{"id":57893,"date":"2024-05-01T08:30:17","date_gmt":"2024-05-01T08:30:17","guid":{"rendered":"http:\/\/0a312106-1a84-4c2f-b03c-fea2159dd164"},"modified":"2024-05-01T09:08:21","modified_gmt":"2024-05-01T09:08:21","slug":"pherkad-is-a-giant-star-15-times-bigger-than-our-sun-that-never-sets-find-out-how-to-see-it-in-the-little-bear","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/pherkad-is-a-giant-star-15-times-bigger-than-our-sun-that-never-sets-find-out-how-to-see-it-in-the-little-bear\/","title":{"rendered":"Pherkad is a giant star 15 times bigger than our Sun that never sets. Find out how to see it in the Little Bear."},"content":{"rendered":"

How to find the circumpolar star in Ursa Minor. <\/p>

By Pete Lawrence\n <\/p>

Published: Wednesday, 01 May 2024 at 08:30 AM<\/p>

\n\n

Lying just 18\u00b0 from the north celestial pole, Pherkad is circumpolar<\/a> from the UK and never sets.<\/p>

It\u2019s a bright, giant of spectral class<\/a> A3 III and sits 487 lightyears from the Sun. Pherkad is 15 times larger than the Sun and 1,100 times more luminous.<\/p>

With a mass almost five times that of the Sun, Pherkad is likely close to 100 million years old.\u00a0<\/p>

Pherkad is a circumpolar star in the constellation Ursa Minor. Click to expand. Credit: Pete Lawrence<\/figcaption><\/figure>
**How Pherkad compares to its constellation companions<\/strong><\/h2>**Most people know what the Plough<\/a> or Saucepan looks like, a distinctive seven-star pattern that is part of the Great Bear, Ursa Major<\/a>.<\/p>
The Little Bear, Ursa Minor<\/a>, similarly has seven stars, three being in a curve starting from Polaris (Alpha (\u03b1) Ursae Minoris) that joins to a box shape.<\/p>
As with the Plough, the pattern represents the little bear\u2019s rump and tail, but unlike the Great Bear, the rest of the creature is not well represented.\u00a0<\/p>
$\"Chart$
Click to expand.<\/figcaption><\/figure>
The box\u2019s two corner stars located closest to Polaris are fairly dim and easily lost from a site with medium light pollution.<\/p>
These are mag. +4.3 Zeta (\u03b6) and mag. +4.9 Eta (\u03b7) Ursae Minoris.<\/p>
The other two are brighter: mag. +2.1 Kochab (Beta (\u03b2) Ursae Minoris) and mag. +3.0 Pherkad (Gamma (\u03b3) Ursae Minoris).<\/p>
Together, Kochab and Pherkad are known enigmatically as the Guardians of the Pole.<\/p>
$\"Star$
Star Pherkad in Ursa Minor. Credit WikiSky \/ DSS2<\/figcaption><\/figure>
**A variable star<\/strong><\/h2>**Pherkad rotates at 180km\/s and is a variable star<\/a>, but exhibits an odd form of variability.<\/p>
Its brightness can change by less than a tenth of a magnitude over just a few hours.<\/p>
The cause of this isn\u2019t well known.<\/p>
Originally it was classed as a shell star, which is one with a circumstellar disc of gas around its equator, but this seems to have disappeared.<\/p>
***This guide appeared in the May 2024 issue of BBC Sky at Night Magazine.<\/em><\/strong><\/p> <\/body><\/html>\n***
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