Mirfak

In Greek mythology, Perseus was a hero — he rescued the princess Andromeda from a nasty sea monster. And the brightest star of the constellation that depicts Perseus befits a hero: It’s big, heavy, and bright.
Mirfak is far more impressive than the Sun: seven or eight times heavier, about 60 times wider, and about 5,000 times brighter. That makes it easy to see even though it’s more than 500 light-years away.
Yet there’s more to Mirfak than meets the eye — perhaps including a companion star.
Mirfak produces a lot of X-rays. That’s a bit of a surprise for a star of its temperature and stage of life. That could mean that Mirfak is an oddball — that some unknown mechanism is causing it to produce the X-rays. But it also could mean that it has an unseen companion — a smaller star with a hot outer atmosphere, like the Sun’s corona.
Searches for such a star have turned up empty — so far. But the system is so far away, and Mirfak itself is so bright, that a companion easily could be hidden in