61 Cygni – a Binary Star System in the Constellation Cygnus

61 Cygni was christened the “Flying Star” in 1792 by Giuseppe Piazzi (1746-1826) for its unusually large proper motion. It is a binary star system in the constellation Cygnus, consisting of a pair of K-type dwarf stars that orbit each other in a period of about 659 years. It’s a binary star, whose double nature cannot be seen with the eye alone. Of apparent magnitude 5.20 and 6.05, respectively, they can be seen with binoculars in city skies or with the naked eye in rural areas without photo pollution. It is, however, among the most important of stars visible without optical aid. There is a pair of K-type dwarf stars in the single point of light we see as 61 Cygni. They orbit each other for a period of about 659 years.

61 Cygni is a variable and multiple main-sequence stars in the constellation of Cygnus. Because of its relative faintness, 61 Cygni should be visible only from locations with dark skies, while it is not visible at all from skyes affected by light pollution.

61 Cygni is the first star whose distance from Earth was measured. 61 Cygni first attracted the attention of astronomers when its large proper motion was first demonstrated by Giuseppe Piazzi in 1804. 61 Cygni’s motion across our sky can’t be easily detected with the eye alone over the span of a human lifetime. In 1838, Friedrich Bessel measured its distance from Earth at about 10.4 light-years, very close to the actual value of about 11.4 light-years; this was the first distance estimate for any star other than the Sun, and the first star to have its stellar parallax measured. Astronomers discovered its large proper motion via careful observation. Its apparent position would shift by an amount equal to the width of the full moon in only 150 years.

Although it’s not bright, it moves exceptionally rapidly against the background of more distant stars. Among all-stars or stellar systems listed in the modern Hipparcos Catalogue, 61 Cygni has the seventh-highest proper motion and the highest among all visible stars or systems. It moves relatively rapidly in front of the fixed stars because 61 Cygni is relatively near Earth. It is one of the closest stars to our Sun and Earth.

61 Cygni’s position is RA: 21h 06m 51s, dec: +38° 44′ 29″. Over the course of the twentieth century, several different astronomers reported evidence of a massive planet orbiting one of the two stars, but recent high-precision radial velocity observations have shown that all such claims were unfounded. Its motion reveals its nearness to Earth. No planets have been confirmed in this stellar system to date.

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