A team of astronomers discovered four new exoplanets. These extraterrestrial worlds – hot Jupiters – are similar in size but vary widely in mass. The results of this study are available on the arXiv Preprint server.
HATSouth is a network of six telescopes located in South America, Africa and Australia. These are designed to detect extrasolar planets transiting into orbit around relatively bright stars, visible from the southern hemisphere. Since its launch in 2009, the network has already detected dozens of new worlds in transit. This week, a team of astronomers led by Joao Bento, of the Australian National University (ANU), reports the discovery of four other planets orbiting four stars, subsequently confirmed by photometric and spectroscopic monitoring observations.
The new planets are called HATS-39b, HATS-40b, HATS-41b and HATS-42b. They have similar characteristics to the largest planet in the solar system, Jupiter, but with orbital periods of less than 10 days. These planets thus have very high surface temperatures because they orbit so close to their parent star.
With a mass of 0.63 mass of Jupiter, HATS-39b is the least massive exoplanet of the quartet. However, its radius – about 1.57 Jupiter’s radius – is larger than it should be. Thus, researchers describe HATS-39b as an “inflated planet”. The exoplanet revolves around its host every 4.58 days at a distance of 0.06 AU (one AU equals the Earth-Sun distance of about 150 million km). Its equilibrium temperature is 1370 degrees Celsius.
HATS-40b is about 58.5% larger and more massive than Jupiter. It takes the planet about 3.26 days to fully orbit its parent star, separated by about 0.05 AU. Its equilibrium temperature is estimated at about 1,825 degrees Celsius.
HATS-41b, it is about 33% larger than Jupiter, but nearly 10 times more massive than the largest planet in our solar system. According to the researchers, this is one of the most massive “hot Jupiters” found to date. The planet orbits around its star every 4.19 days, at about 0.06 AU. Its equilibrium temperature is about 1430 degrees Celsius.
HATS-42b, the last one, has a radius of 1.4 Jupiter rays and a mass of 1.88 mass of Jupiter. It orbits around itsstar every 2.29 days at about 0.037 AU distance. Its equilibrium temperature is 1,580 degrees Celsius.