| 词条 | Fornax Dwarf |
| 释义 |
| image = Fornax dwarf galaxy.jpg | image_size = 260px | caption = The Fornax dwarf galaxy. Credit: ESO/Digitized Sky Survey 2 | name = Fornax Dwarf Spheroidal | epoch = J2000 | type = dE0[1] | ra = {{RA|02|39|59.3}}[1] | dec = {{DEC|-34|26|57}}[1] | dist_ly = 460 ± 30 kly (140 ± 10 kpc)[2][3] | z = 53 ± 9 km/s[1] | appmag_v = 9.3[1] | size_v = 17′.0 × 12′.6[1] | constellation name = Fornax | notes = has 6 globular clusters | names = Fornax dSph,[4] Fornax Dwarf Elliptical,[4] Fornax Dwarf Galaxy,[4] Fornax dE,[4] PGC 10074 / 10093[1] }} The Fornax Dwarf Spheroidal is an elliptical dwarf galaxy in the constellation Fornax that was discovered in 1938 by Harlow Shapley. He discovered it while he was in South Africa on photographic plates taken by the 24 inch (61 cm) Bruce refractor at Boyden Observatory, shortly after he discovered the Sculptor Dwarf Galaxy.[5] The galaxy is a satellite of the Milky Way and contains six globular clusters; the largest, NGC 1049, was discovered before the galaxy itself. The galaxy is also receding from the Milky Way at 53 km/s. It mostly contains population II stars. Globular clustersUsing the Hubble Space Telescope, scientists derived a color-magnitude diagram for Fornax 4, a globular cluster within this galaxy. Unlike the globular clusters Fornax 1, 2, 3, and 5, which have horizontal branches across a wide range of colors and include RR Lyrae variables, Fornax 4 is found to have only red in its horizontal branch. Fornax 4 is also ~3 Gyr younger than the other globular clusters. The color-magnitude diagram of Fornax 4 has a strong similarity to "young" galactic globular Ruprecht 106.[6] It is not known why spheroidals allow the formation of globular clusters like Fornax 4 and Terzan 7 (of Sagittarius dwarf) long after globular clusters ceased to form in the main body of the Galactic halo. Another possibility is that "young" globular clusters of the outer halo like Ruprecht 106 were originally formed in now defunct dwarf spheroidals.[7] References1. ^1 2 3 4 5 6 {{cite web | title=NASA/IPAC Extragalactic Database | work=Results for Fornax Dwarf Spheroidal | url=http://nedwww.ipac.caltech.edu/ | accessdate=2006-11-29 }} 2. ^{{cite journal |author1=I. D. Karachentsev |author2=V. E. Karachentseva |author3=W. K. Hutchmeier |author4=D. I. Makarov | title=A Catalog of Neighboring Galaxies | journal=Astronomical Journal | date=2004 | volume=127 | issue=4 | pages=2031–2068 | bibcode=2004AJ....127.2031K | doi=10.1086/382905}} 3. ^{{cite journal |author1=Karachentsev, I. D. |author2=Kashibadze, O. G. | title=Masses of the local group and of the M81 group estimated from distortions in the local velocity field | journal=Astrophysics | date=2006 | volume=49 | issue=1 | pages=3–18 | bibcode=2006Ap.....49....3K | doi=10.1007/s10511-006-0002-6 }} 4. ^1 2 3 {{cite simbad | title=NAME Fornax Dwarf Spheroidal | accessdate=2006-11-29}} 5. ^{{cite journal | author = Shapley H | date = 1938 | title = Two Stellar Systems of a New Kind | url = | journal = Nature | volume = 142 | issue = 3598| pages = 715–6 | bibcode = 1938Natur.142..715S | doi=10.1038/142715b0}} 6. ^{{cite journal |author=Buonanno, R. |display-authors=etal |title=HST photometry of the fornax dSph galaxy: cluster 4 and its field |journal=The Astronomical Journal |volume=118 |issue=4 |pages=1671–1683 |arxiv=astro-ph/9907073 |date=1 October 1999 |url=http://iopscience.iop.org/1538-3881/118/4/1671/fulltext/ |bibcode = 1999astro.ph..7073B |doi=10.1086/301034}} 7. ^{{Cite journal | last1 = van den Bergh | first1 = Sidney | authorlink1 = Sidney van den Bergh | title = Updated Information on the Local Group | date = April 2000 | journal = The Publications of the Astronomical Society of the Pacific | volume = 112 | issue = 770 | bibcode = 2000PASP..112..529V | pages = 529–536 | doi = 10.1086/316548 | postscript = |arxiv = astro-ph/0001040 }} External links
7 : Dwarf galaxies|Dwarf elliptical galaxies|Local Group|Milky Way Subgroup|Fornax (constellation)|Principal Galaxies Catalogue objects|Astronomical objects discovered in 1938 |
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