Template: Polaris Star Token . Is the name of the star α Ursae Minoris (α UMi 1 UMi), the brightest of the constellation of the little bear , with apparent magnitude +1.97. It is also called the Polar Star or North Star because of its proximity to the celestial north pole .
Summary
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- 1 Name
- 2 Pole Star
- 3 Physical characteristics
- 4 Polaris and the Beatles
- 5 See also
- 6 References
Name
The name of Polaris comes from the Latin Stella Polaris , literally “Polar Star”. Given its proximity to the north pole, the star has received great attention since ancient times; Greek navigators called it Kynosoura or Cynosura , meaning “the dog’s tail.”
In China she was known by various names: Pih Keih , Ta Shin, and Tien Hwang Ta ti , “the Great Imperial Ruler of Heaven.” In northern India it received the title of Grahadhara , “the support of the planets.” It represented Dhruva and the Persian astronomer Al-Biruni pointed out that in his time – around 1000 BC. C. – represented Dhruva himself.
It was an object of worship, as it has been until recently for the Mandaeans of the Tigris and lower Euphrates . In Damascus , it received the title of Mismar , “the needle” or “the nail.”
Polar Star
Due to the precession of the equinoxes (due to the nutation movement of the Earth), the stars do not really remain fixed in the celestial vault . For this reason Polaris will not always be the star closest to the north pole, as it was not in the past. Polaris continues to approach our celestial north pole, and then gradually move away from it, and to which it will return within a complete cycle of precession, 25,780 years from now. Other stars, including Thuban (α Draconis) and Vega (α Lyrae) were the pole star in the past and will be again in the future.
To locate Polaris in the sky, simply extend the line determined by the stars Merak and Dubhe (β and α Ursae Majoris, respectively), finding the Pole Star at a distance equivalent to 5 times the separation distance of the two stars mentioned above. .
The equivalent of Polaris at the south pole is the star σ Octantis , hence called Polaris Australis . However, being a fifth magnitude star barely visible to the naked eye, in practice the constellation of the Southern Cross is used to locate the south celestial pole.
Physical characteristics
Polaris is a spectral-type yellow supergiant, its pulsations have stopped or are so small that they cannot be detected.
Polaris forms a star system with two companion stars. The brightest of these, Polaris B , is eighth magnitude and is located at 18 arc seconds ; is a main sequence star of the F3V type that is at least 2400 AU from the main star Polaris A. Closer to the latter is the other companion, Polaris C , initially discovered by spectroscopy and later resolved by the Space Telescope. Hubble . It is a yellow dwarf of type F7V that moves in an eccentric orbit at an average distance of 17 AU with respect to Polaris A and whose orbital period is 29.6 years. [1]
Polaris and The Beatles
On February 5, 2008, at 00:00 UTC, NASA broadcast The Beatles (John Lennon) song “Across The Universe” in the direction of the star Polaris. The transmission was made using a 70 m antenna at DSN’s Madrid Deep Space Communication Complex, located on the outskirts of Madrid, Spain. And it was done with an “X band” transmitter, providing the antenna with 18 kW.
This was done in order to celebrate the 40th anniversary of the song, the 45th anniversary of the Deep Space Network (DSN), and the 50th anniversary of NASA. The idea was conceived by Beatles historian Martin Lewis, who invited all Beatles fans to play the song as if it were going to be sent to a distant star. This is the second time that a piece of music has been intentionally broadcast to outer space (the first was the interstellar message: “1st Theremin Concert to Aliens”), and was approved by Paul McCartney, Yoko Ono, and Apple Records.
