Properties
This star is larger than the Sun, with about two times its mass and almost nine times its radius. Once an A-type main sequence star, Pollux has exhausted the hydrogen at its core and evolved into a giant star with a stellar classification of K0 III. The effective temperature of this star's outer envelope is about 4,666 K, which lies in the range that produces the characteristic orange hue of K-type stars. Pollux appears to be rotating at a leisurely rate, with a protected rotational velocity of 2.8 km s–1. The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is somewhat uncertain, with estimates ranging from 85% to 155% of the Sun's abundance.
Evidence for a low level of magnetic activity came from the detection of weak X-ray emission using the ROSAT orbiting telescope. The X-ray emission from this star is about 1027 erg s–1, which is roughly the same as the X-ray emission from the Sun. A magnetic field with a strength below 1 Gauss has since been confirmed on the surface of Pollux; one of the weakest fields ever detected on a star. The presence of this field suggests that Pollux was once an Ap star with a much stronger magnetic field.
Read more about this topic: Pollux (star)
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