Delta Lyrae cluster is a sparse open cluster of stars located about 1,220

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s away in the northern

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

of Lyra. Centered on the member star Delta² Lyrae for which it is named. This cluster was first suspected in 1959 by American astronomer Charles B. Stephenson, then was later concluded not to exist by German astronomer Werner Bronkalla in 1963. However, subsequent photometric observations at the Palomar and Mount Wilson observatories led American astronomer

Olin J. Eggen Olin Jeuck Eggen (July 9, 1919 – October 2, 1998) was an American astronomer. Biography Olin Jeuck Eggen was born to Olin Eggen and Bertha Clare Jeuck in the village of Orfordville in Rock County, Wisconsin. Both of his parents were of Norw ...

to demonstrate that there was an actual cluster, at least for the observed stars down to absolute magnitude +5.5. Eggen's study found at least 33 members. The cluster has a visual magnitude of 3.8 and spans an angular diameter of 20 arc minutes. The tidal radius of the cluster is and it has an estimated combined mass of 589 times the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...

. Based upon its estimated age and motion through space, it may be associated with the Gould Belt. It includes an Algol variable star, BD+36° 3317, discovered in 2007 from Spain: this is a

spectroscopic binary A binary star is a system of two star, stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separa ...

star system that undergoes regular eclipses because the orbital plane is nearly aligned with the line of sight to the Earth.

References

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See also

References