Astronomers have reported discovering what is considered a “miniaturized” solar system and another star system home to some of the youngest rocky planets discovered to date.
As revealed by the astronomers, the mass of seven exoplanets, located in two multiple planetary systems (K2-32 and K2-233), has been measured by an international team led by the Center for Astrobiology (CAB). The first of the systems, with four planets, is a reduced version of the Solar System, and the second hone out there is actually home to the two of the youngest rocky exoplanets known to date.
This latest discovery opens the door for the study of the early phases of rocky planets like Earth, something that will shed light on the evolution of our planet, and how life came into existence.
One of the great questions in astrobiology is the study of exoplanets, planets that orbit around stars other than the Sun. Currently, more than 4,000 exoplanets have been discovered (confirmed by NASA), and the list is an ever-growing one. Ther are 5,219 candidate exoplanets as of June 2, 2020.
Within this astrobiological context, it is of paramount importance to be able to obtain accurate information on the atmospheric properties of extrasolar planets. To study their atmospheres and understand their internal structure, one of the key pieces is to accurately measure the mass and size of planets.
With this in mind, experts developed the ESO-K2 collaboration in which a selection of planetary systems detected with the K2 mission has been studied, using the HARPS instrument at the La Silla Observatory (Chile).
In the context of this collaboration, a scientific team led by the CAB has managed to measure the masses, densities and orbital parameters of two multi-planetary systems: the K2-32 system, made up of four planets; and the K2-233 system, a young planetary system (less than 400 million years old) consisting of three planets.
The results have recently been published in the journal ‘Astronomy & Astrophysics’.
The results of the study show that the K2-32 planetary system is a compact and reduced version of the Solar System, with a rocky planet in the inner zone of the system (K2-32 e), followed by a gas giant of the mass of Neptune ( K2-32 b) and by two mini-Neptune-type planets in the outermost zone (K2-32 c and K2-32 d).
But they are all in an orbit twice as small as that of Mercury.
In this way, K2-32 is one of the few multi-planetary systems with four or more known planets where all the masses and radii of their planets are known.
The second planetary system studied by astronomers, K2-233, contains two Earth-sized, rocky inner planets (K2-233 b and K2-233 c) and a mini-Neptune-type outer planet (K2-233 d).
In the case of K2-233, astronomers measured for the first time the mass of two rocky planets in a young star, about 600 million years old, revealed Jorge Lillo Box, a postdoctoral researcher of the María de Maeztu program at the CAB and the study’s author.
They are the youngest rocky planets known to date, both with densities similar to Earth. This opens the door for the first time to the study of the earliest history of planets like Earth.
Furthermore, as revealed by astronomers, all these planets transit (eclipse their star), making them a reference for future observations with the James Webb Space Telescope to characterize their atmospheres, added David Barrado, CAB researcher and co-author of the study, who highlights in a statement that “there are very few planets whose ages are known in a sufficiently precise way and this fact is very important to confront the study data with theoretical models and to understand the context of the evolution of its properties.”