Iota Horologii
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Horologium |
| Right ascension | 02h 42m 33.47s[1] |
| Declination | -50° 48′ 01.1″[1] |
| Apparent magnitude (V) | +5.40 |
| Characteristics | |
| Spectral type | G0Vp |
| B−V color index | 0.57 |
| Variable type | none |
| Astrometry | |
| Radial velocity (Rv) | 15.5 km/s |
| Proper motion (μ) | RA: 332.82 ± 0.19[1] mas/yr Dec.: 218.74 ± 0.18[1] mas/yr |
| Parallax (π) | 58.25 ± 0.22[1] mas |
| Distance | 56.0 ± 0.2 ly (17.17 ± 0.06 pc) |
| Absolute magnitude (MV) | 4.27 |
| Details | |
| Mass | 1.25 ± 0.01[2] M☉ |
| Radius | 1.16 ± 0.04[3] R☉ |
| Luminosity | 1.64 ± 0.05[3] L☉ |
| Temperature | 6,080[3] K |
| Metallicity [Fe/H] | 0.14-0.19[2] dex |
| Rotation | 8.6 days |
| Age | 0.625[2] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Iota Horologii (ι Hor, ι Horologii) is a solar twin, yellow dwarf star approximately 56 light-years away[1] in the constellation of Horologium (the Pendulum Clock). The star is classified as a G0Vp[4] 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.[5]
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[edit] 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 (though it is not close to them in real space).
In its current position, Iota Horologii is closest to the star Chi Eridani (a yellow subgiant), approximately 7 light-years away. The closest planetary systems 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 systems close to Iota Horologii include Nu Phoenicis and Zeta Reticuli.[4]
[edit] Physical properties
Spectrographic 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.[2]
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 is the shortest cycle measured so far for a solar like star. The sun by comparison has a 11 year magnetic activity cycle.[6]
[edit] Planetary system
As of 1998, Iota Horologii is known to have a Jupiter-sized 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.[7]
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.[5]
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.[8]
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.[citation needed]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| b | ≥2.24 ± 0.13 MJ | 0.91 | 311.3 ± 1.3 | 0.22 ± 0.06 |
[edit] See also
[edit] References
- ^ a b c d e f van Leeuwen, F. (2007). "HIP 12653". Hipparcos, the New Reduction. http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=12620. Retrieved 2010-01-27.
- ^ a b c d Vauclair, S. et al (2008). "The exoplanet-host star iota Horologii: an evaporated member of the primordial Hyades cluster". Astronomy and Astrophysics 482 (2): L5–L8. arXiv:0803.2029v1. Bibcode 2008A&A...482L...5V. doi:10.1051/0004-6361:20079342. http://www.aanda.org/articles/aa/full/2008/17/aa9342-07/aa9342-07.html.
- ^ a b c Bruntt, H. et al. (July 2010), "Accurate fundamental parameters for 23 bright solar-type stars", Monthly Notices of the Royal Astronomical Society 405 (3): 1907-1923, Bibcode 2010MNRAS.405.1907B, doi:10.1111/j.1365-2966.2010.16575.x
- ^ a b "Iota Horologii". SolStation. http://www.solstation.com/stars2/iotahoro.htm. Retrieved 2008-05-28.
- ^ a b "Retracted in August 2001: ADONIS Discovers Dust Disk around a Star with a Planet". European Southern Observatory. 2000-10-13. http://www.eso.org/public/outreach/press-rel/pr-2000/phot-27-00.html. Retrieved 2011-12-21.
- ^ Metcalfe, T. S. et al (2010). "Discovery of a 1.6 Year Magnetic Activity Cycle in the Exoplanet Host Star ι Horologii". The Astrophysical Journal Letters 723 (2): L213–L217. arXiv:1009.5399. doi:10.1088/2041-8205/723/2/L213. http://iopscience.iop.org/2041-8205/723/2/L213/fulltext/.
- ^ Kürster, M. et al (2000). "An extrasolar giant planet in an Earth-like orbit. Precise radial velocities of the young star iota Horologii = HR 810". Astronomy and Astrophysics 353 (3): L33–L36. Bibcode 2000A&A...353L..33K. http://aa.springer.de/papers/0353003/2300l33/small.htm.
- ^ Schwarz, R. et al (2007). "Survey of the stability region of hypothetical habitable Trojan planets". Astronomy and Astrophysics 474 (3): 1023–1029. Bibcode 2007A&A...474.1023S. doi:10.1051/0004-6361:20077994. http://www.aanda.org/articles/aa/full/2007/42/aa7994-07/aa7994-07.html.
- ^ Naef, D. et al (2001). "The CORALIE survey for southern extrasolar planets V. 3 new extrasolar planets". Astronomy and Astrophysics 375 (1): 205–218. arXiv:astro-ph/0106255. Bibcode 2001A&A...375..205N. doi:10.1051/0004-6361:20010841. http://www.aanda.org/articles/aa/full/2001/31/aa10239/aa10239.html.
[edit] External links
- Emily Baldwin. "The Drifting Star". http://www.astronomynow.com/Thedriftingstar.html. Retrieved 2008-04-18.
- "Extrasolar Giant Planet in Earth-like Orbit". European Southern Observatory. http://www.eso.org/outreach/press-rel/pr-1999/pr-12-99.html. Retrieved 2008-06-12.
- "Iota Horologii". Extrasolar Visions. http://www.extrasolar.net/startour.asp?StarCatId=&StarId=20. Retrieved 2008-06-12.
- "Iota Horologii". SolStation. http://www.solstation.com/stars2/iotahoro.htm. Retrieved 2008-06-12.
- "Notes for star HR 810". The Extrasolar Planets Encyclopedia. http://exoplanet.eu/star.php?st=HR+810. Retrieved 2008-06-23.
Coordinates: 
02h 42m 31.65s, −50° 48′ 12.29″
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