Great advance in astronomy: here are the first images of the birth of a planet

Man does not stop trying to unravel the mysteries of the Universe and yet astronomy remains a domain with few certainties. Like humans, planets are born but so far scientists have not observed this phenomenon. It's official recently: a great telescope has made it possible to obtain snapshots of a "baby planet".

The first shots of the birth of a planet

The birth of planets is a mystery that astronomers are beginning to understand better. Last discovery, and not least: snapshots taken by a telescope of a "baby planet" in full growth. This is the first time that scientists can put images on the theory. The young planet in question creates a place within the disk of dust that surrounds its star, an orange dwarf located about 370 light years from the Earth . The star called PDS 70 has been known to astronomers for some time and they suspected the existence of a planet orbiting around it. The images confirm this theory: the young planet has been named PDS 70b. If we have a pretty solid idea about the formation of the planets, having confirmation of it has been more complicated.

So far, astronomers know that when the stars are formed, they are put into orbit by a swirling disc made of dust, stones and gas around the equator. The accumulation of materials forming the planets occur when these particles collide within the orbit. From this collision can thus be born a planet. Astronomers have already detected several protoplanetary disks of this type containing holes and even spectral data indicating the presence of planet. But to photograph the birth of a planet is not so simple

Researchers determined to discover this "baby planet"

This difficulty lies in several reasons. First, exoplanets are generally too far apart. On the other hand, their luminosity is too low to be spotted by telescopes, especially when the reflected light is hidden by the brightness of the star next to it (the same reason why you can not see the stars during the day). Despite these difficulties, the team of astronomers managed to do it. As early as 2012, a significant hole was discovered in the protoplanetary disc of PDS 70. This is where the research began at Max Planck Institute of Astronomy and at Observatory d Southern Europe . The researchers decided to move towards the discovery of a baby planet.

The astronomer Miriam Keppler of the Max Planck Institute of Astronomy evokes the difficulty of this research: "These discs around young stars are the birthplace of planets but so far only a handful of observations have detected traces of baby planets". She adds that "most of these candidates could very well be elements of the disc". Nevertheless, PDS 70 has several elements that make it a good candidate for this type of research. Its protoplanetary disk is large, covering a radius of about 130 AU (astronomical unit) knowing that the Kuiper belt measures only 50 AU. As an orange dwarf (with a mbad a little below that of Sun ), PDS 70 is not very bright, which is perfect for an observation with a coronograph. It is represented by the black circle in the center of the image, which blocks the bright light of the star and because of this, the other objects become visible.

Extensive research to learn more

Despite this, special filters had to be used to block particular wavelengths of light so that the other elements were visible. It was then that the "planet hunter" named SPHERE, installed on the very large ESO telescope, came into play. Using the coronograph and the polarization filters, the team discovered a very large planet in orbits in the hole of the PDS 70 disk. It would seem, moreover, that the process of accumulation of materials is still in progress. Further badyzes have been made, based on this spectrum.

PDS 70b has a mbad much higher than that of Jupiter and its orbit is about 22 AU (a little further than the orbit of Uranus around Sun ). It would take about 120 Earth years to make a complete turn around its star and the temperature of its surface is about 1200 Kelvin (about 927 ° C), which is huge. It is hotter than any planet in our solar system ( Venus is the hottest and its average temperature is 737 Kelvin). On the other hand, it seems that PDS 70b is surrounded by clouds, altering the radiation coming from its nucleus and the atmosphere. Even though this planet is not potentially habitable (the primary criterion for exoplanet research), this planet in formation is the first discovery of its kind, making it a major find for planetary science.

According to the astronomer André Müller of the Max Planck Institute "the results of Keppler open a new window on complex research about the evolution of planets ". The latter adds that "we needed to observe a planet in a record of a young star to really understand the processes hiding behind the formation of the planets."