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HD 157661

HD 157661 is the Henry Draper Catalogue designation for a likely triple star in the southern constellation of Ara. [1]

14 relations: Angular distance, Apparent magnitude, Ara (constellation), B-type main-sequence star, Bright Star Catalogue, Constellation, Durchmusterung, Henry Draper Catalogue, Hipparcos, Minute and second of arc, Monthly Notices of the Royal Astronomical Society, Parallax, Star system, Stellar classification.

Angular distance

In mathematics (in particular geometry and trigonometry) and all natural sciences (including astronomy, geophysics, etc.), the angular distance (angular separation, apparent distance, or apparent separation) between two point objects, as observed from a location different from either of these objects, is the size of the angle between the two directions originating from the observer and pointing towards these two objects.

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Apparent magnitude

The apparent magnitude (m) of a celestial object is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere.

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Ara (constellation)

Ara is a southern constellation situated between Scorpius and Triangulum Australe.

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B-type main-sequence star

A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars are extremely luminous and blue.

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Bright Star Catalogue

The Bright Star Catalogue, also known as the Yale Catalogue of Bright Stars or Yale Bright Star Catalogue, is a star catalogue that lists all stars of stellar magnitude 6.5 or brighter, which is roughly every star visible to the naked eye from Earth.

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Constellation

In modern astronomy, a constellation is a specific area of the celestial sphere as defined by the International Astronomical Union (IAU).

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Durchmusterung

In astronomy, Durchmusterung or Bonner Durchmusterung (BD), is the comprehensive astrometric star catalogue of the whole sky, compiled by the Bonn Observatory (Germany) from 1859 to 1903.

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Henry Draper Catalogue

The Henry Draper Catalogue (HD) is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the Henry Draper Extension Charts (HDEC), published from 1937 to 1949 in the form of charts, which gave classifications for 86,933 more stars.

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Hipparcos

Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993.

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Minute and second of arc

A minute of arc (MOA), arcminute (arcmin) or minute arc is a unit of angular measurement equal to one-sixtieth of one degree.

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Monthly Notices of the Royal Astronomical Society

Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.

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Parallax

Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.

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Star system

A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction.

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Stellar classification

In astronomy, stellar classification is the classification of stars based on their spectral characteristics.

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References

[1] https://en.wikipedia.org/wiki/HD_157661

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