Kappa1 Ceti
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 03h 19m 21.7s |
| Declination | +03° 22′ 13″ |
| Apparent magnitude (V) | 4.84 |
| Characteristics | |
| Spectral type | G5V |
| U−B color index | 0.19 |
| B−V color index | 0.67 |
| Variable type | Suspected |
| Astrometry | |
| Radial velocity (Rv) | +19.9 km/s |
| Proper motion (μ) | RA: 268.87 mas/yr Dec.: 93.53 mas/yr |
| Parallax (π) | 109.18 ± 0.78 mas |
| Distance | 29.9±0.2 ly (9.16±0.07 pc) |
| Absolute magnitude (MV) | 5.03 |
| Details | |
| Mass | 0.9 M☉ |
| Radius | 0.96 R☉ |
| Luminosity | 0.85 L☉ |
| Temperature | 5,690 K |
| Metallicity | 110% Sun |
| Rotation | 8.9-10.5 days (4.64 km/s) |
| Age | 6.5-7.5×108 years |
| Other designations | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
Kappa1 Ceti (κ1 Cet / κ1 Ceti) is a yellow dwarf star approximately 30 light-years away in the constellation of Cetus. The star was discovered to have a rapid rotation that takes roughly once every nine days. Though there are no extrasolar planets confirmed to be orbiting the star, Kappa1 Ceti is considered a good candidate to contain terrestrial planets (like the Earth). The system is though to be a binary star, but has not been confirmed. The star should not be confused with the star Kappa2 Ceti (which is ten times as distant).
Stellar components
Kappa1 Ceti is a yellow dwarf star of the spectral type "G5Ve". The star is thought to have roughly the same mass as the Sun, along with a similar radius, but only 85 percent of the luminosity. It is unclear whether the star is equal or is more enriched in elements heavier than hydrogen, but it is determined that the star has between 98 and 240 percent of the Sun's abundance of iron. Kappa1 Ceti is much younger than the Sun, which may only be around 800 million year old.
The rapid rotation rate of this star, roughly once every nine days, is indicative of a relatively youthful body several hundred million years in age. Due to starspots, the star varies slightly over the approximately the same period. The variations in period are thought to be caused by differential rotation at various latitudes, similar to what happens on the surface of our Sun.[1] According to recent hypotheses, unusually intense stellar flares from a Solar twin star could be caused by the interaction of the magnetic field of a giant planet in tight orbit with that star's own magnetic field. Some Sol-type stars of spectral class "F8" to "G8" have been found have been observed to undergo enormous magnetic outbursts to produce "superflares" (coronal mass ejections) that release between 100 and 10 million times more energy than the largest flares ever observed on the sun, making them brighten briefly by up to 20 times.[2] These superflares last from one hour to one week and increase the normal luminosity of a star as much as one thousand times. If our sun were to produce a large superflare, Earth's ozone layer would be destroyed, and ice on the daylight side of moons as far out as those of Jupiter or even Saturn would be melted, producing vast floodplains that refreeze after the flare subsides. In 1998, nine Solar twin stars (including Kappa1 Ceti) were observed to have produced superflares, on average, about once per century. None of these stars rotate particularly fast, have close binary companions, or are very young. Previously, such large flares had not been observed in Sol-type main sequence stars, although they are common in a group of dim main-sequence, reddish "M" dwarfs known as flare stars.
Possible planetary system
Using the radial velocity technique, the search for substellar companions has thus far failed to find a brown dwarf or extrasolar planet in the "hot zone" orbit around Kappa1 Ceti. Given the regular eruption of superflares, however, it is unlikely that Earth-type life could survive for long on any inner terrestrial planet. The distance from the star where an Earth-type planet (with liquid water) would be stable is centered around 0.92 astronomical units from the star (between the orbital distances of Earth and Venus in the Solar system). At this distance, such a planet would have an orbital period of almost 324 days. Astronomers are hoping to use NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin Mission to search for a terrestrial planet in the habitable zone around Kappa1 Ceti.
See also
References
- ^ E. J. Gaidos, G.W. Henry, S.M.Henry, 2000, "Spectroscopy and Photometry of Nearby Young Solar Analogs", The Astronomical Journal, 120:1006-1013.
- ^ B. E. Schaefer, J.R. King, C.P. Deliyannis, 2000, "Superflares on Ordinary Solar-Type Stars", The Astrophysical Journal, Vol. 529, Issue 2, pp. 1026-1030.
External links
- Kaler, Jim. "KAPPA-1 CET". STARS. University of Illinois. Retrieved 2008-07-09.
- "Kappa Ceti". SolStation. Retrieved 2008-07-09.