New method of detecting exoplanet: observation of near-star discs

New method of detecting exoplanet: observation of near-star discs

A recent study has shown that using ALMA data on young stars' near-star discs, exoplanets can be detected.

The methods of transit and radial velocity are the most effective methods of determining exoplanet. The number of worlds discovered to date outside the solar system has exceeded 5,000. However, although this number is large, it is a small number compared to the zoo of such objects that are expected to be found in the universe. Various technologies and new search techniques are needed to expand the search and understanding of these bodies.

A recent study used information collected by the ALMA radio interferometer on near-stellar discs surrounding young stars to detect exoplanet, a method that may be a new technique for identifying these objects that can be observed at a critical stage in their formation.

Inside the near-star disks

In the early stages of its evolution, the star is surrounded by a disk of dust and gas. In this structure, thanks to the gravity of the star and the instability of the disc, the formation of planets begins.

The ALMA radio interferometer found several near-stellar discs around very young stars in Chile. The images show holes and stripes inside these structures, and their causes may be very different, such as the formation of an exoplanet or the influence of turbulence and gravity within the disk.

The ALMA resolution does not allow direct observation of the planet, but other features in the disc structure can be the key to discovery. A giant planet that is already in the early stages of accretion can gravitationally affect the dust and gas surrounding its orbit.

Gravity of an exoplanet

One example is Jupiter, who has a gravitational effect on small bodies in two different ways:

  • Kirkwood's slits characterize the distribution of asteroids in the main belt. These are the real failures in the number of asteroids in orbital resonations with Jupiter. Trojan asteroids, the accumulation of small bodies trapped in Jupiter's Lagrangian orbits, located 60 degrees before and after Jupiter, and their existence is due to the interaction between the gravity forces provided by Jupiter and the Sun on each other.

Massive exoplanet can have an equally significant impact on its environment. These interactions can be seen, for example, in a near-star disk.

LkCA 15

The research group that proposed this approach studied the star LkCA 15 and the structure of the gas and dust around it. The aim was to detect traces of gravitational interaction between a possible planet and its star.

Looking at the disk, the researchers discovered two very dull accumulations of dust. They perform the same orbit, divided by an angle of 120 degrees. Their characteristics suggest the placement of gas and dust at two points in Lagrangia, a young planet. The latter was to form very quickly, reaching the size of Neptune or Saturn in two million years, so it would seem that the gravitational interaction of a massive planet begins at the earliest stages of its formation.

The result shows that this technique can become an extremely important investigative tool, and astronomers will now look for other planets orbiting young stars using the same method to help supplement the universe with new worlds that are just waiting for their discovery.