A team of international astronomers have discovered four new giant exoplanets with very short orbital periods. The four planets, which have been named HATS-74Ab, HATS-75b, HATS-76b, and HATS-77b, are all about the same size as Jupiter.
The discoveries were made during the HATSouth photometric survey. HATSouth includes six astrograph telescope systems that are in South America, Africa, and Australia. Launched in 2009, the telescopes are trained to discover exoplanets that are orbiting bright stars that can be seen from the Southern Hemisphere and they have already found dozens of transiting exoplanets.
The four new giant planets were revealed with the HATSouth telescopes and were later confirmed by additional observations conducted by NASA's Transiting Exoplanet Survey Satellite (TESS) as well as several other facilities. The planets were found by transiting signals coming from four stars -- HATS-74A, HATS-75, HATS-76, and HATS-77.
As for the newly discovered planets, HATS-74Ab is located about 934 light-years away from us and is approximately the same size as Jupiter but with 46% more of its mass. It is situated 0.024 Astronomical Units (AU) away from its host star (one AU is the distance that Earth is to our sun) with an orbital period of just 1.73 days. Its equilibrium temperature is 895 Kelvin (1,151 degrees Fahrenheit or 622 degrees Celsius). The 11-billion-year-old parent star has a radius around 0.57 of our sun and about 0.6 solar masses with a temperature of 3,777 Kelvin (6,339 degrees Fahrenheit or 3,504 degrees Celsius). Interestingly, it has a companion star that is approximately 80% less massive than our sun.
Located about 637 light-years away, HATS-75b is the smallest of the four exoplanets with a radius of about 0.88 of Jupiter and 0.49 of its mass. It is about 0.032 AU from its star and takes 2.79 days to complete a full orbit around it. It has an equilibrium temperature of 772.3 Kelvin (930 degrees Fahrenheit or 499 degrees Celsius). The 15-billion-year-old parent star has a radius of 0.58 of our sun and 0.6 of its mass with a temperature of 3,790 Kelvin (6,362 degrees Fahrenheit or 3,517 degrees Celsius).
The third planet is called HATS-76b and is located about 1,271 light-years away. It is approximately 2.63 times more massive than Jupiter and 1.08 of its radius. It is found 0.026 AU from its star with an orbital period of 1.94 days. It is the hottest planet of the four with an equilibrium temperature of 939.8 Kelvin (1,232 degrees Fahrenheit or 667 degrees Celsius). The 4.6-billion-year-old host star has 0.66 solar masses with 0.62 of its radius and a temperature of 4,016 Kelvin (6,769 degrees Fahrenheit or 3,743 degrees Celsius).
The fourth star named HATS-77b is located about 1,349 light-years away. It is around 16% bigger than Jupiter with a 37% greater mass. It travels around its host star at a distance of 0.036 AU and takes 3.09 days to complete a full orbit. Its temperature is 828.3 Kelvin (1,031 degrees Fahrenheit or 555 degrees Celsius). The 12.1-billion-year-old star is about 35% smaller and less massive than our sun with a temperature of 4,071 Kelvin (6,868 degrees Fahrenheit or 3,798 degrees Celsius).
The study on these four new planets can be read here.