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Tureis, Turais, Scutulum, Iota Carinae

Proper NamesAspidiske, Tureis, Turais, Scutulum
Bayer DesignationIota Carinae
Flamsteed NumberNone
HR (BSC)3699
Right Ascension9h 17m 5s
Declination-59° 16' 31"
Distance766 light years
235 parsecs
MagnitudeApparent: +2.3
Absolute: -4.6
Spectral ClassA8Ib white supergiant
Optimum VisibilityFebruary / March (Usually visible from southern latitudes)

A relatively bright star on the Milky Way in the central regions of Carina, the Keel of the ship Argo. Aspidiske lies to the south of Vela, the ship's Sail, and is one of the four stars (with others from both Carina and Vela) that make up the asterism of the False Cross, an asterism similar in size and arrangement to Crux, the true Southern Cross.

Aspidiske has the alternative traditional name of Tureis (sometimes spelt Turais) making it one of two stars in the sky with that name, the other being Rho Puppis somewhat to the north. The Tureis in Puppis appears to have been the original bearer of the name (and indeed it seems logical that an emblem would be fixed to the ship's Stern, but less clear why it would lie in the middle of the Keel). The name comes from the Arabic for a 'shield' (specifically a small shield used as an emblem). In Greek and Latin this name translates as Aspidiske and Scutulum respectively, and both of these names are also used of Iota Carinae.

Physically Aspidiske is a white supergiant star, more than forty times the diameter of the Sun and generating nearly 6,000 times as much light energy, but this intense luminosity is offset by the star's great distance from the Solar System of more than 750 light years.* At a distance of 10 parsecs - the standard for calculating absolute magnitude - it would shine about as brightly as Venus in the night sky.

* Based on data from the Hipparcos satellite, Aspidiske has a parallax of 4.26, from which we can calculate a distance of 766 light years, ± 10%. Other sources suggest it may be a little nearer to the Sun at about 690 light years (on the inner edge of the Hipparcos error range) in turn implying that it may be slightly less intrinsically luminous (though still remaining a star in the supergiant class).


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