A team of European astronomers claims to have discovered eight new exoplanets – hot Jupiters – as part of the WASP project. The newly discovered gas giants have short orbital periods and masses ranging from 0.42 to 5.2 masses of Jupiter.
The cosmic address book fills up once again. The discovery was made as part of the SuperWasp project, which relies on two instruments installed on the sites of two observatories: the Roque de los Muchachos Observatory in the Canary Islands and the South African Astronomical Observatory. It is a team of researchers led by Coel Hellier from Keele University in the UK, who identified transit signals in the light curves of eight extrasolar worlds. The global nature of these signals was then confirmed by follow-up observations made in Chile.
All these new extraterrestrial worlds have been classified as “hot Jupiter”, similar in composition to the largest planet in our solar system – Jupiter – but with orbital periods of less than 10 days. Such exoplanets have high surface temperatures because they orbit very close to their parental stars. WASP-162b is the most massive planet among the eight with a mass of about 5.2 masses of Jupiter. It orbits around its parent star every 9.62 days at a distance of about 0.09 AU (astronomical unit) from the host. Recall that an AU equals the Earth-Sun distance of about 150 million km. Its surface temperature is 910 K (Kelvin). About one billion years old, its star is similar in size and mass to our Sun.
For its part, WASP-168b is the least massive planet listed in the document. However, although it has a mass of about 0.42 mass of Jupiter, its radius is 50% larger than that of Jupiter. Since this exoplanet proved to be larger than it should be, the researchers describe it as a swollen “hot Jupiter”. WASP-168b circles a star – about 10% larger and more massive than the Sun – every 4.15 days at a distance of 0.05 AU. The planet has a temperature of 1340 K.
The authors of the paper also point out that with respect to atmospheric characterization, the most promising of the new planets is WASP-172b. A low mass “Jupiter” (0.47 Jupiter mass, for 1.57 Jupiter radius) orbiting a relatively bright star every 5.47 days, and located at about 0.07 AU from its host. The remaining five exoplanets, designated WASP-144b, WASP-145Ab, WASP-158b, WASP-159b and WASP-173Ab have masses ranging from 0.44 to 3.7 Jupiter and radii between 0.85 and 1.4 Jupiter.