First ever image of a multi-planet system around a Sun-like star

Astronomers have captured the first ever image of a multi-planet system around a star similar to our Sun. The star, named TYC 8998-760-1, is located about 300 light-years away from Earth and is only 17 million years old. The image, taken by the SPHERE instrument on ESO's Very Large Telescope, shows two giant exoplanets orbiting the star at distances of 160 and 320 astronomical units (au), respectively. For comparison, Neptune orbits the Sun at about 30 au.

Image credit : eso

The discovery, published in The Astrophysical Journal Letters, is a milestone for direct imaging of exoplanets, which are planets outside our Solar System. Direct imaging is a challenging technique that requires blocking the bright light of the host star to reveal the fainter planets around it. Most of the exoplanets that have been directly imaged so far are either very young or very massive, and orbit very far from their stars. This makes them easier to detect, but also less representative of the majority of exoplanets in our galaxy.

The two planets around TYC 8998-760-1 are both gas giants, with masses of 14 and 6 times that of Jupiter. They are also very cold, with temperatures of about -160°C and -250°C, respectively. Their orbits are very wide, comparable to those of dwarf planets in the outer Solar System. Such wide orbits are rare among the known exoplanets and pose a challenge for planet formation theories. How did these planets form so far from their star? Did they migrate from closer in, or did they form in situ from a massive disk of gas and dust?

The researchers who made the discovery used several observations with SPHERE and NACO, two instruments that can perform high-contrast imaging at different wavelengths. They combined different techniques to reduce the noise and enhance the signal of the planets. They also confirmed that the planets are gravitationally bound to the star by measuring their relative motion over several months.

The team plans to follow up this system with more observations in the future, using both ground-based and space-based telescopes. They hope to learn more about the properties and atmospheres of these planets, as well as their formation history. They also hope to find more examples of multi-planet systems around Sun-like stars, which could shed light on the diversity and evolution of planetary systems in our galaxy.

TYC 8998-760-1 is an ideal system for spectroscopic and photometric studies with upcoming facilities such as the James Webb Space Telescope (JWST). Due to the wide separations of the planets, they will not be affected by the glare of the star and will be easier to characterize. The system also offers a unique opportunity to study how planets interact with each other and with their star over long timescales.

This image is one of the most stunning examples of what SPHERE can do. SPHERE is an instrument that was designed to image exoplanets and disks around nearby stars. It is one of the flagship projects of ESO, the European Southern Observatory, which operates some of the most advanced telescopes in the world. ESO is an intergovernmental organization that supports cutting-edge research in astronomy and astrophysics.