Delta Lyrae cluster is a sparse

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

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 of

Lyra Lyra (; Latin for lyre, from Greek ''λύρα'') is a small constellation. It is one of the 48 listed by the 2nd century astronomer Ptolemy, and is one of the modern 88 constellations recognized by the International Astronomical Union. Lyra was ...

. 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 Charles Bruce Stephenson (February 9, 1929 – December 3, 2001) was an American astronomer. He was born on a ranch in Little Rock, Arkansas, the only son of Chauncey Elvira Stephenson and Ona Richards. During his youth he made a telescope and w ...

, then was later concluded not to exist by German astronomer Werner Bronkalla in 1963. However, subsequent photometric observations at the

Palomar Palomar may refer to: Places * Any of several locations in San Diego County, California: ** Palomar Mountain ** Palomar Observatory, located on Palomar Mountain ** Palomar College in San Marcos, California ** Palomar Medical Center in Escondido, C ...

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 Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it we ...

+5.5. Eggen's study found at least 33 members. The cluster has a

visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

of 3.8 and spans an

angular diameter The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it i ...

of 20

arc minute A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The nau ...

s. The

tidal radius A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member ...

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 of ...

. Based upon its estimated age and motion through space, it may be associated with the

Gould Belt The Gould Belt is a local, partial ring of stars in the Milky Way, about 3,000 light-years long, tilted away from the galactic plane by about 16–20 degrees. It contains many O- and B-type stars, amounting to the nearest star-forming regio ...

. It includes an

Algol variable Algol variables or Algol-type binaries are a class of eclipsing binary stars that are similar to the prototype member of this class, β Persei (Beta Persei, Algol). An Algol binary is a system where both stars are near-spherical such that ...

star, BD+36° 3317, discovered in 2007 from Spain: this is a spectroscopic binary star system that undergoes regular eclipses because the

orbital plane The orbital plane of a revolving body is the geometric plane in which its orbit lies. Three non-collinear points in space suffice to determine an orbital plane. A common example would be the positions of the centers of a massive body (host) an ...

is nearly aligned with the

line of sight The line of sight, also known as visual axis or sightline (also sight line), is an imaginary line between a viewer/observer/spectator's eye(s) and a subject of interest, or their relative direction. The subject may be any definable object taken n ...

to the Earth.

References

{{reflist, refs= {{citation , last1=Eggen , first1=O. J. , title=Photometric evidence for the existence of a delta Lyrae cluster , journal=Astrophysical Journal , volume=152 , page=77 , date=April 1968 , doi=10.1086/149525 , bibcode=1968ApJ...152...77E , postscript=. {{Citation , last1 = Wu , first1 = Zhen-Yu , last2 = Zhou , first2 = Xu , last3 = Ma , first3 = Jun , last4 = Du , first4 = Cui-Hua , display-authors = 1 , title = The orbits of open clusters in the Galaxy , journal =

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. It has been in continuous existence since 1827 and publishes letters and papers reporting origina ...

, volume = 399 , issue = 4 , pages = 2146–2164 , date=November 2009 , arxiv = 0909.3737 , bibcode = 2009MNRAS.399.2146W , doi = 10.1111/j.1365-2966.2009.15416.x , s2cid = 6066790 , postscript = . {{citation , display-authors=1 , last1=Özdarcan , first1=O. , last2=Sipahi , first2=E. , last3=Dal , first3=H. A. , title=BD+36 3317: An algol type eclipsing binary in Delta Lyrae cluster , journal=New Astronomy , volume=17 , issue=5 , pages=483–487 , date=July 2012 , doi=10.1016/j.newast.2011.12.002 , bibcode=2012NewA...17..483O , postscript=. , arxiv = 1207.0194 , s2cid=118588705 {{citation , display-authors=1 , last1=Piskunov , first1=A. E. , last2=Schilbach , first2=E. , last3=Kharchenko , first3=N. V. , last4=Röser , first4=S. , last5=Scholz , first5=R.-D. , title=Tidal radii and masses of open clusters , journal=Astronomy and Astrophysics , volume=477 , issue=1 , pages=165–172 , date=January 2008 , doi=10.1051/0004-6361:20078525 , bibcode=2008A&A...477..165P , postscript=. , doi-access=free {{citation , first1=Craig , last1=Crossen , first2=Gerald , last2=Rhemann , title=Sky Vistas: Astronomy for Binoculars and Richest-Field Telescopes , publisher=

Springer Science & Business Media Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing. Originally founded in 1842 i ...

, year=2012 , isbn=978-3709106266 , url=https://books.google.com/books?id=3vELBwAAQBAJ&pg=PA61 , access-date=2015-11-10 , postscript=. {{citation , display-authors=1 , last1=Piskunov , first1=A. E. , last2=Kharchenko , first2=N. V. , last3=Röser , first3=S. , last4=Schilbach , first4=E. , last5=Scholz , first5=R.-D. , title=Revisiting the population of Galactic open clusters , journal=Astronomy and Astrophysics , volume=445 , issue=2 , pages=545–565 , date=January 2006 , doi=10.1051/0004-6361:20053764 , bibcode=2006A&A...445..545P , postscript=. , arxiv = astro-ph/0508575 , s2cid=18970078 {{cite simbad , title=NAME del Lyr Cluster , accessdate=2015-11-10 , postscript=. Lyra (constellation) Open clusters

See also

References