| 释义 |
- Gallery
- References
- External links
{{Infobox open cluster
| image =
| name = Messier 26
| epoch = J2000.0
| caption = 2MASS Atlas image
| class = II,2,r
| ra = {{RA|18|45|18.0}}[1]
| dec = {{Dec|−09|23|00}}[1]
| constellation = Scutum
| dist_ly = {{Convert|1582|kpc|kly|order=flip|abbr=on|lk=on}}[3]
| appmag_v = 8.0[4]
| size_v = {{Val|14|ul=arcminute}}[4]
| mass_msol =
| radius_ly = {{Convert|3.3|pc|ly|order=flip|abbr=on|disp=out}}[6]
| age = 85.3[1] million years
| notes =
| names = C 1842-094, Messier 26, NGC 6694
}}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 on June 20, 1764. This 8th magnitude cluster is a challenge to find with typical binoculars, but can be spotted with an 80mm aperture. It is positioned near the open cluster Messier 11 and is {{Val|14|ul=arcminute}} across.[4] About 25 stars are visible in a telescope with a {{Convert|6|-|8|in|mm|order=flip|abbr=on}} aperture.[10]M26 spans a linear size of 22[6] light years across with a tidal radius of {{Convert|7.6|pc|ly|order=flip|disp=out}},[12] and is at a distance of 5,160[3] light years from the Earth. The brightest star is of magnitude 11[10] and the age of this cluster has been calculated to be 85.3[1] million years. It includes one known spectroscopic binary system.[16] 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".[17] In 2015, Michael Merrifield of the University of Nottingham said that there is, as yet, no clear explanation for the phenomenon.[18] GalleryReferences1. ^1 2 3 {{citation | title=Illustrated Guide to Astronomical Wonders: From Novice to Master Observer | first1=Robert | last1=Thompson | first2=Barbara | last2=Thompson | publisher=O'Reilly Media, Inc. | series=DIY science | year=2007 | isbn=978-0596526856 | page=431 | url=https://books.google.com/books?id=ymt9nj_uPhwC&pg=PA431 }}
2. ^1 {{Cite journal | last=Cuffey | first=James | title=The Galactic Clusters NGC 6649 and NGC 6694 | journal=Astrophysical Journal | volume=92 | pages=303 | year=1940 | bibcode=1940ApJ....92..303C | doi=10.1086/144220 }}
3. ^1 {{Cite web | title=M26 - Open Cluster | last=Merrifield | first=Michael | date=Oct 2, 2015 | website=Deep Sky Videos | publisher=University of Nottingham/University of Sheffield | url=http://www.deepskyvideos.com/videos/messier/M26.html | access-date=March 29, 2016 }}
4. ^1 2 {{Citation | last1=Kharchenko | first1=N. V. | last2=Piskunov | first2=A. E. | last3=Röser | first3=S. | last4=Schilbach | first4=E. | last5=Scholz | first5=R.-D. | display-authors=1 | title=Astrophysical parameters of Galactic open clusters | journal=Astronomy and Astrophysics | volume=438 | issue=3 | pages=1163–1173 | year=2005 | bibcode=2005A&A...438.1163K | arxiv=astro-ph/0501674 | doi=10.1051/0004-6361:20042523 | postscript=. }}
5. ^1 2 3 4 {{Citation | display-authors=1 | last1=Wu | first1 = Zhen-Yu | last2=Zhou | first2 = Xu | last3=Ma | first3 = Jun | last4=Du | first4 = Cui-Hua | title=The orbits of open clusters in the Galaxy | journal=Monthly Notices of the Royal Astronomical Society | 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 | postscript=. }}
6. ^1 2 {{citation | title=Shape parameters of Galactic open clusters | last1=Kharchenko | first1=N. V. | last2=Berczik | first2=P. | last3=Petrov | first3=M. I. | last4=Piskunov | first4=A. E. | last5=Röser | first5=S. | last6=Schilbach | first6=E. | last7=Scholz | first7=R. -D. | display-authors=1 | journal=Astronomy and Astrophysics | postscript=. | volume=495 | issue=3 | pages=807–818 | date=March 2009 | doi=10.1051/0004-6361/200810407 | bibcode=2009A&A...495..807K | arxiv=0812.3542 }}
7. ^1 {{citation | last1=Piskunov | first1=A. E. | last2=Schilbach | first2=E. | last3=Kharchenko | first3=N. V. | last4=Röser | first4=S. | last5=Scholz | first5=R.-D. | display-authors=1 | 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=. }}
8. ^1 {{citation | display-authors=1 | title=Red giants in open clusters. XIII. Orbital elements of 156 spectroscopic binaries | last1=Mermilliod | first1=J. -C. | last2=Andersen | first2=J. | last3=Latham | first3=D. W. | last4=Mayor | first4=M. | journal=Astronomy and Astrophysics | postscript=. | volume=473 | issue=3 | date=October 2007 | pages=829–845 | doi=10.1051/0004-6361:20078007 | bibcode=2007A&A...473..829M }}
9. ^1 2 {{citation | title=Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System | volume=3 | series=Dover books on astronomy | first1=Robert | last1=Burnham | publisher=Courier Corporation | year=1978 | isbn=978-0486236735 | page=1756 | url=https://books.google.com/books?id=tBQoCSRdLAAC&pg=PA1756 }}
}}External links- Messier 26, SEDS Messier pages
- {{WikiSky|NGC 6694}}
{{Sky|18|45.2|00|-|09|24|00|5000}}{{Messier objects}} 6 : Open clusters|Carina–Sagittarius Arm|Scutum (constellation)|Messier objects|NGC objects|Astronomical objects discovered in 1764 |