The search for exoplanets has become a priority for the scientific community and the detection of some form of life, or of a planet that can host it, has been approached as the great challenge of the 21st century.
In this search, humanity has witnessed, for the first time in its history, an astonishing astronomical phenomenon: the birth of a planet. It is the first image obtained of a newborn planet around its star; and has been captured by the Max Planck Institute for Astronomy, in Heidelberg, Germany.
But, to the lullaby of its little star PDS 70, this planet, still in formation, looks nothing like Earth: it is several times larger than the most massive planet in the Solar System, Jupiter ; and it is also a gaseous planet. Of course, its surface is much warmer than that of any of our neighboring planets: between 1,300 and 1,900 degrees Celsius.
On the other hand, for its high temperature, the distance from its star is considerable: three billion kilometers, the equivalent of the distance between Uranus and the Sun.
And what about its star, PDS 70? It is an orange dwarf 370 light years distant from Earth.
The planet stands out very clearly in the observations, and is visible as a bright spot to the right of the blackened center of the image. This newborn has sculpted what is called a transitional disk, a ring of protoplanetary dust with a giant “hole” in the center. These internal lagoons have been known for decades and it has been speculated that they are produced by the disk-planet interaction. Indeed, it was so: now we can observe the new planet.
An impressive snapshot, captured by the SPHERE instrument on ESO’s Very Large Telescope (VLT) , one of the most powerful in terms of planet hunting.
Planet detection instruments are able to make these captures thanks to what is called a coronagraph, a mask that blocks the star’s light and allows astronomers to detect its passage. Otherwise, the light of the newborn planet would be dwarfed by that of its star.
The young gaseous planet has formed around its star in the traditional way that gaseous planets form: from the collapse of a gaseous disk.
“These disks around young stars are the birthplace of planets, but so far there have been very few observations of evidence of baby planets in them,” explains Miriam Keppler, who leads the team behind the discovery.
“The Keppler results give us a new window into the complex and poorly understood early stages of planetary evolution ,” says André Müller, leader of the second team to investigate the young planet. “We needed to observe a planet in the disk of a young star to really understand the processes behind the planet’s formation.”
Why is this detection useful?
In addition to the thrill of the event itself, by determining the atmospheric and physical properties of the planet, astronomers can test theoretical models of planet formation, and understand how the gaseous planets in our Solar System formed, as well as intuit how the planet is formed. rest.
The details of the detection have been published in two scientific articles in the prestigious journal Astronomy & Astrophysics.
References: M. Keppler, M. Benisty. ‘Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70’. (2018), Astronomy & Astrophysics.
M. Keppler, M. Benisty. ‘Orbital and atmospheric characterization of the planet within the gap of the PDS 70 transition disk’. (2018), Astronomy & Astrophysics.
