The Delta Lyrae cluster or Stephenson 1 is a sparse

open cluster An open cluster is a type of star cluster made of tens 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 (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

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 first constellati ...

Lyra , from ; pronounced: ) 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 often represented on star ...

. Centered on the bright star Delta² Lyrae for which it is named but not a member like Delta¹ Lyrae is with 70% certainty. 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 a professor at Case Western Reserve University. Biography He was born on a ranch in Little Rock, Arkansas, the only son of Chauncey Elvira Stephe ...

, 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 Mountain, California, an unincorporated community ** Palomar College in San Marcos, California *** Palomar College Transit Ce ...

and Mount Wilson observatories led American astronomer Olin J. Eggen 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 Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light ca ...

of 3.8 and spans an

angular diameter The angular diameter, angular size, apparent diameter, or apparent size is an angular separation (in units of angle) describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the ''visual an ...

of 20

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

s. The

tidal radius A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards its center. It can contain anywhere from tens of thousands to many millions of member stars, all orbiting ...

of the cluster is and it has an estimated combined mass of 589 times the

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

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

Gould Belt The Gould Belt is a local ring of stars in the Milky Way, tilted away from the galactic plane by about 16–20 degrees, first reported by John Herschel and Benjamin Gould in the 19th century. It contains many O- and B-type stars, and many o ...

. 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 A binary star or binary star system is a system of two stars that are 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 as separate stars us ...

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) a ...

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 ...

to the Earth. An

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

has been found orbiting the star Kepler-1627 in this cluster.

References

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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 in astronomy, astrophysics and related fields. It publishes original research in two formats: papers (of any length) and letters (limited to ...

, 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 , doi-access = free , 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 in ...

, 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=2023-05-25 , postscript=. {{cite journal , last1=Bouma , first1=L. G. , last2=Curtis , first2=J. L. , display-authors=etal , date=March 2022 , title=A 38 Million Year Old Neptune-sized Planet in the Kepler Field , journal=

The Astronomical Journal ''The Astronomical Journal'' (often abbreviated ''AJ'' in scientific papers and references) is a peer-reviewed monthly scientific journal owned by the American Astronomical Society (AAS) and currently published by IOP Publishing. It is one of the p ...

, volume=163 , issue=3 , pages=121 , doi=10.3847/1538-3881/ac4966 , arxiv=2112.14776 , bibcode=2022AJ....163..121B , doi-access=free Lyra Open clusters

See also

References