NGC 6791

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NGC 6791
NGC 6791 cluster.jpg
Detail from the Kepler image showing NGC 6791. Celestial north is to the left. a
Observation data (J2000 epoch)
Right ascension 19h 20m 53s [1]
Declination +37° 46.3 [1]
Distance ~13,300 ly (4078 pc)
Apparent magnitude (V)+9.5 [1]
Apparent dimensions (V)16' [2]
Physical characteristics
One of the oldest known open clusters
Other designationsC 1919+377, Cl Berkeley 46, OCl 142.0, [1] GC 4492 [2]
Associations
Constellation Lyra
See also: Open cluster, List of open clusters

NGC 6791 is an open star cluster in the Lyra constellation. [1] It was discovered by Friedrich August Theodor Winnecke in 1853. At roughly 8 billion years old, and with an iron to hydrogen abundance ratio that is more than twice that of the Sun, it is one of the oldest and most metal-rich clusters in the Milky Way. This is contrary to the typical rule-of-thumb where older means more metal-poor. Compounded with the fact that it has an unusually high population of stars, NGC 6791 is among the most studied clusters in the sky. [3] [4]

Contents

Age studies

Among the dimmest stars in the cluster are groups of white dwarfs that are 6 billion years old and another group that appear to be 4 billion years old. The ages are out of sync with those of the cluster's normal stars, which are 8 billion years old. This seeming contradiction in age for this cluster has been studied and a solution proposed with age of about 8 billion years. [5] [6] [7]

The Kepler Mission

An image from Kepler with NGC 6791 and another point of interest outlined. Celestial north is to the left. 329161main fullFFIHot300.png
An image from Kepler with NGC 6791 and another point of interest outlined. Celestial north is to the left.

In March 2009 NASA launched the Kepler Mission spacecraft. This spacecraft was a dedicated mission to discover extrasolar planets by the transit method from solar orbit. In April 2009 the project released the first light images from the spacecraft and NGC 6791 was one of two objects highlighted. [8]

The planet hosting star Kepler-19, discovered from Kepler data, is located approximately 5 arcminutes northwest of NGC 6791. [9] The star has a differing proper motion to the cluster and is also much closer, so it is unrelated.

Map showing location of NGC 6791 (Roberto Mura) NGC 6791 map.png
Map showing location of NGC 6791 (Roberto Mura)

Notes

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">Globular cluster</span> Spherical collection of stars

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 stars. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".

<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">Kepler space telescope</span> NASA satellite for exoplanetology (2009–2018)

The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orbit. The principal investigator was William J. Borucki. After nine and a half years of operation, the telescope's reaction control system fuel was depleted, and NASA announced its retirement on October 30, 2018.

<span class="mw-page-title-main">NGC 404</span> Lenticular galaxy in the constellation Andromeda

NGC 404 is a field galaxy located about 10 million light years away in the constellation Andromeda. It was discovered by William Herschel in 1784, and is visible through small telescopes. NGC 404 lies just beyond the Local Group and does not appear gravitationally bound to it. It is located within 7 arc-minutes of second magnitude star Mirach, making it a difficult target to observe or photograph and granting it the nickname "Mirach's Ghost".

<span class="mw-page-title-main">NGC 6397</span> Globular cluster of stars in the Milky Way

NGC 6397 is a globular cluster in the constellation Ara. It is located about 7,800 light-years from Earth, making it one of the two nearest globular clusters to Earth. The cluster contains around 400,000 stars, and can be seen with the naked eye under good observing conditions.

<span class="mw-page-title-main">Messier 2</span> Globular cluster in the constellation Aquarius

Messier 2 or M2 is a globular cluster in the constellation Aquarius, five degrees north of the star Beta Aquarii. It was discovered by Jean-Dominique Maraldi in 1746, and is one of the largest known globular clusters.

<span class="mw-page-title-main">Messier 49</span> Elliptical galaxy in the constellation Virgo

Messier 49 is a giant elliptical galaxy about 56 million light-years away in the equatorial constellation of Virgo. This galaxy was discovered by astronomer Charles Messier in 1777.

<span class="mw-page-title-main">Messier 67</span> Old open cluster in the constellation Cancer

Messier 67 and sometimes called the King Cobra cluster or the Golden Eye cluster is an open cluster in the southern, equatorial half of Cancer. It was discovered by Johann Gottfried Koehler in 1779. Estimates of its age range between 3.2 and 5 billion years. Distance estimates are likewise varied, but typically are 800–900 parsecs (2,600–2,900 ly). Estimates of 855, 840, and 815 pc were established via binary star modelling and infrared color-magnitude diagram fitting.

<span class="mw-page-title-main">47 Tucanae</span> Globular cluster in the constellation Tucana

47 Tucanae or 47 Tuc is a globular cluster located in the constellation Tucana. It is about 4.45 ± 0.01 kpc (15,000 ± 33 ly) away from Earth, and 120 light years in diameter. 47 Tuc can be seen with the naked eye, with an apparent magnitude of 4.1. It appears about 44 arcminutes across including its far outreaches. Due to its far southern location, 18° from the south celestial pole, it was not catalogued by European astronomers until the 1750s, when the cluster was first identified by Nicolas-Louis de Lacaille from South Africa.

The Canis Major Overdensity or Canis Major Dwarf Galaxy is a disputed dwarf irregular galaxy in the Local Group, located in the same part of the sky as the constellation Canis Major.

<span class="mw-page-title-main">NGC 1569</span> Dwarf irregular galaxy in the constellation Camelopardalis

NGC 1569 is a dwarf irregular galaxy in Camelopardalis. The galaxy is relatively nearby and consequently, the Hubble Space Telescope can easily resolve the stars within the galaxy. The distance to the galaxy was previously believed to be only 2.4 Mpc. However, in 2008 scientists studying images from Hubble calculated the galaxy's distance at nearly 11 million light-years away, about 4 million light-years farther than previous thought, meaning it is a member of the IC 342 group of galaxies.

<span class="mw-page-title-main">NGC 1705</span> Peculiar lenticular galaxy in the constellation Pictor

NGC 1705 is a peculiar lenticular galaxy and a blue compact dwarf galaxy (BCD) in the southern constellation of Pictor, positioned less than a degree to the east of Iota Pictoris, and is undergoing a starburst. With an apparent visual magnitude of 12.6 it requires a telescope to observe. It is estimated to be approximately 17 million light-years from the Earth, and is a member of the Dorado Group.

<span class="mw-page-title-main">Tucana Dwarf</span> Dwarf galaxy in the constellation Tucana

The Tucana Dwarf Galaxy is a dwarf galaxy in the constellation Tucana. It was discovered in 1990 by R.J. Lavery of Mount Stromlo Observatory. It is composed of very old stars and is very isolated from other galaxies. Its location on the opposite side of the Milky Way from other Local Group galaxies makes it an important object for study.

<span class="mw-page-title-main">NGC 2547</span> Open cluster in the constellation Vela

NGC 2547 is a southern open cluster in Vela, discovered by Nicolas Louis de Lacaille in 1751 from South Africa. The star cluster is young with an age of 20-30 million years.

<span class="mw-page-title-main">NGC 4449</span> Galaxy in the constellation Canes Venatici

NGC 4449, also known as Caldwell 21, is an irregular Magellanic type galaxy in the constellation Canes Venatici, being located about 13 million light-years away. It is part of the M94 Group or Canes Venatici I Group that is relatively close to the Local Group hosting our Milky Way galaxy.

<span class="mw-page-title-main">NGC 2808</span> Globular cluster in the constellation Carina

NGC 2808 is a globular cluster in the constellation Carina. The cluster belongs to the Milky Way, and is one of our home galaxy's most massive clusters, containing more than a million stars. It is estimated to be 12.5-billion years old.

<span class="mw-page-title-main">GSC 03549-02811</span> Main sequence - star in the constellation Draco

GSC 03549-02811, also known as Kepler-1) is a yellow main-sequence star similar to the Sun. This star is located approximately 704 light-years away in the constellation of Draco. The apparent magnitude of this star is 11.41, which means it is not visible to the naked eye but can be seen with a medium-sized amateur telescope on a clear dark night. The age of this star is about 5 billion years.

Kepler-444 is a triple star system, estimated to be 11.2 billion years old, approximately 119 light-years (36 pc) away from Earth in the constellation Lyra. On 27 January 2015, the Kepler spacecraft is reported to have confirmed the detection of five sub-Earth-sized rocky exoplanets orbiting the main star. The star is a K-type main sequence star. All of the planets are far too close to their star to harbour life forms.

References

  1. 1 2 3 4 5 "NGC 6791". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2009-05-10.
  2. 1 2 NGC online. "NGC 6791". Archived from the original on 2007-08-19. Retrieved 2009-05-10.
  3. Chaboyer; Green, Elizabeth M.; Liebert, James (March 1999). "The Age, Extinction, and Distance of the Old, Metal-rich Open Cluster NGC 6791" (PDF). The Astronomical Journal . 117 (3): 1360–1374. arXiv: astro-ph/9812097 . Bibcode:1999AJ....117.1360C. doi:10.1086/300794. S2CID   16633286.
  4. Kaluzny; Udalski, A. (1992). "Photometric Study of the Old Open Cluster NGC 6791" (PDF). Acta Astronomica . 42 (1): 29–47. Bibcode:1992AcA....42...29K.
  5. Bedin; King, Ivan R.; Anderson, Jay; Piotto, Giampaolo; et al. (May 10, 2008). "Reaching the End of the White Dwarf Cooling Sequence in NGC 67911" (PDF). The Astrophysical Journal. 678 (2): 1279–1291. arXiv: 0801.1346 . Bibcode:2008ApJ...678.1279B. doi:10.1086/529370. S2CID   18969486. Archived from the original (PDF) on March 31, 2017. Retrieved May 10, 2009.
  6. Bedin; Salaris, M.; Piotto, G.; Cassisi, S.; et al. (May 20, 2008). "The Puzzling White Dwarf Cooling Sequence in NGC 6791: A Simple Solution" (PDF). The Astrophysical Journal Letters. 679 (1): L29–L32. arXiv: 0804.1792 . Bibcode:2008ApJ...679L..29B. doi:10.1086/589151. S2CID   17920160. Archived from the original (PDF) on March 31, 2017. Retrieved May 10, 2009.
  7. Grundahl; Clausen, J. V.; Hardis, S.; Frandsen, S. (2008). "A new standard: age and distance for the open cluster. NGC6791 from the eclipsing binary member V20". Astronomy & Astrophysics . 492 (1): 171–184. arXiv: 0810.2407 . Bibcode:2008A&A...492..171G. doi:10.1051/0004-6361:200810749. S2CID   18569623.
  8. "Kepler Eyes Cluster and Known Planet". NASA. 2009-04-16. Retrieved 2009-05-09.
  9. "SIMBAD clickable map".