NGC 2420

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NGC 2420
Solar composition star cluster - Noao0203a.jpg
NGC 2420 by the refurbished WIYN 0.9-meter telescope at Kitt Peak National Observatory
Observation data (J2000 epoch)
Right ascension 07h 38m 25s [1]
Declination +21° 34′ 30″ [1]
Distance 10,060 ly [2] (3,085 pc [2] )
Apparent magnitude  (V)8.3 [1]
Apparent dimensions (V)6.4'
Physical characteristics
Estimated age2 billion years
Other designations Melotte 69, Collinder 154
Associations
Constellation Gemini
See also: Open cluster, List of open clusters

NGC 2420 is an open cluster in the constellation Gemini. It was discovered by William Herschel in 1783. The cluster is about two billion years old and it is located 10,000 light years away.

Contents

Observation

The location of NGC 2420 NGC 2420 map.png
The location of NGC 2420

NGC 2420 lies about 6,5 degrees south-southeast of the star Pollux and a bit over two degrees east-northeast of the Eskimo Nebula. Through a small telescope at low magnification it appears as a uniform ghostly light that gets brighter to the centre, similar to a tail-less comet and at x33 magnification some individual stars can be glimpsed with averted vision. At higher magnification the cluster is resolved into a rich field of individual stars. It is included in the Herschel 400 Catalogue. [3] [4]

Characteristics

The cluster is located at a greater distance from the galactic centre than the Sun, lying in the direction of the galactic anti-centre, [5] and lies 19° above the galactic plane, which corresponds to a distance of 3,000 light years. It has a Trumpler classification of I1r, [4] indicating a rich detached cluster with a central concentration made out of stars of similar apparent magnitude. Photographic photometry down to magnitude 19 indicates that the cluster has over 500 members, with the brightest being of 11th magnitude. [6] The total number of members is estimated to be around 1,000 within a diameter of 30 light years. [7]

It is estimated that 41% of the stars of the cluster are binaries. [8] The cluster has been found to contain two binary systems made out of two blue stragglers, while a third binary system is made out of a blue straggler and an extremely low mass white dwarf. These binary stars shine bright in far ultraviolet. [9] Using data from the Hubble Space Telescope, von Hippel and Gilmore detected eight white dwarf candidates and estimated a cooling age of about 2 billion years. [10]

The metallicity of the cluster has been a subject of many studies and has been found to be a bit sub-solar, with a metallicity of -0.26 according to WEBDA. [2] The cluster was found to be a bit metal poor, with a [Fe/H] of -0.7 to -0.6 from spectrographic studies performed in the 1980s [11] [12] [13] while subsequent CCD photometry indicates of a higher metallicity of about -0.30. [14] Pancino et al. indicated a [Fe/H]= -0.05 ± 0.03 according to Pancino et al., which is close to the trend of metallicity descreasing with increasing distance from the galactic centre. [15] The red giants of the cluster have a mean metallicity of −0.16 ± 0.04. [5] Based on spectrographic data of the Gaia-ESO survey, the stars around the turnoff point have sub-solar metallicities but they increase for stars of smaller mass. [16]

The stars of the cluster have homogenous CN and CH molecular band strengths. [17] Similar low dispersion was observed in other elements. [5]

See also

Related Research Articles

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<span class="mw-page-title-main">NGC 5822</span> Open cluster in the constellation Lupus

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<span class="mw-page-title-main">NGC 5986</span> Globular cluster in the constellation Lupus

NGC 5986 is a globular cluster of stars in the southern constellation of Lupus, located at a distance of approximately 34 kilolight-years from the Sun. It was discovered by Scottish astronomer James Dunlop on May 10, 1826. John L. E. Dreyer described it as, "a remarkable object, a globular cluster, very bright, large, round, very gradually brighter middle, stars of 13th to 15th magnitude". Its prograde–retrograde orbit through the Milky Way galaxy is considered irregular and highly eccentric. It has a mean heliocentric radial velocity of +100 km/s. The galacto-centric distance is 17 kly (5.2 kpc), which puts it in the galaxy's inner halo.

<span class="mw-page-title-main">NGC 6934</span> Globular cluster in the constellation Delphinus

NGC 6934 is a globular cluster of stars in the northern constellation of Delphinus, about 52 kilolight-years distant from the Sun. It was discovered by the German-born astronomer William Herschel on 24 September 1785. The cluster is following a highly eccentric orbit through the Milky Way along an orbital plane that is inclined by 73° to the galactic plane. It may share a common dynamic origin with NGC 5466. As of 2018, it has been poorly studied.

<span class="mw-page-title-main">NGC 6193</span> Open star cluster in the constellation Ara

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<span class="mw-page-title-main">NGC 2506</span> Open cluster in the constellation Monoceros

NGC 2506 is a mildly-elongated open cluster of stars in the equatorial constellation of Monoceros, located at a distance of 12.7 kly from the Sun near the Galactic anti-center. It was discovered by William Herschel in 1791. The cluster lies around 10,000 ly from the Galactic Center and about 1,600 ly above the Galactic plane. It is of intermediate age, estimated at around two billion years. The cluster has an angular radius of 12′ and a core radius of 4.8′.

<span class="mw-page-title-main">NGC 4609</span> Open cluster in the constellation Crux

NGC 4609 is an open cluster of stars in the southern constellation of Crux. It was discovered on May 12, 1826 by the Scottish astronomer James Dunlop. The cluster has an apparent visual magnitude of 6.9 and spans an angular size of 6.5′. It is situated beyond the Coalsack Nebula at an estimated distance of 4,500 ly (1,379 pc) from the Sun.

<span class="mw-page-title-main">NGC 6388</span> Globular cluster in the constellation Scorpius

NGC 6388 is a globular cluster of stars located in the southern constellation of Scorpius. The cluster was discovered by Scottish astronomer James Dunlop on May 13, 1826 using a 20 cm (9 in) reflector telescope. It was later determined to be a globular cluster by English astronomer John Herschel, who was able to resolve it into individual stars. NGC 6388 is located at a distance of approximately 35,600 light-years (10.90 kpc) from the Sun. Due to its apparent visual magnitude of +6.8, binoculars or a small telescope are required to view it.

<span class="mw-page-title-main">NGC 121</span> Globular cluster in the constellation Tucana

NGC 121 is a globular cluster of stars in the southern constellation of Tucana. It is the oldest globular cluster in the Small Magellanic Cloud (SMC), which is a dwarf satellite galaxy of the Milky Way. This cluster was first discovered by English astronomer John Herschel on September 20, 1835. The compiler of the New General Catalogue, Danish astronomer John Louis Emil Dreyer, described this object as "pretty bright, pretty small, little extended, very gradually brighter middle". The cluster is located at a distance of around 200,000 light-years (60 kpc) from the Sun.

<span class="mw-page-title-main">NGC 6441</span> Globular cluster in Scorpius

NGC 6441, sometimes also known as the Silver Nugget Cluster, is a globular cluster in the southern constellation of Scorpius. It was discovered by the Scottish astronomer James Dunlop on May 13, 1826, who described it as "a small, well-defined rather bright nebula, about 20″ in diameter". The cluster is located 5 arc minutes east-northeast of the star G Scorpii, and is some 43,000 light-years from the Sun.

<span class="mw-page-title-main">NGC 5053</span> Globular cluster in the constellation Coma Berenices

NGC 5053 is the New General Catalogue designation for a globular cluster in the northern constellation of Coma Berenices. It was discovered by German-British astronomer William Herschel on March 14, 1784 and cataloged as VI-7. In his abbreviated notation, he described it as, "an extremely faint cluster of extremely small stars with resolvable nebula 8 or 10′ diameter, verified by a power of 240, beyond doubt". Danish-Irish astronomer John Louis Emil Dreyer reported in 1888 that the cluster appeared, "very faint, pretty large, irregular round shape, growing very gradually brighter at the middle".

<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 5617</span> Open cluster in the constellation Centaurus

NGC 5617 is an open cluster in the constellation Centaurus. NGC 5617 forms a binary open cluster with Trumpler 22. It lies one degree west-northwest of Alpha Centauri.

<span class="mw-page-title-main">NGC 4815</span> Open cluster in the constellation Musca

NGC 4815 is an open cluster in the constellation Musca. It was discovered by John Herschel in 1834. It is located approximately 10,000 light years away from Earth.

References

  1. 1 2 3 "NGC 2420". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2017-06-19.
  2. 1 2 3 "WEBDA: Open cluster page". webda.physics.muni.cz. Retrieved 16 June 2024.
  3. ↑ O'Meara, Stephen James (14 June 2007). Herschel 400 Observing Guide. Cambridge University Press. p. 75. ISBN   978-0-521-85893-9.
  4. 1 2 O'Meara, Stephen James (30 June 2011). Deep-Sky Companions: The Secret Deep. Cambridge University Press. pp. 166–168. ISBN   978-1-139-50007-4.
  5. 1 2 3 Souto, Diogo; Cunha, K.; Smith, V.; Prieto, C. Allende; Pinsonneault, M.; Zamora, O.; García-Hernández, D. A.; Mészáros, Sz.; Bovy, J.; Pérez, A. E. García; Anders, F.; Bizyaev, D.; Carrera, R.; Frinchaboy, P. M.; Holtzman, J.; Ivans, I.; Majewski, S. R.; Shetrone, M.; Sobeck, J.; Pan, K.; Tang, B.; Villanova, S.; Geisler, D. (10 October 2016). "Chemical Abundances in a Sample of Red Giants in the Open Cluster NGC 2420 from Apogee". The Astrophysical Journal. 830 (1): 35. arXiv: 1607.06102 . Bibcode:2016ApJ...830...35S. doi: 10.3847/0004-637X/830/1/35 .
  6. ↑ West, Frederick R. (September 1967). "Photographic Photometry of the Galactic Cluster NGC 2420". The Astrophysical Journal Supplement Series. 14: 384. Bibcode:1967ApJS...14..384W. doi:10.1086/190160.
  7. ↑ "Star Cluster with Surprising Similarities to Sun's Composition Offers Clues on Milky Way Evolution". www.noirlab.edu. Retrieved 16 June 2024.
  8. ↑ Thompson, Benjamin A.; Frinchaboy, Peter M.; Spoo, Taylor; Donor, John (1 April 2021). "The Binary INformation from Open Clusters Using SEDs (BINOCS) Project: Reliable Photometric Mass Determinations of Binary Star Systems in Clusters". The Astronomical Journal. 161 (4): 160. arXiv: 2101.07857 . Bibcode:2021AJ....161..160T. doi: 10.3847/1538-3881/abde4c .
  9. ↑ Yadav, R. K. S.; Dattatrey, Arvind K.; Rangwal, Geeta; Subramaniam, Annapurni; Bisht, D.; Sagar, Ram (1 February 2024). "UOCS. XIII. Study of the Far-ultraviolet Bright Stars in the Open Cluster NGC 2420 Using AstroSat". The Astrophysical Journal. 961 (2): 251. Bibcode:2024ApJ...961..251Y. doi: 10.3847/1538-4357/ad13e8 .
  10. ↑ von Hippel, Ted; Gilmore, Gerard (September 2000). "The White Dwarf Cooling Age of the Open Cluster NGC 2420". The Astronomical Journal. 120 (3): 1384–1395. arXiv: astro-ph/0006033 . Bibcode:2000AJ....120.1384V. doi:10.1086/301528.
  11. ↑ Cohen, J. G. (November 1980). "Abundances in globular cluster red giants. III - M71, M67, and NGC 2420". The Astrophysical Journal. 241: 981. Bibcode:1980ApJ...241..981C. doi:10.1086/158412.
  12. ↑ Smith, Verne V.; Suntzeff, Nicholas B. (February 1987). "Velocities and abundances of giant stars in the old open cluster NGC 2420". The Astronomical Journal. 93: 359. Bibcode:1987AJ.....93..359S. doi:10.1086/114320.
  13. ↑ Pilachowski, C. A.; Wallerstein, G.; Canterna, R. (January 1980). "The chemical compositions of stars in the globular cluster 47 Tucanae and the old disk cluster NGC 2420". The Astrophysical Journal. 235: L21. Bibcode:1980ApJ...235L..21P. doi:10.1086/183150.
  14. ↑ Anthony-Twarog, Barbara J.; Tanner, Delora; Cracraft, Misty; Twarog, Bruce A. (January 2006). "vby C a Hβ CCD Photometry of Clusters. VI. The Metal-deficient Open Cluster NGC 2420". The Astronomical Journal. 131 (1): 461–472. arXiv: astro-ph/0510047 . Bibcode:2006AJ....131..461A. doi:10.1086/498304.
  15. ↑ Pancino, E.; Carrera, R.; Rossetti, E.; Gallart, C. (February 2010). "Chemical abundance analysis of the open clusters Cr 110, NGC 2099 (M 37), NGC 2420, NGC 7789, and M 67 (NGC 2682)". Astronomy and Astrophysics. 511: A56. arXiv: 0910.0723 . Bibcode:2010A&A...511A..56P. doi:10.1051/0004-6361/200912965.
  16. ↑ Semenova, Ekaterina; Bergemann, Maria; Deal, Morgan; Serenelli, Aldo; Hansen, Camilla Juul; Gallagher, Andrew J.; Bayo, Amelia; Bensby, Thomas; Bragaglia, Angela; Carraro, Giovanni; Morbidelli, Lorenzo; Pancino, Elena; Smiljanic, Rodolfo (November 2020). "The Gaia -ESO survey: 3D NLTE abundances in the open cluster NGC 2420 suggest atomic diffusion and turbulent mixing are at the origin of chemical abundance variations". Astronomy & Astrophysics. 643: A164. arXiv: 2007.09153 . Bibcode:2020A&A...643A.164S. doi:10.1051/0004-6361/202038833.
  17. ↑ Carrera, R.; Martínez-Vázquez, C. E. (December 2013). "Searching for chemical inhomogeneities in open clusters: Analysis of the CN and CH molecular band strengths in NGC 2158, NGC 2420, NGC 2682, NGC 7789, and Berkeley 29⋆". Astronomy & Astrophysics. 560: A5. arXiv: 1308.4548 . Bibcode:2013A&A...560A...5C. doi:10.1051/0004-6361/201322048.
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