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18947847. LC Class. PZ7.L9673 Nu 1989. Number the Stars is a work of historical fiction by the American author Lois Lowry about the escape of a family of Jews from Copenhagen, Denmark, during World War II. The story revolves around ten-year-old Annemarie Johansen, who lives with her mother, father, and sister Kirsti in Copenhagen in 1943.
Stellar classification. In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines.
AR Lacertae is a frequently-studied [8] triple star system in the northern constellation of Lacerta, abbreviated AR Lac. This variable star system is the prototype for "detached systems of the AR Lacertae type". [3] It is dimly visible to the naked eye with a combined peak apparent visual magnitude of 6.08. [3]
Artist's impression of the orbits of HD 188753, a triple star system. A star system or stellar system is a small number of stars that orbit each other, [1] bound by gravitational attraction. A large group of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.
Absolute magnitude is defined as the apparent magnitude that a star or object would have if it were observed from a distance of 10 parsecs (33 light-years; 3.1 × 10 14 kilometres; 1.9 × 10 14 miles). Therefore, it is of greater use in stellar astrophysics since it refers to a property of a star regardless of how close it is to Earth.
Only a tiny minority of known stars have proper names; all others have only designations from various catalogues or lists, or no identifier at all. Hipparchus in the 2nd century BC enumerated about 850 naked-eye stars. Johann Bayer in 1603 listed about twice this number. Only in the 19th century did star catalogues list the naked-eye stars ...
Polaris is the brightest star in the constellation of Ursa Minor (upper right). Big Dipper and Ursa Minor in relation to Polaris. A view of Polaris in a small telescope. Polaris B is separated by 18 arc seconds from the primary star, Polaris A. A 4-day time lapse of Polaris illustrating its Cepheid type variability.
Additionally, astronomers have found 6 white dwarfs (stars that have exhausted all fusible hydrogen), 21 brown dwarfs, as well as 1 sub-brown dwarf, WISE 0855−0714 (possibly a rogue planet). The closest system is Alpha Centauri, with Proxima Centauri as the closest star in that system, at 4.2465 light-years from Earth.