The North Star, which we are watching for centuries is also known as Polaris. Before the invention of the compass, the travellers used to depend on the star for the direction. Scientists earlier revealed that it is a part of a binary system which includes another dimmed star called Polaris B.
Even though we know much important information about North Star, we still have no idea how big or distant it is. But scientists said that they know how to find it out.
The famous star
The authors of a new paper said that "as we learn more, it is becoming clear that we understand less." It should be noted that there are a few ways astrophysicists to calculate the mass, age and distance of a star like Polaris.
One of this method includes a stellar evolution model, which was introduced in a new study, carried out by co-author Hilding R Neilson, an astrophysicist at the University of Toronto. By using this model the researchers would be able to study the brightness, colour and rate of pulsation of the star. The scientists can also use the data to figure out how big and bright it is and what stage of life it's in. After gathering these details, it will be easier to figure out how far away the star is, Neilson told Live Science.
Models which will help the scientists
As per the researcher, it should be noted that the models are precise for cepheids because their rate of pulsing is directly related to their brightness which makes it easy to calculate the distance to any of these stars. However, Neilson said the North Star is what is known as astrometric binary "which means you can actually see its companion going around it, sort of like a circle being drawn around Polaris. And that takes about 26 years."
The scientists haven't made yet a detail observations of a full circuit by Polaris B, but recently they noticed enough of the companion star in recent years which helped them to understand what the orbit looks like. As per Neilson, scientists can apply Newton's laws of gravity to measure the masses of the two stars. The data along with new Hubble Space Telescope "parallax" measurements would provide a calculation of the distance to the star. These measures reveal that it's about 3.45 times the mass of the sun.
The star system
It should be mentioned that the star system is weird in other ways. The calculation of Polaris B's age suggested that the star is much older than North Star which is quite unusual as in the binary system typically two stars are the same age. Along with the author of the study, Haley Blinn, an undergraduate student and researcher at the University of Toronto created a set of models of Polaris to see whether those models could reconcile all the data on the binary system but unfortunately, they could not succeed.
As per Neilson, Polaris is an especially difficult star to study which is located above the earth's the North Pole. It's outside the field of view of most telescopes which includes equipment for precisely measuring the star's properties are usually designed to study much fainter and more distant stars.
The recent research led the scientists to a new explanation which states that probably the bigger star of the system was once two stars and they collided together several million years ago. As per Neilson, such binary collision can rejuvenate stars. In the study, Neilson and Blinn wrote, "It is challenging to draw significant conclusions beyond the fact that Polaris continues to be an enduring mystery, and the more we measure the less we seem to understand."