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Based upon an annual parallax shift of 0.00632 arcseconds, [1] the distance to this system is roughly 520 light years. This is a single-lined spectroscopic binary system, [9] which means that only the absorption line features of one of the components can be distinguished.
This number is likely much higher, due to the sheer number of stars needed to be surveyed; a star approaching the Solar System 10 million years ago, moving at a typical Sun-relative 20–200 kilometers per second, would be 600–6,000 light-years from the Sun at present day, with millions of stars closer to the Sun.
The parsec (3.26 light-years) is defined as the distance for which the annual parallax is 1 arcsecond. Annual parallax is normally measured by observing the position of a star at different times of the year as Earth moves through its orbit. The angles involved in these calculations are very small and thus difficult to measure.
This is a list of the nearest supergiant stars to Earth, located at a distance of up to 1,100 light-years (340 parsecs) from Earth. Some of the brightest stars in the night sky, such as Rigel and Antares, are in the list.
The use of the parsec as a unit of distance follows naturally from Bessel's method, because the distance in parsecs can be computed simply as the reciprocal of the parallax angle in arcseconds (i.e.: if the parallax angle is 1 arcsecond, the object is 1 pc from the Sun; if the parallax angle is 0.5 arcseconds, the object is 2 pc away; etc.).
HD 141569 is an isolated [5] Herbig Ae/Be star [6] of spectral class A2Ve [7] approximately 364 light-years away in the constellation of Libra. The primary star has two red dwarf companions (orbiting each other) at about nine arcseconds. In 1999, a protoplanetary disk was discovered around the star.
The Andromeda Galaxy is approximately 2.5 million light-years away. 3 × 10 6 ly: The Triangulum Galaxy , at about 3 million light-years away, is the most distant object visible to the naked eye. 5.9 × 10 7 ly: The nearest large galaxy cluster, the Virgo Cluster, is about 59 million light-years away. 1.5 × 10 8 – 2.5 × 10 8 ly
The first is the direction of the proper motion on the celestial sphere (with 0 degrees meaning the motion is north, 90 degrees meaning the motion is east, (left on most sky maps and space telescope images) and so on), and the second is its magnitude, typically expressed in arcseconds per year (symbols: arcsec/yr, as/yr, ″/yr, ″ yr −1) or ...