Several centuries later, scientists suddenly found that there is something wrong with Polaris!

Polaris is already familiar. In fact, people have known Polaris for centuries. This bright star is very difficult to control and guide humans. It is Polaris, almost directly above the earth’s North Pole.

For travelers without a compass, it is a “guide” in the sky. In fact, it is the closest Cepheid variable on earth, and its diameter and brightness beat regularly.

Polaris is part of a binary system. It has a darker Sister star, Polaris B, which we can see revolving around the earth.

However, as the saying goes, we want to know less. As we learn more and more, it’s clear that we know less and less about Polaris. The problem with Polaris is that no one can agree on how big or how far it is.

Astrophysicists have several ways to calculate the mass, age, and distance of stars of the Arctic magnitude. One way, says astrophysicist Haiding Nielsen of the University of Toronto, is to model the evolution of stars.

Researchers can study the brightness, color and pulsation rate of the star, and use the data to determine how big and bright it is and what stage of its life it is in.

Once the details are clear, it’s not hard to see how far the star is from us, Nelson told life sciences. Once you know from earth how dark, how bright, how dark stars are, it’s easy.

These models are particularly accurate for Cepheids because their pulse rates are directly related to their brightness. This makes it easy to calculate the distance between these stars.

Astronomers are sure they understand the relationship. Cepheids have become an important tool to measure the distance of the whole universe. However, there are other ways to study Polaris, which is inconsistent with the stellar evolution model.

“Polaris is what we call an astrometric binary, which means you can see its companion spinning around it, sort of like drawing a circle around Polaris, which will take about 26 years,” Nelson said

Researchers have not yet made a detailed observation of the complete orbit of Polaris B, but they have seen enough companion stars in recent years to have a fairly detailed understanding of its orbit.

With this information, you can apply Newton’s law of gravity to measure the mass of two stars, Nielsen said, plus the new Hubble Space Telescope’s “parallax” measurements.

Another way to calculate the distance to the star makes the mass and distance of Polaris very accurate. These measurements show that its mass is about 3.45 times that of the sun, with an error of 0.75 times.

That’s much less than the mass you get from the stellar evolution model, which is about seven times the mass of the sun. Stellar systems are strange in other ways, too.

Calculations of the age of Polaris b show that the star is much older than its big brother, which is unusual for binary systems. In general, the two stars are the same age.

Together with undergraduate and researcher Haley brin of the University of Toronto, Nielsen built a huge Polaris model to see if the models were consistent with all known system data. They can’t.

‘one possibility is that at least one measurement is wrong,’ the researchers wrote. Nelson said Polaris is a very difficult star to study.

It is located above the north pole of the earth, out of the view of most telescopes. Telescopes with the necessary equipment to accurately measure the properties of stars are often designed to study darker and farther stars. Polaris is too bright for those instruments.

In fact, they turned a blind eye to it. But the researchers do believe the data are reliable, and there is no obvious reason to doubt the information, Nielsen said.

These findings give Nelson and Brin another strange explanation: perhaps the main stars in the Polaris system are two stars that collided millions of years ago. Such a binary collision can regenerate stars and absorb extra material, making stars look like “passing through the fountain of youth,” Nelson said.

The stars produced by binary collisions do not fully conform to the stellar evolution model, which can explain the differences found on Polaris.

“It’s an unlikely scenario, but it’s not impossible.” The researchers wrote.

So far, no solution is completely satisfactory. “The north pole star and Nelson wrote:” is still an eternal mystery. The more we measure, the less we seem to understand. Moreover, it’s hard to come to meaningful conclusions. “

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