English: Ever wondered how planetary systems like our own Solar System form? Thanks to the European Space Agency’s Gaia space telescope, we're getting a unique peek behind the cosmic curtain into these dusty environments.
In this collage, we see the images of 31 baby star systems. Click on the white dots next to each system to find out more about them. The bar on the top right shows the scale of the image in Astronomical Units (AU).
The collage also shows our own Solar System for reference on the bottom right, as it is predicted to have looked at an age of 1 million years, with the Sun at its centre (not visible).
All of the systems are centred around very young stars that have recently collapsed from vast clouds of gas and dust.
After the clouds collapsed under their own gravity, they spun faster and flattened into discs with hot, dense centres. These centres became the stars, sometimes multiple stars were formed. The discs around them are called protoplanetary discs.
The 31 baby systems are shown here in orange-purple, as seen by the Atacama Large Millimeter Array (ALMA) ground-based telescope.
Astronomers expect the remaining material in protoplanetary discs to clump together to form planets, but until now it’s been very difficult to spot them because of all the dust and gas present in discs. To date, very few planets have been detected around forming stars.
Enter Gaia.
In 31 out of 98 young star systems, Gaia has detected subtle motions that suggest the presence of unseen companions. For seven of these systems, the observed motions are consistent with objects of planetary mass. In eight systems, the data best match the presence of brown dwarfs – objects larger than planets but smaller than stars. The remaining sixteen systems likely have additional stars around.
Gaia’s predicted locations of these companions in the systems are shown in cyan. In the reference image of our baby Solar System, Jupiter’s orbit is also shown in cyan.
Gaia discovered the companions in the baby star systems thanks to its unique ability to sense the gravitational tug or ‘wobble’ a planet or companion induces on a star. This technique had already been used to find companions around older stars. But now, for the first time, a team of astronomers led by Miguel Vioque of the European Southern Observatory, Germany, has used this Gaia technique to find planets and companions around stars that are still forming.
The all-sky, large-scale nature of the Gaia survey enabled the team to study hundreds of forming stars and identify companions across large samples for the first time. This in contrast to costly ground-based searches that can only target a few stars at a time.
This ability of Gaia is revolutionising the field of star and planet formation. The companions that the telescope has already found, can now be followed up by telescopes like the NASA/ESA/CSA James Webb Space telescope that can study the inner discs of the baby systems in more detail.
With Gaia’s upcoming fourth data release, many more hidden planets are expected to be uncovered.
This new finding has been described in ‘Astrometric view of companions in the inner dust cavities of protoplanetary disks’ by M. Vioque et al., accepted for publication in Astronomy & Astrophysics.
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[Image description: A collage of 32 glowing discs on a black background. Each disc shows concentric rings in vivid colours: purple, orange, and yellow, with bright cyan centres. The discs vary in size and orientation, creating a striking pattern of circular and elliptical shapes.]