{"id":65047,"date":"2024-10-29T11:45:23","date_gmt":"2024-10-29T11:45:23","guid":{"rendered":"http:\/\/a8f25d6a-690a-47c4-9495-49394a6e02bd"},"modified":"2024-10-29T12:39:37","modified_gmt":"2024-10-29T12:39:37","slug":"see-the-north-star-close-up-observations-of-polaris-reveal-newly-seen-detail-including-a-mottled-surface","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/see-the-north-star-close-up-observations-of-polaris-reveal-newly-seen-detail-including-a-mottled-surface\/","title":{"rendered":"See the North Star close-up. Observations of Polaris reveal newly-seen detail, including a mottled surface"},"content":{"rendered":"

<\/p>

By Ezzy Pearson\n <\/p>

Published: Tuesday, 29 October 2024 at 11:45 AM<\/p>

\n\n

The North Star, Polaris, may be a constant in the night sky, but the star is far from consistent. A set of observations has revealed it has a spotted surface.<\/p>

Polaris is well-known as the ‘North Star’, meaning you can use it to locate where ‘north’ is in the Northern Hemisphere night sky.<\/p>

The pointer stars of the Plough asterism, Dubhe<\/a> and Merak<\/a>, form a line that points to the North Star<\/a>, and this is a well-known way of locating it.<\/p>

You may have seen Polaris with the naked eye, but what about observing it through a powerful telescope?<\/p>

A group of astronomers decided to do just that, and get a closer look at the star’s surface.<\/p>

Polaris as it appears from Earth. Credit: Tom Elphick, Brighton, Sussex, UK <\/figcaption> <\/figure>

Polaris close-up<\/strong><\/h2>

Located 448 lightyears away, Polaris is the closest known Cepheid variable star to Earth.<\/p>

The rate at which a Cepheid varies is strongly linked to its luminosity, with fainter stars pulsing faster than bright ones.<\/p>

How bright a star appears in the sky depends on both its intrinsic brightness and how far away it is.<\/p>

This means astronomers can use the variability to measure a Cephid\u2019s true brightness and work out its distance from us across space<\/a>.\u00a0<\/p>

A team of astronomers used the CHARA Array at Mount Wilson, California<\/a>, to take advantage of Polaris\u2019s proximity and observe the fluctuating brightness of the star, finding it is 46 times brighter than the Sun.<\/p>

\"Image
Image of Polaris, the North Star, captured by the CHARA Array at Mount Wilson, California. Click to expand. Credit: Georgia State University \/ CHARA Array <\/figcaption> <\/figure>

The team also tracked the orbit of a companion star that orbits once every 30 years, allowing them to measure the mass of Polaris at 5.1 solar masses (previous estimates vary between 3.5 and 5 solar masses).<\/p>

They also imaged the surface of the star, revealing something unexpected.<\/p>

“The CHARA images revealed large bright and dark spots on the surface of Polaris that changed over time,” says\u00a0Gail Schaefer, director of the CHARA Array.\u00a0<\/p>

“We plan to continue imaging Polaris in the future,” says John Monnier, from University of Michigan, who took part in the study.<\/p>

“We hope to better understand the mechanism that generates the spots.”<\/p> <\/body><\/html>\n

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