HD 5608

HD 5608 is an orange-hued star in the northern constellation of Andromeda with one known planet, HD 5608 b. It is a dim star near the lower limit of visibility to the naked eye, having an apparent visual magnitude of +5.98. The distance to HD 5608, as estimated from an annual parallax shift of $−23.13$, is 191 ly. It is moving closer to the Earth with a heliocentric radial velocity of −23 km/s, and is expected to make its closest approach in 1.285 million years when it comes to within 38.03 pc.

This is a K-type subgiant star on the red giant branch track with a stellar classification of K0 IV. It has 1.5 times the mass of the Sun and, at the age of three billion years, has expanded to five times the Sun's radius. It is radiating 13 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,897 K. It has a higher than solar metallicity – a term astronomers use to describe the abundance of elements other than hydrogen and helium.

HD 5608 has a co-moving companion, HD 5608 B, at an angular separation of $146$, which has been directly imaged. The physical separation of the pair is calculated as $0.524$ or $30.7 AU$, depending on the assumptions. It has an H band magnitude difference of 9.40 with the primary and an estimated mass of. A second companion at a separation of $0.53$ is a background star. This companion star has since been characterized by radial velocity and astrometry in addition to imaging.

Planetary companion
In 2012, the Okayama Planet Search Program reported the detection of a substellar companion in orbit around HD 5608, based upon Doppler measurements between 2003 and 2011 from the Okayama observatory in Kurashiki. These showed a linear trend indicating the existence of a distant companion. The data showed an additional periodicity of around 766 days. This object shows a minimum mass of, a semimajor axis of $147.5$, and an eccentricity of 0.19. The high eccentricity of this planet could have been induced by the low mass companion star HD 5608 B via the Kozai mechanism.