τ Boötis (τ Boo / Tau Boötis) is a 4th magnitude star in the constellation of Boötes. The system is a binary. The primary component is a yellow-white dwarf (spectral type F7 V) and secondary is a dim red dwarf (spectral type M2 V).
The system is relatively nearby, distance being about 51 light years. The primary star should be easily visible to the unaided eye under dark skies.
In 1997 a planet, designated as Tau Boötis Ab was discovered orbiting the primary star. There is also some indications of another, more distant planet orbiting the star.
Tau Boötis A
The primary star, Tau Boötis A is a yellow-white dwarf. It is 20% more massive than our Sun and thus is somewhat brighter and hotter. It has a radius 1.9 times solar, and is probably about 1300 million years old. Since it is more massive than the Sun, its lifespan is shorter being less than 6000 million years.
It is also listed as a suspected variable star. However, the star is not variable.
Tau Boötis B
Tau Boötis B is a dim red dwarf orbiting the primary star at a distance of 240 AU. One orbit around the primary would take thousands of years to complete.
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