After a somewhat long wait, astronomers have discovered another solar system of 6 planets, only 100 light years distant, and orbiting a nearby sun-like star. The new planets were described in a paper published Wednesday the journal Nature and could provide a breakthrough in the understanding of how planets form. This particular system is intriguing for a number of reasons, including:
1) They display resonant orbits. Hence, the six planets have been in a stable, predictable, two-by-three orbital pattern since they were formed at least 4 billion years ago. In this case, for every three rotations around HD 110067 completed by the innermost planet, the second-closest planet completes two. The same pattern exists between the second and third and third and fourth planets, while a ratio of four-orbits to three-orbits exists between the fourth and fifth and fifth and sixth planets.
2) The resonant orbits of these planets are consistent with the idea that this system has been free of any major disturbance — say, a catastrophic impact, or the close passage of another star — for billions of years. (Observations suggest 1 in 100 systems or so have retained their resonance through the present day.)
3) The 6 planets are all hot, gaseous and unlikely to be pleasant places to visit.
According to Rafael Luque, a University of Chicago astrophysicist and lead author of the research, the chain of orbital relationships gives clues about the system’s past. Typically, central stars and their planets are born at the same time out of a cloud of gas and cosmic dust that starts to flatten into a disk shape under forces of gravitational attraction. Most of the gas migrates to the center, where the central star forms, while embryonic planets form on the disk’s outskirts from dust. When they first form, those worlds tend to be in resonance to help keep the system gravitationally stable.
In respect of (3) the 6 planets' orbits around the parent star put them well inside
what astrobiologists consider the “habitable zone” of a planetary system. Hence, they are no place for colonization, even if humans had a star gate or hyper-velocity craft to get there.
The new
paper, authored by more than 150 scientists from 12 nations, describes the
planetary system of HD 110067, a
star in our galaxy. Located in the Coma Berenices constellation, it is not visible with the naked eye.
Still, it’s only 100 light-years away, which means it is in our neighborhood, basically a suburb of the Milky Way galaxy. That proximity to Earth makes it bright compared to many other stars previously known to have planetary systems. It is 10,000 times brighter, for example, than Trappist 1, a red dwarf star that also has an intriguing swarm of rocky planets. See e.g.
The resonance relationship findings are a striking reminder that mathematics governs
the universe. See e.g.
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