New Delhi: Researchers have directly imaged an exoplanet designated as WISPIT 2b, a gas giant containing about five times the mass of Jupiter in orbit around the host star about 437 lightyears from the Earth. Astronomers have discovered over 6,000 exoplanets, with the detection methods favouring the discovery of large worlds in tight orbits around small stars. WISPIT 2b is between 56 and 58 Astronomical Units or AU from the host star, with a single AU being the distance between the Sun and the Earth which made the direct imaging easier. Despite the immense mass, the planet is still accreting mass from the environment, and is a protoplanet.
Illustration of WISPIT 2b. (Image Credit: NASA/JPL-Caltech/R. Hurt (IPAC)).
The object is of scientific interest as a giant planet in the process of being assembled, but its location in a gap in the protoplanetary disk surrounding the host star makes it even more fascinating. Stars are formed from dense knots in clouds of gas and dust that collapse under the influence of gravity, drawing in more of the surrounding material. Slight initial movement cause the infalling material to flatten into a swirling disk, falling inwards into the embryonic star. The planets are assembled in the material leftover from the birth of the star, which is why they are mostly all aligned in roughly the same plane around the host star.
A window to the past
About 4.6 billion years ago, such a protoplanetary disk surrounded a newborn Sun. It is possible that Jupiter and Saturn in our own Solar System may have cleared gaps in the circumstellar disk, just like WISPIT 2b is doing right now. Overall, yellow dwarf stars hosting gas giant planets are rare, and the Solar System is unusual for containing not one, but two gas giants. While scientists had worked out that giant planets would clear gaps in circumstellar disks in theory, WISPIT 2b is the first direct observational evidence in support of contemporary planet formation models. A paper describing the discovery has been published in the Astrophysical Journal Letters.