Iota Horologii

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**Iota Horologii**
Observation data Epoch J2000.0
Constellation	Horologium
Right ascension	02^h 42^m 31^s 39^j
Declination	-50° 48' 12" 17.5’’’
Apparent magnitude (V)	+5.40
Spectral Characteristics
Spectral type	G0Vp
U-B color index	?
B-V color index	0.57
Variable type	none
Astrometry
Radial velocity (R_v)	15.5 km/s
Proper motion (μ)	RA: 333.73 mas/yr Dec.: 219.21 mas/yr
Parallax (π)	58.00 ± 0.55 mas
Distance	50.6 ly (16.8 pc)
Absolute magnitude (M_V)	?
Physical Characteristics
Mass	1.03 ± 0.02 M_☉
Radius	1.097 ± 0.019 R_☉
Luminosity	1.52 ± 0.05 L_☉
Temperature	6125 ± 30 K
Metallicity	[Fe/H] = +0.11 ± 0.04
Rotation	8.6 days
Age	30 – 2000 million years
Other designations
HR 810, HD 17051, GJ 108

Iota Horologii (ι Hor / ι Horologii) is a yellow dwarf star about 50 light-years away in the constellation Horologium (southwest of R Horologii). The star has been previously classified as G3 and a subgiant (IV). It has a similar mass and radius as our Sun, and is about 50% more luminous.

Since it is in the minor constellation of Horologium in the southern sky, it has no traditional name. The star exhibits higher chromospheric activity than the Sun and so is probably younger than Sol's 4.6 billion years. The closest known star to Iota Horologii is Chi Eridani which is a subgiant or giant star about 7.3 light-years away from Iota Horologii. The closest star to Iota Horologii known to have extrasolar planet is q1 Eridani, about 9.5 light-years away from Iota Horologii.

As of 1998, an extrasolar planet is known orbiting Iota Horologii. Iota Horologii is ranked 69th in the list of candidates for NASA's planned Terrestrial Planet Finder mission.

In 2000, a dust disc was announced around Iota Horologii, however this was later determined to be an instrumental artifact.

1 Planetary system
2 Works in Fiction
3 See also
4 References
5 External links

[edit] Planetary system

As of 1998, Iota Horologii is known to have an extrasolar planet. The planet designated Iota Horologii b was the result of a long-term survey of forty solar-type stars that was begun in November 1992.

Observations of Iota Horologii in October 2000 appeared to show a dust disc around the star at a distance of 65 AU, similar to the Kuiper belt in our solar system. However further analysis revealed the dust disc to be an instrumental artifact and the discovery claim was retracted.

Based on residuals in the radial velocity curve, a planet in an eccentric orbit with a period of approximately 600 days was proposed, however this was not confirmed and it seems likely that the effect was due to activity on Iota Horologii itself.

Companion (In order from star)	Mass (M_J)	Orbital period (days)	Semimajor axis (AU)	Eccentricity
b	>2.24 ± 0.13	311.3 ± 1.3	0.91	0.22 ± 0.06

[edit] Works in Fiction

In the science fiction novel Iota Cycle by Russell Lutz, Iota Horologii serves as a setting for colonization and terraforming. In the novel, Iota Horologii has six planets (Iota Horologii b being the second planet). The planets are referred to by a nickname after a continent. In order from closest to the star: Australia, Asia, Europe, Africa, America, and Antarctica (Asia being Iota Horologii b).

In the science fiction novel Outre Mer by [1] Michael Puttré, Iota Horologii is featured as the star system of the title world, which is an earthlike moon in orbit around the gas giant Adonis (Iota Horologii b). In the novel, Outre Mer is populated by human refugees, decendents of adbuctees taken by the Greys, inhabitants of the systems of Zeta Reticuli. The world is also the home of the duranni, an intelligent aboriginal species, and human-duranni interaction and conflict is one of the drivers of the novel's plot.