AB DORADUS

'AB Doradus' is a pre-main sequence trinary star system in the constellation Dorado. The primary is a flare star that shows periodic increases in activity.
The primary star in this system spins at a rate 50 times that of the Sun, and consequently has a strong magnetic field.^[1] It has a greater number of star spots than does the Sun. These can cause the luminosity of the star to appear to vary over each orbital cycle. Measurements of the spin rate of this star at its equator have shown that it varies over time due to the effect of this magnetic field.^[2]
The primary has three companions. The binary star 'AB Doradus B' orbits the primary at an average distance of 135 astronomical units (AUs). 'AB Doradus C', is a close-in companion that orbits the primary at a distance of 2.3 AU, and has an orbital period of 11.75 years. The later star is among the lowest mass stars ever found. At an estimated mass 93 times Jupiter's, it is near the limit of 75-83 Jupiter masses below which it would be classified as a brown dwarf.^[3]
This system is a member of the like-named 'AB Doradus moving group', a loose stellar association of about 30 stars that are all moving in the same general direction and having approximately the same age.
^[4] It is likely that all of these stars formed in the same giant molecular cloud.

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References

External links

★ HD 36705 -- Rotationally variable Star

★ 4C05660

★ Detecting Extra-solar Planets