Zeta Doradus, Latinized from ζ Doradus, is a young star system that lies approximately 38

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s away. The system consists of two widely separated stars, with the primary being bright enough to be observed with the naked eye but the secondary being much a much fainter star that requires telescopic equipment to be observed.

Components

Zeta Doradus A is a bright, high proper motion star with a spectral type of F7V, meaning that it is a

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

star that is hotter and brighter than the Sun. With an apparent magnitude of 4.82, it is approximately the eighth brightest star in the constellation of Dorado. Though it has been known that Zeta Doradus B is a nearby star since at least the Gliese Catalogue of Nearby Stars, the connection that it is a

common proper motion This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outsid ...

companion to Zeta Doradus A was only made much more recently thanks to Hipparcos satellite data. The two stars form a wide binary, with a physical separation between the components of about 0.018 parsecs (0.06 light-years) which is approximately 3700 AU. This is comparable to the 15000 AU separation between

Alpha Centauri Alpha Centauri ( Latinized from α Centauri and often abbreviated Alpha Cen or α Cen) is a triple star system in the constellation of Centaurus. It consists of 3 stars: Alpha Centauri A (officially Rigil Kentaurus), Alpha Centaur ...

AB and

Proxima Centauri Proxima Centauri is a small, low-mass star located away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest tarof Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest-kno ...

. Both components of the system show considerable activity: the log R'_HK of the stars are -4.373 and -4.575, respectively, whereas a star is "quiet" when it has a Log R'_HK of <-4.8. This indicates that the system is young; indeed, the estimated age for Zeta Doradus A is only 0.58 billion years, about an eighth of the solar age. It is not unusual for a young star to possess a debris disk; Zeta Doradus A is no exception, as it has been found to have an infra-red excess indicative of a disk of small bodies like comets re-emitting absorbed light at a redder wavelength. For Zeta Doradus A, the dust disk has a luminosity of 6.0 x 10⁻⁶ times the solar luminosity and a temperature of 91 ± 12 Kelvin, indicating that it lies at a separation of several AU.

Planet searches

Stars of early spectral type (>F8) are often ignored by radial velocity (RV)-based planet searches due to issues with precision: their high temperature decreases the depth of their spectral lines and they tend to be fast rotators, which broadens their spectral lines. Still, it is still sometimes possible to reach levels of precision capable of the detection of planets in AF-type stars, so Zeta Doradus A was included in a sample early-type stars observed with

HARPS The High Accuracy Radial Velocity Planet Searcher (HARPS) is a high-precision echelle planet-finding spectrograph installed in 2002 on the ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003. H ...

. The star was found to be RV-stable to 17 m/s with internal uncertainties of 3 m/s, which indicates that the star does not have any close-in high mass companions, but does not preclude the presence of sub-Jovian mass planets.

References

External links

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NStars: 0505-5728
{{DEFAULTSORT:Zeta Doradus F-type main-sequence stars Solar-type stars K-type main-sequence stars Binary stars Circumstellar disks Dorado Doradus, Zeta Durchmusterung objects 0189 033262 023693

1674 Events January–March * January 2 – The French West India Company is dissolved after less than 10 years. * January 7 – In the Chinese Empire, General Wu Sangui leads troops into the Giuzhou province, and soon takes cont ...