HD 181433

HD 181433 is a star with a system of orbiting exoplanets located in the southern constellation of Pavo (the Peacock). With an apparent visual magnitude of 8.40, it is too faint to be visible to the naked eye. It lies at a distance of 88 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +40 km/s. The system shows a high proper motion, traversing the celestial sphere at an angular rate of $$.

This K-type star has a stellar classification of K3III-IV, which presents it as an evolved star with mixed traits of a red giant and a subgiant. G. Campanella and associates list a class of K3IV. These are inconsistent with the fact that its luminosity is only 0.34 times that of the Sun. Its entry in the Hipparcos catalogue lists a spectral type of K5V, classifying it as an ordinary K-type main-sequence star, an orange dwarf.

HD 181433 is an older star with age estimates of around 7 billion years. It is smaller than the Sun, with 84% of the Sun's mass and 80% of the radius. This star is spinning with a projected rotational velocity of 1.6 km/s. The effective temperature of the stellar atmosphere is 4,909 K.

Planetary system
Orbiting the star are three planets, whose discovery was announced in 2008; the discovery paper was published in 2009. The inner planet has a mass at least 7.5 times that of Earth, and is termed a super-Earth (this classification is based solely on the mass of the planet and should not be taken to imply that the planet could support Earthlike conditions). The middle planet and the outer planet are gas giants. The orbital periods for three planets are 9.3743 days for a 7.56 ME planet, 962 days for a 0.64 MJ planet, and 2172 days for a 0.54 MJ planet. This solution is unstable, more data are required to constrain the orbital position of planet d.