HD 219828 is a star with 1.18 times the mass of the Sun, and 1.61 times its radius. It is located 238.47 light years away from the solar system and is estimated to be 5.69 billion years old, as compared to the Sun which is roughly 4.6 billion years old.
HD 219828 is known to have 2 exoplanets in orbit around it.
HD 219828 b was discovered by the La Silla Observatory observatory, in 2007-05, using the radial velocity method. Its semi-major axis is 0.05 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of HD 219828 b is 20.988 times the mass of Earth. The radius of HD 219828 b is 4.850 that of Earth. At more than 10 Earth masses, HD 219828 b is an ice giant, a planet that is made up mostly of volatiles like water, amonia and methane, and enveloped by a dense hydrogen and helium atmosphere, much like Uranus and Neptune in our solar system.
HD 219828 c was discovered by the Multiple Facilities observatory, in 2016-07, using the radial velocity method. Its semi-major axis is 5.79 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of HD 219828 c is 4642.800 times the mass of Earth. The radius of HD 219828 c is 12.300 that of Earth. At more than 50 Earth masses, HD 219828 c is a gas giant, a planet whose mass is mostly made up of hydrogen and helium, like Jupiter and Saturn in our solar system.