The period, roughly 4 days, has also changed over time. It has steadily increased by around 4.5 seconds per year except for a hiatus in 1963–1965. This was originally thought to be due to secular redward (lower temperature) evolution across the Cepheid instability strip, but it may be due to interference between the primary and the first- overtone pulsation modes. [20] [29] [30] Authors disagree on whether Polaris is a fundamental or first-overtone pulsator and on whether it is crossing the instability strip for the first time or not. [12] [30] [31]

Wyller, A. A. (December 1957). "Parallax and orbital motion of spectroscopic binary Polaris from photographs taken with the 24-inch Sproul refractor". Astronomical Journal. 62: 389–393. Bibcode: 1957AJ.....62..389W. doi: 10.1086/107559. Star of the North is one to look out for when it’s published in early May. Original, cleverly plotted and easy to read. After a brilliant set up it’s action all the way to the finish. As the strands of the story come together the plot reaches a nail biting and powerful conclusion.” - Nudge-Book.com, http://nudge-book.com/blog/2018/02/star-of-the-north-by-d-b-john/ Cayrel de Strobel, G.; Soubiran, C.; Ralite, N. (2001). "Catalogue of [Fe/H] determinations for FGK stars: 2001 edition". Astronomy and Astrophysics. 373: 159–163. arXiv: astro-ph/0106438. Bibcode: 2001A&A...373..159C. doi: 10.1051/0004-6361:20010525. S2CID 17519049. a b Neilson, H. R.; Engle, S. G.; Guinan, E.; Langer, N.; Wasatonic, R. P.; Williams, D. B. (2012). "The Period Change of the Cepheid Polaris Suggests Enhanced Mass Loss". The Astrophysical Journal. 745 (2): L32. arXiv: 1201.0761. Bibcode: 2012ApJ...745L..32N. doi: 10.1088/2041-8205/745/2/L32. S2CID 118625176.

The North Star: Polaris

Extraordinary … smart, sophisticated, suspenseful – and important. If you try one new thing this year, make it Star of the North.”— Lee Child a b c d Samus, N. N.; Kazarovets, E. V.; etal. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode: 2017ARep...61...80S. doi: 10.1134/S1063772917010085. S2CID 125853869. Astronomers want to determine the mass of Polaris accurately because it is the nearest Cepheid variable star, a type of star that pulsates radially, varying in both diameter and temperature producing changes in brightness with a well-defined stable period and amplitude. It is estimated that Polaris’ distance is roughly 430 light years away. The single point of light that we see as Polaris is actually a triple star system; three stars orbiting a common center of mass. A thrilling tale of abduction and escape in North Korea...highly entertaining...S tar of the North builds to a gripping climax. Washington Post

That’s the spot we’d be looking at if we were to take Earth’s north pole and stretch it way off into space: Polaris is almost exactly due north. Original, cleverly plotted and easy to read...After a brilliant set up it’s action all the way to the...nail biting and powerful conclusion. The Nudge In traditional Lakota star knowledge, Polaris is named "Wičháȟpi owáŋžila". This translates to "The Star that Sits Still". This name comes from a Lakota story in which he married Tapun San Win "Red Cheeked Woman". However she fell from the heavens, and in his grief he stared down from "waŋkátu" (the above land) forever. [52] John] tells his exciting story well and is a fine writer of action scenes. But what really makes the book unmissable is its portrayal of everyday life for ordinary people in North Korea Charlotte Heathcote, Sunday Express The ultimate goal is the get an accurate mass for Polaris by measuring the motion of the companion, Polaris Ab in its orbit.a b Ridpath, Ian, ed. (2004). Norton's Star Atlas. New York: Pearson Education. p. 5. ISBN 978-0-13-145164-3. Around 4800 years ago Thuban ( α Draconis) lay a mere 0°.1 from the pole. Deneb ( α Cygni) will be the brightest star near the pole in about 8000 years' time, at a distance of 7°.5. The ancient name of the constellation Ursa Minor, Cynosura (from the Greek κυνόσουρα "the dog's tail"), [47] became associated with the pole star in particular by the early modern period. An explicit identification of Mary as stella maris with the polar star ( Stella Polaris), as well as the use of Cynosura as a name of the star, is evident in the title Cynosura seu Mariana Stella Polaris (i.e. "Cynosure, or the Marian Polar Star"), a collection of Marian poetry published by Nicolaus Lucensis (Niccolo Barsotti de Lucca) in 1655. [ citation needed] An informed look at the oppression, corruption, and widespread suffering under Kim Jong-il.” — Kirkus

Roemer, Elizabeth (May 1965). "Orbital Motion of Alpha Ursae Minoris from Radial Velocities". Astrophysical Journal. 141: 1415. Bibcode: 1965ApJ...141.1415R. doi: 10.1086/148230. In about 13,000 years from our current date, the precession of the rotation axis will mean that the bright star Vega will become the North Star.By the 5th century, Macedonian historian Joannes Stobaeus described the North Star as always visible, so it eventually became a tool for navigation. During the Age of Exploration in the 15th through 17th centuries, it was used to tell which way was north. By watching the motion of Polaris A’s companion star, Polaris Ab, astronomers expect to learn not only the stars’ orbits but also their masses. Measuring the mass of a star is one of the most difficult tasks.