Iota Horologii
Encyclopedia
Iota Horologii (ι Hor, ι Horologii) is a solar twin, yellow dwarf
star
approximately 56 light-year
s away in the constellation
of Horologium
(the Pendulum Clock
). The star is classified as a G0Vp yellow dwarf
(it has previously been classified as G3 and a subgiant [IV]). It has a mass and radius larger than the Sun
, and is about 50% more luminous.
As of 1998, a single extrasolar planet
is known orbiting Iota Horologii. 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.
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
(though it is not close to them in real space).
Spectrograph
ic analysis indicates the star must have formed together with the stars of the Hyades cluster (~625 million years ago) but must have slowly drifted away, being presently more than 130 light-years away from its original birthplace. This also means that the amount of metals present in the star is due to the original cloud from which it formed and not because it engulfed planetary material.
In its current position, Iota Horologii is closest to the star Chi Eridani (a yellow subgiant), approximately 7 light-years away. The closest planetary system
s to Iota Horologii are HD 10647
(a yellow dwarf
), approximately 9 light-years away, and Epsilon Reticuli
(an orange subgiant), approximately 16 light-years away. Other star system
s close to Iota Horologii include Nu Phoenicis
and Zeta Reticuli
.
. 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 However further analysis revealed the dust disc to be an instrumental artifact and the discovery claim was retracted.
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.
Yellow dwarf
A G-type main-sequence star , often called a yellow dwarf, is a main-sequence star of spectral type G and luminosity class V. Such a star has about 0.8 to 1.2 solar masses and surface temperature of between 5,300 and 6,000 K., Tables VII, VIII...
star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
approximately 56 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
of Horologium
Horologium
Horologium is a small and faint constellation in the southern sky . Its name is Latin for clock. It was created in the 18th century by Abbé Nicolas Louis de Lacaille, who originally named it Horologium Oscillitorium after the pendulum clock to honour its inventor, Christiaan Huygens...
(the Pendulum Clock
Pendulum clock
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is a resonant device; it swings back and forth in a precise time interval dependent on its length, and resists swinging at other rates...
). The star is classified as a G0Vp yellow dwarf
Yellow dwarf
A G-type main-sequence star , often called a yellow dwarf, is a main-sequence star of spectral type G and luminosity class V. Such a star has about 0.8 to 1.2 solar masses and surface temperature of between 5,300 and 6,000 K., Tables VII, VIII...
(it has previously been classified as G3 and a subgiant [IV]). It has a mass and radius larger than the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
, and is about 50% more luminous.
As of 1998, a single extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
is known orbiting Iota Horologii. Because the planet orbits in a near Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
orbit, Iota Horologii was ranked 69th in the list of candidates for NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's planned Terrestrial Planet Finder
Terrestrial Planet Finder
The Terrestrial Planet Finder was a proposed project by NASA to construct a system of telescopes for detecting extrasolar terrestrial planets. TPF was postponed several times and finally cancelled...
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 HorologiumHorologium
Horologium is a small and faint constellation in the southern sky . Its name is Latin for clock. It was created in the 18th century by Abbé Nicolas Louis de Lacaille, who originally named it Horologium Oscillitorium after the pendulum clock to honour its inventor, Christiaan Huygens...
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
R Horologii
R Horologii is a red giant star approximately 100 light-years away in the constellation Horologium. It is also a Mira variable with a period of 407.6 days, and has one of the largest magnitude ranges known .- External links :* *...
(though it is not close to them in real space).
Spectrograph
A spectrograph is an instrument that separates an incoming wave into a frequency spectrum. There are several kinds of machines referred to as spectrographs, depending on the precise nature of the waves...
ic analysis indicates the star must have formed together with the stars of the Hyades cluster (~625 million years ago) but must have slowly drifted away, being presently more than 130 light-years away from its original birthplace. This also means that the amount of metals present in the star is due to the original cloud from which it formed and not because it engulfed planetary material.
In its current position, Iota Horologii is closest to the star Chi Eridani (a yellow subgiant), approximately 7 light-years away. The closest planetary system
Planetary system
A planetary system consists of the various non-stellar objects orbiting a star such as planets, dwarf planets , asteroids, meteoroids, comets, and cosmic dust...
s to Iota Horologii are HD 10647
HD 10647
HD 10647, also known as q1 Eridani by the extended Bayer system, is a yellow-white dwarf star approximately 57 light-years away in the constellation of Eridanus . It is a relatively nearby 6th magnitude star. The star should be visible to the unaided eye under very dark skies, but with...
(a yellow dwarf
Yellow dwarf
A G-type main-sequence star , often called a yellow dwarf, is a main-sequence star of spectral type G and luminosity class V. Such a star has about 0.8 to 1.2 solar masses and surface temperature of between 5,300 and 6,000 K., Tables VII, VIII...
), approximately 9 light-years away, and Epsilon Reticuli
Epsilon Reticuli
Epsilon Reticuli is a binary system approximately 59 light-years away in the constellation of Reticulum. The primary star is an orange subgiant star, while the secondary star is a white dwarf star. The primary star should be easily visible without optical aid under dark skies in the southern...
(an orange subgiant), approximately 16 light-years away. Other star system
Star system
A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.-Binary star systems:A stellar...
s close to Iota Horologii include Nu Phoenicis
Nu Phoenicis
Nu Phoenicis is a main sequence dwarf star in the constellation Phoenix. It is similar to the Sun, although somewhat more massive and luminous...
and Zeta Reticuli
Zeta Reticuli
Zeta Reticuli is a binary star system located about away from Earth. It is located in the constellation Reticulum, and is visible to the unaided eye in very dark skies...
.
Planetary system
As of 1998, Iota Horologii is known to have a Jupiter-sized extrasolar planetExtrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
. The planet designated Iota Horologii b
Iota Horologii b
Iota Horologii b , often catalogued HR 810 b, is an extrasolar planet approximately 50 light-years away in the constellation of Horologium...
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
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
, similar to the Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...
in our solar system. However further analysis revealed the dust disc to be an instrumental artifact and the discovery claim was retracted.
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.
See also
- Iota Horologii in fiction
- Gliese 570Gliese 570Gliese 570, also known as 33 G. Librae, is a ternary star system approximately 19 light-years away. The primary star is an orange dwarf star . The other secondary stars are themselves a binary system, two red dwarfs that orbit one another. A brown dwarf has been confirmed to be orbiting in the...