A double star is when two stars appear close to each other as seen from Earth. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001
There are two kinds of double star: visual binaries and optical binaries. Visual binaries are considered to be a true binary star system and lie close enough together in space to interact gravitationally such that the stars orbit each other. A binary star is a Star system consisting of two Stars orbiting around their Center of mass. Optical binaries (aka optical doubles), on the other hand, are two stars that only appear to be close together, and are actually separated by a great distance in space and are not gravitationally bound to each other.
Optical doubles are distinguished from binary stars by observing them for a long period of time, usually years. If the relative motion looks linear, it may be safely assumed that the motion is due to proper motion alone and that they are an optical double. The proper motion of a Star is the measurement of its change in position in the sky over time after Improper motions are accounted for In the case of a true binary, the position angle changes progressively and the distance between the two stars oscillates between a maximum and minimum.
The first recorded discovery of a true binary star system was by Giovanni Battista Riccioli in 1650, when he found Mizar (ζ Ursae Majoris) was a double star. A binary star is a Star system consisting of two Stars orbiting around their Center of mass. Giovanni Battista Riccioli ( April 17 1598 – June 25 1671) was an Italian Astronomer. Since that time, the search for double stars has been carried out thoroughly and every star down to the 10th stellar magnitude has been examined. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value At least 1 in 18 stars in the northern half of the sky which are as bright as 9. 0 magnitude is a close double star visible with a 36-inch telescope. A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation.
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Examples
Visual binary
Optical binary
Undetermined status
- Alpha Centauri system (A and B) and Proxima Centauri (= Alpha Centauri C?) Generally considered likely. Sirius is the brightest star in the night sky with a visual Apparent magnitude of &minus1 This article is about the star Procyon is also the mammalian genus to which raccoons belong Physical Properties Acrux (α Cru / α Crucis / Alpha Crucis is the brightest star in Constellation Crux, the Southern Cross and Algol (β Per / Beta Persei known colloquially as the Demon Star, is a bright Star in the Constellation Perseus. Winnecke 4 (also known as Messier 40 or WNC 4) is a Double star in the constellation Ursa Major. Alpha Centauri (α Centauri / α Cen also known as Rigil Kentaurus, Rigil Kent, or Toliman, is the brightest Star in the southern Constellation Proxima Centauri ( Latin la ''proximus proxima proximum'' meaning 'next to' or 'nearest to' is a Red dwarf Star approximately 4
- Castor system (Aa/Ab/Ba/Bb and YY Geminorum (= Castor Ca/Cb?) Generally considered likely. Castor (α Gem / α Geminorum / Alpha Geminorum is the second brightest star in the Constellation Gemini and one of the brightest stars in the
- Mizar system (Aa/Ab/Ba/Bb) and Alcor (= Mizar C?) Generally considered unlikely. ALCOR is an early computer language definition created by the ALCOR Group, a consortium of universitites research institutions and manufacturers in Europe and the USA which
Dictionary
double star
-noun
- (astronomy) Two stars which form a stellar system, such that they orbit the point of equilibrium of their gravitational fields; a binary star.
- (astronomy) Two stars that appear to be one when seen with the naked eye, either because they orbit one another (binary stars) or happen to be in the same line of sight even though they are separated by a great distance (optical binaries).
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