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Zeta Reticuli

Zeta1,2 Reticuli

Proper NameNone
Bayer DesignationZeta1,2 Centauri
Flamsteed NumberNone
HR (BSC)1006 (Zeta1), 1010 (Zeta2)
HD20766 (Zeta1), 20807 (Zeta2)
Right Ascension3h 17m 46s (Zeta1), 3h 18m 13s (Zeta2)
Declination-62° 34' 31" (Zeta1), -62° 30' 23" (Zeta2)
Distance39 light years
12 parsecs
MagnitudeApparent: +5.54 (Zeta1), +5.23 (Zeta2)
Absolute: +5.13 (Zeta1), +4.82 (Zeta2)
Spectral ClassG2.5VHdel1 yellow dwarf (Zeta1), G1V yellow dwarf (Zeta2)
Optimum VisibilityNovember / December (Usually visible from southern latitudes)
NotesThe Zeta Reticuli system is composed of a binary pair of stars, each of which is a yellow dwarf, somewhat Sun-like in nature, but rather smaller and less massive than the Sun. The stars of this system orbit one another at a distance of some 4,000 Astronomical Units, and the entire system lies a little less than forty light years from the Solar System.

A binary star in the skies of Earth's southern hemisphere. Lying roughly halfway between the Large Magellanic Cloud and the bright star Achernar in the sky, Zeta Reticuli falls within the boundaries of Reticulum, near its western border with Horologium. The stars that make up this binary pair are spaced widely apart, and easily resolved as a double star.

The stars of the Zeta Reticuli system are both of the G-type (yellow) classification, and each is closely similar to the Sun, which is also a G-type main sequence star (though both the yellow dwarfs of Zeta Reticuli are marginally smaller and less massive than the Sun). These stars orbit one another at a vast distance - estimated at a little under 4,000 AU, or about 5% of a light year - and take a period of at least 170,000 years to complete one of their mutual orbits.

Zeta1 Reticuli appears to the southwest (lower right in this image), while Zeta2 Reticuli is to the northeast (upper left). The two stars are extremely similar in type and in magnitude, but Zeta2 Reticuli is marginally the brighter of the pair. Imagery provided by Aladin sky atlas

Zeta2 (the northerly of the two components) is fractionally larger and more luminous than its companion, and evidence suggests that it has a disc of debris in orbit. This disc is somewhat comparable to the Solar System's Asteroid Belt, though it orbits farther from its parent star.

An analysis of the relative motion of the Zeta Reticuli system places it within a group of about ten related stars that are thought to share a common origin, but are now scattered throughout the sky. Within the same group of stars is Beta Hydri, another yellow star in the same general area of the southern sky. The entire group is more widespread than this might suggest, and its brightest member is Zeta Herculis (from which the entire Zeta Herculis Moving Group takes its name) which lies in the northern constellation of Hercules.


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