active races to take its place in the cosmos.
If you look at zvezdoobrazovaniya nebula, you can see two processes occurring simultaneously:
- Gravity tries to pull matter towards this young, growing gravity swashplates
- Radiation burns out the neutral gas and pushes it back into the interstellar medium
Who will win?
The answer depends on how you define victory. The large gravity swashplates form the large, hot and blue stars — but these stars are extremely rare. Swashplates smaller (still large) form other stars, but as you decrease the weight they are becoming more and more. That’s why, when we look deeply into the cluster of young stars, it is easy to see the bright (blue or other) stars, but they far exceed the number of yellow (and red) stars with a mass smaller.
If it weren’t for the radiation, emitted by young stars, these dull, red and yellow stars would have continued to grow and become more massive and brighter blazed stronger. Star (main sequence) there are different types, from O-stars (very hot, large and blue) to M stars (small, cold, red, low-mass). And although most of the stars — ¾ — is in the stars M-class, and less than 1% of all stars have in the stars O – or B-type, the total mass of the two latter types of stars comparable to the total mass of stars M-type. Need about 250 stars M-class to compete with the mass of the O star.
As it turned out, about 90% of the original gas and dust that were in zvezdopada nebula, blown out into the interstellar medium, and not the formation of stars. The most massive stars are formed faster and start to blow the material from the nebula. Just a couple million years of material is less, and new stars cease to form. The remaining gas with the dust completely burnt out.
And now the most interesting. Not only stars M-class — with a mass between 8% and 40% of solar — are the most common type in the Universe of stars. There is a lot more that could be stars M-class, if the stars with a large mass is not burned away excess material.
In other words, for each formed star, there are far more failed stars that never gained critical mass: and such stars can be tens to hundreds of thousands for each formed star.
Just imagine: our own Solar system contains hundreds or even thousands of objects that potentially meet the geophysical definition of a planet, astronomically but were excluded only because of their orbital position. Now imagine that for every star like our Sun, the hundreds of failed stars that never gained enough mass to start fusion in the core. This is a homeless planet or wandering of planets — far more than planets like ours orbiting stars. Planets-orphans can be with or without atmosphere, and detecting them is extremely difficult, especially the smallest. But consider this: on each planet like ours in the galaxy can be up to 100,000 planets that revolve around stars, but never rotated. Finding them is very difficult.
So, even though we may have some of the planets ejected from young solar systems, and even a handful of such worlds in the galaxy originating from the Solar system, the vast majority of all planets in the galaxy never held the stars. Planet-outcasts roam the galaxy, doomed to eternal wandering in the dark, and will never know the heat of the parent star. Their potential parents, perhaps even the stars never. In the galaxy may be a gazillion of these wandering worlds that we haven even open not really started.