NGC 6811

Last updated
NGC 6811
NGC 6811.png
Observation data (2000.0 epoch)
Right ascension 19h 37m 17s [1]
Declination +46° 23′ 18″
Distance 3600 ly [2] (1107 pc [2] )
Apparent magnitude  (V)6.8
Apparent dimensions (V)13'
Physical characteristics
Estimated age1.00±0.17 Gyr
Other designations Cr 402
Associations
Constellation Cygnus
See also: Open cluster, List of open clusters

NGC 6811 is an open cluster in the constellation of Cygnus, [3] near the constellation of Lyra. [4] It has an angular size half that of the full Moon and includes about 1000 stars [5] of roughly similar magnitude. [3] [6] It has also been called "The Hole in the Cluster" because of its dark center. [6] [7]

Contents

Features

NGC 6811 lies far away from the galactic plane, a feature it shares with many other old open clusters. [6] It is 1107 ± 90 parsecs (about 3,285 light years) distant [2] [8] and approximately 4-6 parsecs (14–20 light years) in diameter, [6] [9] with a total luminosity of 2100 suns. [9] Approximately 1.00 ± 0.17 billion years old, the cluster probably contained some 6000 stars at birth, [4] but gravitational interactions and stellar evolution have since reduced the number substantially. A recent study reported 377 confirmed member stars, with spectral types ranging from mid-F to early K, and surface temperatures relatively similar to the Sun's. [4] The same study argued that the original cluster population likely included 8 O-type stars and 125 B-type stars, but all have evolved off the main sequence and are undetectable. [4] Sixteen stars have been observed to vary in brightness, twelve of which are Delta Scuti variables. [10] The cluster's Trumpler classification is III 1r—it is "a rich cluster with equally bright stars with no noticeable central concentration". [6] The stars do, however, have an unusual (if not concentrated) distribution, with an apparent stellar corona surrounding the core, leaving the impression of a hole. [6]

Observation

NGC 6811 was first observed by John Herschel in 1829 and was added to his General Catalogue of Nebulae and Clusters in 1864. [11] The cluster has been the subject of study by the Kepler mission, with the aim of characterizing its stars' rotation rate, age, and distance to help the hunt for exoplanets. [4]

NGC 6811 is best observed from Earth in the Northern Hemisphere in summer. In these conditions it lies close to the zenith during the night, northeast of Delta Cygni. [3] It is considered an aesthetically pleasant object for amateur astronomers, even if the brightest members are just 10th magnitude objects. It appears as a hazy patch in 10x binoculars, but it is best seen at around 70x with a moderate-aperture telescope. [9] It has been described by amateur astronomers as a "smoke ring of stars" or "a jeweled mask a woman might wear at a masquerade ball". [6]

Planets

Two planets (Kepler 66b and Kepler 67b), orbiting Sun-like stars in the NGC 6811 cluster, have been discovered by the Kepler mission using the transit method. [2] Both planets are smaller than Neptune and are both the first sub-Jupiter planets and the first transiting planets discovered orbiting stars within an open cluster. [2] Given that the age and distance of the cluster have been accurately measured, the two planets are among the few of which age and distance are accurately known. [12] This finding suggests that the frequency of planets in clusters is similar to that in stars not belonging to clusters or associations [2] [12] and that planets can form and survive in environments more crowded and violent than the one of our own Sun. [5]

Map showing location of NGC 6811 NGC 6811 map.png
Map showing location of NGC 6811

See also

Related Research Articles

<span class="mw-page-title-main">Cygnus (constellation)</span> Constellation in the northern celestial hemisphere

Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross. Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.

<span class="mw-page-title-main">Fornax</span> Constellation in the southern celestial hemisphere

Fornax is a constellation in the southern celestial hemisphere, partly ringed by the celestial river Eridanus. Its name is Latin for furnace. It was named by French astronomer Nicolas Louis de Lacaille in 1756. Fornax is one of the 88 modern constellations.

<span class="mw-page-title-main">Lyra</span> Constellation in the northern celestial hemisphere

Lyra 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 maps as a vulture or an eagle carrying a lyre, and hence is sometimes referred to as Vultur Cadens or Aquila Cadens, respectively. Beginning at the north, Lyra is bordered by Draco, Hercules, Vulpecula, and Cygnus. Lyra is nearly overhead in temperate northern latitudes shortly after midnight at the start of summer. From the equator to about the 40th parallel south it is visible low in the northern sky during the same months.

<span class="mw-page-title-main">Ophiuchus</span> Zodiac constellation straddling the celestial equator

Ophiuchus is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek ὀφιοῦχος (ophioûkhos), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. An old alternative name for the constellation was Serpentarius.

<span class="mw-page-title-main">Lynx (constellation)</span> Constellation in the northern celestial hemisphere

Lynx is a constellation named after the animal, usually observed in the Northern Celestial Hemisphere. The constellation was introduced in the late 17th century by Johannes Hevelius. It is a faint constellation, with its brightest stars forming a zigzag line. The orange giant Alpha Lyncis is the brightest star in the constellation, and the semiregular variable star Y Lyncis is a target for amateur astronomers. Six star systems have been found to contain planets. Those of 6 Lyncis and HD 75898 were discovered by the Doppler method; those of XO-2, XO-4, XO-5 and WASP-13 were observed as they passed in front of the host star.

<span class="mw-page-title-main">Perseus (constellation)</span> Constellation in the northern celestial hemisphere

Perseus is a constellation in the northern sky, named after the Greek mythological hero Perseus. It is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy, and among the 88 modern constellations defined by the International Astronomical Union (IAU). It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda to the west and Cassiopeia to the north. Perseus is also bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis to the north, and Triangulum to the west. Some star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose asterism was named together as Perseus et Caput Medusae; however, this never came into popular usage.

<span class="mw-page-title-main">Vulpecula</span> Constellation in the northern celestial hemisphere

Vulpecula is a faint constellation in the northern sky. Its name is Latin for "little fox", although it is commonly known simply as the fox. It was identified in the seventeenth century, and is located in the middle of the Summer Triangle.

<span class="mw-page-title-main">Beehive Cluster</span> Open cluster in the constellation Cancer

The Beehive Cluster, is an open cluster in the constellation Cancer. One of the nearest open clusters to Earth, it contains a larger population of stars than other nearby bright open clusters holding around 1,000 stars. Under dark skies, the Beehive Cluster looks like a small nebulous object to the naked eye, and has been known since ancient times. Classical astronomer Ptolemy described it as a "nebulous mass in the breast of Cancer". It was among the first objects that Galileo studied with his telescope.

<span class="mw-page-title-main">NGC 752</span> Open cluster in the constellation Andromeda

NGC 752 is an open cluster in the constellation Andromeda. The cluster was discovered by Caroline Herschel in 1783 and cataloged by her brother William Herschel in 1786, although an object that may have been NGC 752 was described by Giovanni Batista Hodierna before 1654.

<span class="mw-page-title-main">Merope (star)</span> B-type subgiant star in the constellation Taurus

Merope, designated 23 Tauri, is a star in the constellation of Taurus and a member of the Pleiades star cluster. It is approximately 440 light-years (135 pc) away.

<span class="mw-page-title-main">NGC 663</span> Open star cluster in the constellation Cassiopeia

NGC 663 is a young open cluster in the constellation of Cassiopeia. It has an estimated 400 stars and spans about a quarter of a degree across the sky. It can reportedly be detected with the unaided eye, although a telescope is recommended for best viewing. The brightest members of the cluster can be viewed with binoculars. Although the listed visual magnitude is 7.1, several observers have reported higher estimates.

<span class="mw-page-title-main">Xi Cygni</span> Star in the constellation Cygnus

ξ Cygni is a spectroscopic binary star in the constellation Cygnus. Its apparent magnitude is 3.73 and it is located around 360 parsecs (1,200 ly) away.

Kepler-66 is a star with slightly more mass than the Sun in the NGC 6811 open cluster in the Cygnus constellation. It has one confirmed planet, slightly smaller than Neptune, announced in 2013.

Kepler-67 is a star in the open cluster NGC 6811 in the constellation Cygnus. It has slightly less mass than the Sun and has one confirmed planet, slightly smaller than Neptune, announced in 2013.

<span class="mw-page-title-main">NGC 6939</span> Open cluster in the constellation Cepheus

NGC 6939 is an open cluster in the constellation Cepheus. It was discovered by William Herschel in 1798. The cluster lies 2/3° northwest from the spiral galaxy NGC 6946. The cluster lies approximately 4,000 light years away and it is over a billion years old.

<span class="mw-page-title-main">NGC 2539</span> Open cluster in the constellation Puppis

NGC 2539 is an open cluster in the constellation Puppis, located at the north edge of the constellation. It was discovered by William Herschel on January 31, 1785. It is a moderately rich cluster and with little central concentration, with Trumpler class II1m.

<span class="mw-page-title-main">NGC 7160</span> Open cluster in the constellation Cepheus

NGC 7160 is an open cluster in the constellation Cepheus. It was discovered by William Herschel on November 9, 1789. The cluster was also observed by John Herschel on October 7, 1829. It is a poor cluster and with little central concentration, with Trumpler class II3p. It is part of the stellar association Cepheus OB2, located one degree south-southwest of VV Cephei.

<span class="mw-page-title-main">NGC 6910</span> Open cluster in the constellation Cygnus

NGC 6910 is an open cluster in the constellation Cygnus. It was discovered by William Herschel on October 17, 1786. The cluster was also observed by John Herschel on September 18, 1828. It is a poor cluster with prominent central concentration and Trumpler class I2p. NGC 6910 is the core cluster of the stellar association Cygnus OB9.

Planet-hosting stars are stars which host planets, therefore forming planetary systems.

WASP-84, also known as BD+02 2056, is a G-type main-sequence star 327 light-years away in the constellation Hydra. Its surface temperature is 5350±31 K, and is slightly enriched in heavy elements compared to the Sun, with a metallicity Fe/H index of 0.05±0.02. It is rich in carbon and depleted of oxygen. WASP-84's age is probably older than the Sun at 8.5+4.1
−5.5 billion years. The star appears to have an anomalously small radius, which can be explained by the unusually high helium fraction or by it being very young.

References

  1. ↑ "NGC 6811". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 11 May 2013.
  2. 1 2 3 4 5 6 Meibom, S. R.; Torres, G.; Fressin, F.; Latham, D. W.; Rowe, J. F.; Ciardi, D. R.; Bryson, S. T.; Rogers, L. A.; Henze, C. E.; Janes, K.; Barnes, S. A.; Marcy, G. W.; Isaacson, H.; Fischer, D. A.; Howell, S. B.; Horch, E. P.; Jenkins, J. M.; Schuler, S. C.; Crepp, J. (2013). "The same frequency of planets inside and outside open clusters of stars". Nature. 499 (7456): 55–58. arXiv: 1307.5842 . Bibcode:2013Natur.499...55M. doi:10.1038/nature12279. PMID   23803764. S2CID   4356893.
  3. 1 2 3 Ayiomamitis, Anthony. "NGC 6811". Astronomy Magazine. Kalmach Publishing Co. Retrieved 9 July 2013.
  4. 1 2 3 4 5 Meibom, S. R.; Barnes, S. A.; Latham, D. W.; Batalha, N.; Borucki, W. J.; Koch, D. G.; Basri, Gibor; Walkowicz, L. M.; Janes, K. A.; Jenkins, J.; Van Cleve, J.; Haas, M. R.; Bryson, S. T.; Dupree, A. K.; Furesz, G.; Szentgyorgyi, A. H.; Buchhave, L. A.; Clarke, B. D.; Twicken, J. D.; Quintana, E. V. (2011). "The Kepler Cluster Study: Stellar Rotation in Ngc 6811". The Astrophysical Journal. 733 (1): L9. arXiv: 1104.2912 . Bibcode:2011ApJ...733L...9M. doi:10.1088/2041-8205/733/1/L9. S2CID   118585956.
  5. 1 2 Balouchi, Shari. "Crowded Clusters Can Host Planets, Too". Sky and Telescope. Archived from the original on 10 July 2013. Retrieved 9 July 2013.
  6. 1 2 3 4 5 6 7 Stephen James O'Meara (30 June 2011). Deep-Sky Companions: The Secret Deep. Cambridge University Press. pp. 389–. ISBN   978-1-139-50007-4 . Retrieved 9 July 2013.
  7. ↑ L. Phil Simpson (2012). Guidebook to the Constellations. Springer. pp. 505–. ISBN   978-1-4419-6941-5 . Retrieved 9 July 2013.
  8. ↑ Janes, K.; Barnes, S. A.; Meibom, S. R.; Hoq, S. (2013). "Ngc 6811: An Intermediate-Age Cluster in the Kepler Field". The Astronomical Journal. 145 (1): 7. Bibcode:2013AJ....145....7J. doi: 10.1088/0004-6256/145/1/7 .
  9. 1 2 3 Craig Crossen; Gerald Rhemann (27 January 2004). Sky Vistas: Astronomy for Binoculars and Richest-Field Telescopes. Springer. pp.  67–. ISBN   978-3-211-00851-5 . Retrieved 9 July 2013.
  10. ↑ Luo, Y. P.; Zhang, X. B.; Luo, C. Q.; Deng, L. C.; Luo, Z. Q. (2009). "Variable stars in the open cluster NGC 6811". New Astronomy. 14 (6): 584. arXiv: 1410.2178 . Bibcode:2009NewA...14..584L. doi:10.1016/j.newast.2009.02.005.
  11. ↑ "The NGC/IC Project". Results for NGC 6811. Archived from the original on 28 May 2009. Retrieved 11 May 2013.
  12. 1 2 "First Transiting Planets in a Star Cluster Discovered". Harvard-Smithsonian Center for Astrophysics. 2013-06-26. Retrieved 9 July 2013.
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