How many actual stars are Polaris? I am getting conflicting accounts everywhere. I heard astronomers saying Polaris is a 3-star system. Some say they are binary but are optical-doubled with a 3rd.

Phil Plait a renowned astronomer wrote in his book Bad Astronomy that Polaris is sextuple star system. 



The above text reads 


  ... but due to its proximity to the NCP it has taken on the popular name of Polaris. The star itself is actually rather interesting; it's really a multiple star consisting of at least six stars in orbit around each other.


While in his Crash Course Astronomy Series He said Polaris was a Pentuple star system.

Now, I am not saying Phil is doing anything wrong. I am actually a fan of him, enjoyed reading the books he authored. He may have said one or the other by mistake. I tried asking him this question, it does not look like there is an effective way to submit him an Errata or ask him questions like these.

So my question is, how many stars are Polaris and are they all gravitationally bound to each other or some of them are just Optically grouped?
Polaris consists of multiple stars, 

α UMi Aa is the main star. It is a supergiant, and a cepheid variable. α UMi Ab and α UMi B are smaller (but still larger than the sun) and both are in orbit with α UMi Aa, (the former is close in, the latter is further out).

There are two further stars: α UMi C and D. These stars are thought to have formed before α UMi Aa, and so are not considered to be physically associated with α UMi A. There are other stars that appear nearby, one might be physically associated: J021006.2+891626 J021454.3+890852 are their catalogue numbuers. They are faint, but appear to be the same age as Polaris.

In conclusion, Polaris is known to have 3 stars: Aa, Ab and B. The stars C and D are not physically related to Polaris. There may be one or two more stars that are distant dwarfs and may share Polaris's orbit.

Reference http://iopscience.iop.org/article/10.1088/0004-6256/139/5/1968