The binary star system and its asteroid belt help us learn more about planet formation
Our solar system has only one star, but that’s not always true for all planetary systems. According to some estimates, it is debated that more than half of the stars could be binary, however, the exact percentages are not known. If binary systems exist, the next question is: how do planets form in such systems? Let’s take a look at the views that exist for this question.
Binary star system
The most common opinion is that planets form in disks that exist around a young star. These protoplanetary disks exist around single stars but it is still widely debated whether such disks in binary stars or not. Debris disks exist around young stars, but we don’t know if these disks are stable long enough for planets to actually form. It is possible that gravitational interactions between orbiting stars make the surrounding region unstable and hostile.
The exoplanets that have been discovered so far around binary stars are large Jupiter-like planets. They must have formed in the outer icy regions of the system, but what about Earth-like planets? A recently observed binary system, SDSS 1557, suggests that it is very possible that these planets formed closer to stars where orbits may be unstable.
The structure and formation and the asteroid belt
This system consists of a white dwarf which has a mass similar to that of the sun and a brown dwarf which orbits around the former dwarf. The brown dwarf has a mass 60 times greater than that of Jupiter. It has been observed that a rocky asteroid belt exists around the system. So what’s so interesting about it? Well, it’s important for two main reasons. The main star is a white dwarf which shows that the system is old. Our Sun will also become a white dwarf when it reaches the end of its life of about 5 billion years. It is therefore possible that the asteroid belt surrounding this binary system has been stable for some time. The second important point is that the asteroid belt is rocky and rich in metals. It is therefore very possible that these form planets very similar in composition and mass to Earth.
This doesn’t really mean that the system has rocky planets. In our own belt, no planets have formed due to Jupiter’s gravitational pull. It is possible that a similar gravitational pull occurred near SDSS 1557. The only important thing this discovery tells us is that there is a huge possibility that Earth-like planets could exist in two-star systems.