It's just a case of a journalist not understanding what they are reading, and then making a complete hash of it when they try to paraphrase it.
The facts in the side box entitled "THE BRIGHTEST STAR SIRIUS" are all factually correct. (They may have been copied from Wikipedia:
https://en.wikipedia.org/wiki/Sirius )
The following factually-correct statement appears in the fact box:
Sirius is the brightest 'star' in the night sky.
In fact it is a binary system of a white main-sequence star called Sirius A, and a faint white dwarf, Sirius B.
This has been paraphrased in the adjacent body text by erroneously adding one critical word - "because":
Sirius is so bright because it is in fact a binary star system, two stars orbiting each other.
(All of which doesn't detract from the fact that the photos which are the subject of the article are gorgeous!)