The brightest star that we can see in the night sky has been named Sirius, an ancient Greek word for “glowing”. It’s one of the closest stars to earth, about 8.5 light years away, and we can look forward to it getting brighter for the next 60,000 years as it inches ever closer to us. When the conditions are right, this star can be seen even in daylight.
It was in 1844, however, when this bright pinpoint of light was determined to be a binary star. That means the light we see is, in fact, produced by a pair of burning gas balls so close together that it seems as one. Sirius A is a big bright star, while Sirius B is a tiny white dwarf, which is a late stage star that has nearly burnt out and collapsed into a super dense ball. A teaspoon of white dwarf star material would weigh about the same as a locomotive.
The two make up a binary star system because they orbit around each other at about the same distance as Uranus orbits around the Sun. That’s close enough to be tangled up in each others gravitational fields. Some binary stars are so close that they actually pull on the gas like the moon pulls on the ocean tides. Matter is ripped free of it’s gravitational bonds creating a stream of “star juice” between the two masses.
Thanks to Kepler’s Laws of Planetary Motion physicists have been able to look at the orbits of binary stars, which from our viewpoint is little more than a wobble, and reverse engineer the precise details of their mass and density. Combining that with a stars spectral signature, the peculiarities of the light it radiates, we’ve been able to learn a lot about the composition of stars twinkling from afar.
With improvements in both our telescopes and our understanding we’ve been able to determine that approximately 85 % of the stars in our own neighbourhood, the Milky Way galaxy, are binary pairs, or even larger multiple star systems. It seems our Sun is the odd one out, all by its lonesome.
Be nice to our Sun. After all, we’re made of the same stuff.