Iota Horologii


Iota Horologii, Latinized from ι Horologii, is a yellow-hued star approximately 56.5 light-years away in the Horologium constellation. The star is classified as a G0Vp yellow dwarf. It has a mass and radius larger than the Sun, and is about 50% more luminous.
In 1999, a planet of the star was discovered. Because the planet orbits in a near Earth orbit, Iota Horologii was ranked 69th in the list of candidates for NASA's planned Terrestrial Planet Finder mission. In 2000, a dust disc was announced around the star, but this was later determined to be an instrumental artifact.

Distance and visibility

Since Iota Horologii is in the minor constellation of Horologium and is quite dim in the sky, it has not been given a traditional name. It lies roughly between the stars Eta Horologii and R Horologii.
In its current position, Iota Horologii is closest to the star Chi Eridani, approximately 7 light-years away. The closest planetary systems to Iota Horologii are HD 10647, approximately 57 light-years away, and Epsilon Reticuli, approximately 59 light-years away. Other star systems close to Iota Horologii include Nu Phoenicis and Zeta Reticuli.

Properties

ic analysis indicates the star must have formed together with the stars of the Hyades cluster but must have slowly drifted away, being presently more than 130 light-years away from its original birthplace. The metallicity of the star matches the abundances found in the Hyades, indicating that the metals in the atmosphere were not acquired because it engulfed planetary material.
Measurements of magnetic activity with the 1.5 m telescope at Cerro Tololo Inter-American Observatory show that the star has a 1.6 year magnetic activity cycle which, as of 2010, is the shortest cycle measured so far for a solar like star. The sun by comparison has an 11-year magnetic activity cycle. There may be a second, longer cycle which modulates the 1.6 year cycle.

Planetary system

Iota Horologii b is believed to be Jupiter-sized. The planet's discovery was the result of a survey of forty stars that began in November 1992.
Stability analysis reveals that the orbits of Earth-sized planets located in the planet's trojan points would be stable for long periods of time.
Based on residuals in the radial velocity curve, a planet in an eccentric orbit with a period of approximately 600 days was proposed, but this was not confirmed and it seems likely that the effect was due to activity on Iota Horologii itself.