Table of Contents Categories
  • Carina–Sagittarius Arm
  • Scutum (constellation)
  • Messier objects
  • NGC objects
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    Messier 26

    Topic: Astronomy

     From Handwiki - Reading time: 3 min
    Short description: Open cluster in the constellation Scutum
    Messier 26
    File:280px
    Open cluster Messier 26
    Credit: Hillary Mathis, Vanessa Harvey, REU program/NOIRLab/NSF/AURA
    Observation data (J2000.0 epoch)
    ConstellationScutum
    Right ascension 18h 45m 18.0s[1]
    Declination−09° 23′ 00″[1]
    Distance5,160 ly (1,582 pc)[2]
    Apparent magnitude (V)8.0[3]
    Apparent dimensions (V)14′[3]
    Physical characteristics
    Radius11 ly[4]
    Estimated age85.3[1] million years
    Other designationsMessier 26, NGC 6694,[5] Cr 389, C 1842-094
    See also: Open cluster, List of open clusters

    Messier 26, also known as NGC 6694, is an open cluster of stars in the southern constellation of Scutum. It was discovered by Charles Messier in 1764.[lower-alpha 1] This 8th magnitude cluster is a challenge to find in ideal skies with typical binoculars, where it can be, with any modern minimum 3-inch (76 mm) aperture device. It is south-southwest of the open cluster Messier 11 and is 14′ across.[3] About 25 stars are visible in a telescope with a 150–200 mm (6–8 in) aperture.[6]

    M26 spans a linear size of 22[4] light years across with a tidal radius of 25 light-years,[7] and is at a distance of 5,160[2] light years from the Earth. The brightest star is of magnitude 11[6] and the age of this cluster has been calculated to be 85.3[1] million years. It includes one known spectroscopic binary system.[8]

    An interesting feature of M26 is a region of low star density near the nucleus. A hypothesis was that it was caused by an obscuring cloud of interstellar matter between us and the cluster, but a paper by James Cuffey suggested that this is not possible and that it really is a "shell of low stellar space density".[9] In 2015, Michael Merrifield of the University of Nottingham said that there is, as yet, no clear explanation for the phenomenon.[10]

    Gallery

    • Map showing the location of M26 (Roberto Mura)

    See also

    Footnotes and references

    Footnotes

    1. ↑ On June 20

    References

    1. ↑ 1.0 1.1 1.2 1.3 Wu, Zhen-Yu et al. (November 2009), "The orbits of open clusters in the Galaxy", Monthly Notices of the Royal Astronomical Society 399 (4): 2146–2164, doi:10.1111/j.1365-2966.2009.15416.x, Bibcode: 2009MNRAS.399.2146W. 
    2. ↑ 2.0 2.1 Kharchenko, N. V. et al. (2005), "Astrophysical parameters of Galactic open clusters", Astronomy and Astrophysics 438 (3): 1163–1173, doi:10.1051/0004-6361:20042523, Bibcode: 2005A&A...438.1163K. 
    3. ↑ 3.0 3.1 3.2 Thompson, Robert; Thompson, Barbara (2007), Illustrated Guide to Astronomical Wonders: From Novice to Master Observer, DIY science, O'Reilly Media, Inc., p. 431, ISBN 978-0596526856, https://books.google.com/books?id=ymt9nj_uPhwC&pg=PA431 
    4. ↑ 4.0 4.1 Kharchenko, N. V. et al. (March 2009), "Shape parameters of Galactic open clusters", Astronomy and Astrophysics 495 (3): 807–818, doi:10.1051/0004-6361/200810407, Bibcode: 2009A&A...495..807K. 
    5. ↑ "M 26". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=M+26. 
    6. ↑ 6.0 6.1 Burnham, Robert (1978), Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System, Dover books on astronomy, 3, Courier Corporation, p. 1756, ISBN 978-0486236735, https://books.google.com/books?id=tBQoCSRdLAAC&pg=PA1756 
    7. ↑ Piskunov, A. E. et al. (January 2008), "Tidal radii and masses of open clusters", Astronomy and Astrophysics 477 (1): 165–172, doi:10.1051/0004-6361:20078525, Bibcode: 2008A&A...477..165P. 
    8. ↑ Mermilliod, J. -C. et al. (October 2007), "Red giants in open clusters. XIII. Orbital elements of 156 spectroscopic binaries", Astronomy and Astrophysics 473 (3): 829–845, doi:10.1051/0004-6361:20078007, Bibcode: 2007A&A...473..829M. 
    9. ↑ Cuffey, James (1940). "The Galactic Clusters NGC 6649 and NGC 6694". Astrophysical Journal 92: 303. doi:10.1086/144220. Bibcode: 1940ApJ....92..303C. 
    10. ↑ Merrifield, Michael (Oct 2, 2015). "M26 - Open Cluster". University of Nottingham/University of Sheffield. http://www.deepskyvideos.com/videos/messier/M26.html. 

    External links

    Coordinates: Sky map 18h 45.2m 00s, −09° 24′ 00″



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