2024-08-22 00:07:42
The Polar Star is not a single star, that is, it is a title given to several stars due to the axial oscillation of our planet. The current holder of the title is Estrela do Norte.
Also known as Polaris, mankind has a deep knowledge of it, depicted in pictures for centuries, as well as photographed by astronomers and observed by scientific instruments.
But, for the first time, the star was taken in high resolution. The CHARA Array, located on Mount Wilson, in California (USA). It works telescopes CHARA together, as recalls the space.com.
The light data received at a central facility is combined to provide a complete and clear picture of what is being observed. Together, the telescopes “form” only one, with a diameter of 330 m. Therefore, the angular resolution is, above all, great.
In analyzes of images of Polaris captured by CHARA between 2016 and 2021, scientists detected previously unknown features, such as recognizable points on its surface, similar to the Sun’s sunspots.
Em statementGail Schaefer, director of CHARA, said: “CHARA images showed large bright and dark spots on the surface of Polaris that changed over time.”
Details on the surface of the North Star
- The discovery is surprising, starting with the fact that the star is just any star;
- The North Star is known as the variable Cepheid, which means it shines and flares periodically;
- Polaris shines, especially speaking, more and less according to a cycle of four days;
- Finding Cepheids is great for scientists because they are used to measure cosmic distances. Observing the change in brightness of a Cepheid during its cycle can reveal its true brightness.
An ordinary star is not very reliable for measurements, as it may be very distant, very small, strangely faint for some other reason, or even faint during observation.
Because of this, the high-resolution images of Polaris are the first “insight into what the surface of a Cepheid variable looks like”. But the team found other points that were just as interesting.
Read more:
Polaris and its companion, seen by Hubble in 2006 (Image: NASA, ESA, N. Evans [Harvard-Smithsonian CfA] e H. Bond [STScI])What does Polaris look like?
Polaris is about 46 times the size of the Sun and is more than 400 light years from Earth. She goes around the Universe with two other stars. Because of this, CHARA’s original purpose was to map the orbits of stars orbiting the North Star every 30 years.
Not only is such a star floating very close to Polaris, but it is also very faint. It was discovered in 2005 thanks to the Hubble Space Telescope.
The small separation and large brightness contrast between the two stars makes it extremely challenging to resolve the binary system during its closest approach.
Nancy Evans, team leader at the Center for Astrophysics, Harvard & Smithsonian, in a statement
Therefore, the team went further and brought with them more instruments to help the investigations, such as a trout interferometer from the Apache Point Observatory, in New Mexico (USA).
The scientists were able to confirm some information about Polaris, such as its size, suggesting that it could be about five times more massive than our Sun, heavier than the researchers imagined.
This discovery is extremely important, because very few of the Cepheids have had their mass determined, as Evans said. Science News. “The mass combined with distance indicates that Cepheid is more luminous than predicted for this mass from evolutionary trajectories,” wrote the authors of the study, published this Tuesday (20) in The Astrophysical Journal.
“We plan to continue photographing Polaris in the future. We hope to better understand the mechanism that generates the spots on the surface of Polaris,” said John Monnier, professor of astronomy at the University of Michigan and co-author of the study, in the statement.
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