| 词条 | NGC 7013 | |
| 释义 |
| name = NGC 7013 | image =NGC 7013 hst 06359 606.png | image_size =250px | caption = Hubble image of NGC 7013. | epoch = J2000 | type = SA(r)0/a, LINER[1] | ra = {{RA|21|03|33.6}}[1] | dec = {{DEC|29|53|51}}[1] | dist_ly = 37/41.4 (estimated) Mly | z = 0.002598/779 km/s[1] | appmag_v = 12.40[1] | size_v = 4.0 × 1.4[1] | constellation name = Cygnus | names = UGC 11670, CGCG 491-2, IRAS 21014+2941, MCG 5-49-1, PGC 66003[1] |size=~43,680NGC 7013 is a relatively nearby spiral or lenticular galaxy[8][9] estimated to be around 37 to 41.4 million light-years away from Earth[2][3] in the constellation of Cygnus.[4] NGC 7013 was discovered by English astronomer William Herschel on July 17, 1784 and was also observed by his son, astronomer John Herschel on September 15, 1828.[5] Physical characteristicsNGC 7013 is tilted 90° to the Earth's line of sight,[6] allowing its structure to be seen. However, NGC 7013 is classified as either as a spiral galaxy with tightly wound arms or as a lenticular galaxy.[8][16] NGC 7013 is also considered part of a class of galactic nuclei that is defined by their spectral line emissions, called low-ionization nuclear emission-line region galaxies or LINERs.[7][8] The galaxy appears to have two rings in its structure. The inner ring appears to completely disconnect from the central bulge while the stars in the outer ring appear to have very little spiral pattern.[9] Optical images of NGC 7013 show that it has a small bulge[10] with a bright inner ring and a faint disk both crossed by dust lanes.[9] A longer exposure of the galaxy made by the Palomar Observatory-National Geographic Sky Survey shows an extended disk around the bulge and the inner ring. The disk shows little structure except for a faint, thin spiral-like feature running through the galaxy.[11] HI distributionThe neutral atomic hydrogen distribution in NGC 7013 is mostly located in the two rings. In between the two rings there is a very low concentration of interstellar medium. The low level of neutral atomic hydrogen in the disk of NGC 7013 and the reddish color of the galaxy suggests that the gas content of the galactic disc has fallen below the threshold at which star formation is likely to take place. The small bulge-to-disk ratio and the slow rotation velocity show that NGC 7013 is a low-mass, low-density galaxy unlike the more luminous, typical lenticular galaxies. The galaxy may thus be a former late-type spiral galaxy which have exhausted most of its interstellar gas, either by star formation or by internal sweeping.[11] GallerySee also
References1. ^1 2 3 4 5 6 {{cite web | title=NASA/IPAC Extragalactic Database | work=Results for NGC 7013 | url=http://nedwww.ipac.caltech.edu/ | accessdate=2017-05-21}} 2. ^{{Cite journal|title=Confrontation of Modified Newtonian Dynamics with the rotation curves of early-type disc galaxies|journal=Monthly Notices of the Royal Astronomical Society|volume=379|issue=2|pages=702–710|doi=10.1111/j.1365-2966.2007.11981.x|year=2007|last1=Sanders|first1=R. H.|last2=Noordermeer|first2=E.|bibcode=2007MNRAS.379..702S|arxiv = astro-ph/0703352 }} 3. ^{{Cite journal|last=B.A. Williams|first=F. J. Kerr|date=21 December 1977|title=H I OBSERVATIONS OF ELLIPTICAL GALAXIES|bibcode=1978ApJ...222..800K|journal=The Astrophysical Journal |volume=222|pages=15|via=|doi=10.1086/156199}} 4. ^{{Cite web|url=https://dso-browser.com/deep-sky/8200/ngc-7013/galaxy|title=Galaxy NGC 7013 · Deep Sky Objects Browser|last=Rojas|first=Sebastián García|website=DSO Browser|language=en|access-date=2017-05-18}} 5. ^{{Cite web|url=http://cseligman.com/text/atlas/ngc70.htm|title=New General Catalog Objects: NGC 7000 – 7049|website=cseligman.com|language=en-US|access-date=2017-04-15}} 6. ^{{Cite journal|last=V. L. Afanasiev|first=O. K. Sil’chenko|date=13 December 2001|title=Chemically distinct nuclei and circumnuclear rings in lenticular galaxies NGC 4429 and NGC 7013|url=https://www.aanda.org/articles/aa/pdf/2002/13/aa1909.pdf|journal=Astronomy and Astrophysics|volume=385|pages=1–13|via=|bibcode=2002A&A...385....1S|doi=10.1051/0004-6361:20020143}} 7. ^1 {{Cite web|url=http://www.kopernik.org/images/archive/n7013.htm|title=NGC 7013, Spiral Galaxy|last=Normandin|first=George P.|date=|website=www.kopernik.org|archive-url=|archive-date=|dead-url=|access-date=2017-05-21}} 8. ^{{Cite web|url=http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=NGC+7013&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES|title=Your NED Search Results|website=ned.ipac.caltech.edu|access-date=2017-09-03}} 9. ^1 2 {{Cite web|url=http://www.kentbiggs.com/images/galaxies/N7013-2.htm|title=AstroImaging by Kent Biggs|website=www.kentbiggs.com|access-date=2017-05-21}} 10. ^{{cite journal|last1=Prieto|first1=M.|last2=Aguerri|first2=J. A. L.|last3=Varela|first3=A. M.|last4=Muñoz-Tuñón|first4=C.|title=Optical surface photometry of a sample of disk galaxies|journal=Astronomy & Astrophysics|date=15 February 2001|volume=367|issue=2|pages=405–427|doi=10.1051/0004-6361:20000426|arxiv=astro-ph/0012110|bibcode=2001A&A...367..405P}} 11. ^1 2 3 {{Cite journal |date=27 October 1983 |title=Distribution and motions of atomic hydrogen in lenticular galaxies II. NGC 7013|url=http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1984A%26A...133..127K&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf |journal=Astronomy and Astrophysics |volume=133 |pages=127|bibcode=1984A&A...133..127S}} External links{{WikiSky}} 8 : Unbarred spiral galaxies|LINER galaxies|Cygnus (constellation)|NGC objects|UGC objects|Principal Galaxies Catalogue objects|Lenticular galaxies|Astronomical objects discovered in 1784 |
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