| 词条 | Canes Venatici I (dwarf galaxy) |
| 释义 |
| image = | caption = | name = Canes Venatici Dwarf Galaxy[1] | epoch = J2000 | type = dSph | ra = {{RA|13|28|03.5}}[1] | dec = {{DEC|+33|33|21}}[1] | dist_ly = {{nowrap|711 ± 33 kly}} {{nowrap|(218 ± 10 kpc)}} [4] 685{{±|23|16}} kly {{nowrap|(210{{±|7|5}} kpc)}}[2] | z = | appmag_v = 13.9 ± 0.5[6] | size_v = 17.8 ± 0.8′[7] | constellation name = Canes Venatici | names =CVn Dwarf Galaxy,[1] PGC 4689223 }}Canes Venatici I or CVn I is a dwarf spheroidal galaxy situated in the Canes Venatici constellation and discovered in 2006 in the data obtained by Sloan Digital Sky Survey.[3] It is one of the most distant known satellites of the Milky Way as of 2011 together with Leo I and Leo II.[3] The galaxy is located at a distance of about 220 kpc from the Sun and is moving away from the Sun at a velocity of about 31 km/s.[11] It is classified as a dwarf spheroidal galaxy (dSph) meaning that it has an elliptical (ratio of axes ~ 2.5:1) shape with the half-light radius of about 550 pc.[3][4] CVn I is a relatively faint satellite of the Milky Way—its integrated luminosity is about 230,000 times that of the Sun (absolute visible magnitude of about −8.6).[4] However, its mass is about 27 million solar masses, which means that the galaxy's mass to light ratio is around 220. A high mass to light ratio implies that CVn I is dominated by the dark matter.[5] The stellar population of CVn I consists mainly of old stars formed more than 10 billion years ago. The metallicity of these old stars is also very low at {{nowrap|[Fe/H] ≈ −2.08 ± 0.02}}, which means that they contain 110 times less heavy elements than the Sun.[6] There are also about 60 RR Lyrae stars.[2] The galaxy also contains a small fraction of younger (1–2 billion years old) more metal-rich ({{nowrap|[Fe/H] ≈ −1.5}}) stars, which account for about 5% of its mass and 10% of its light. These younger stars are concentrated in the center of the galaxy.[7] There is currently no star formation in CVn I and the measurements have so far failed to detect neutral hydrogen in it—the upper limit is 30,000 solar masses.[8] References1. ^1 2 3 {{cite simbad|title=NAME CVn I dSph|accessdate=2011-11-21}} 2. ^1 {{Cite journal | last1 = Kuehn | first1 = C. | last2 = Kinemuchi | first2 = K. | last3 = Ripepi | first3 = V. | last4 = Clementini | first4 = G. | last5 = Dall'Ora | first5 = M. | last6 = Di Fabrizio | first6 = L. | last7 = Rodgers | first7 = C. T. | last8 = Greco | first8 = C. | last9 = Marconi | first9 = M. | last10 = Musella | doi = 10.1086/529137 | first10 = I. | last11 = Smith | first11 = H. A. | last12 = Catelan | first12 = M. R. | last13 = Beers | first13 = T. C. | last14 = Pritzl | first14 = B. J. | title = Variable Stars in the Newly Discovered Milky Way Dwarf Spheroidal Satellite Canes Venatici I | journal = The Astrophysical Journal | volume = 674 | issue = 2 | pages = L81 | year = 2008 | pmid = | pmc = |arxiv = 0709.3281 |bibcode = 2008ApJ...674L..81K }} 3. ^1 2 3 {{Cite journal | last1 = Zucker | first1 = D. B. | last2 = Belokurov | first2 = V. | last3 = Evans | first3 = N. W. | last4 = Wilkinson | first4 = M. I. | last5 = Irwin | first5 = M. J. | last6 = Sivarani | first6 = T. | last7 = Hodgkin | first7 = S. | last8 = Bramich | first8 = D. M. | last9 = Irwin | first9 = J. M. | last10 = Gilmore | doi = 10.1086/505216 | first10 = G. | last11 = Willman | first11 = B. | last12 = Vidrih | first12 = S. | last13 = Fellhauer | first13 = M. | last14 = Hewett | first14 = P. C. | last15 = Beers | first15 = T. C. | last16 = Bell | first16 = E. F. | last17 = Grebel | first17 = E. K. | last18 = Schneider | first18 = D. P. | last19 = Newberg | first19 = H. J. | last20 = Wyse | first20 = R. F. G. | last21 = Rockosi | first21 = C. M. |author-link21=Constance M. Rockosi| last22 = Yanny | first22 = B. | last23 = Lupton | first23 = R. | last24 = Smith | first24 = J. A. | last25 = Barentine | first25 = J. C. | last26 = Brewington | first26 = H. | last27 = Brinkmann | first27 = J. | last28 = Harvanek | first28 = M. | last29 = Kleinman | first29 = S. J. | last30 = Krzesinski | first30 = J. | title = A New Milky Way Dwarf Satellite in Canes Venatici | journal = The Astrophysical Journal | volume = 643 | issue = 2 | pages = L103 | year = 2006 | pmid = | pmc = |arxiv = astro-ph/0604354 |bibcode = 2006ApJ...643L.103Z }} 4. ^1 2 {{Cite journal | last1 = Martin | first1 = N. F. | last2 = De Jong | first2 = J. T. A. | last3 = Rix | first3 = H. W. | doi = 10.1086/590336 | title = A Comprehensive Maximum Likelihood Analysis of the Structural Properties of Faint Milky Way Satellites | journal = The Astrophysical Journal | volume = 684 | issue = 2 | pages = 1075 | year = 2008 | pmid = | pmc =| ref =CITEREFMartinDe_JongRix2008|arxiv = 0805.2945 |bibcode = 2008ApJ...684.1075M }} 5. ^1 {{Cite journal | last1 = Simon | first1 = J. D. | last2 = Geha | first2 = M. | doi = 10.1086/521816 | title = The Kinematics of the Ultra‐faint Milky Way Satellites: Solving the Missing Satellite Problem | journal = The Astrophysical Journal | volume = 670 | pages = 313 | year = 2007 | pmid = | pmc = |arxiv = 0706.0516 |bibcode = 2007ApJ...670..313S }} 6. ^{{Cite journal | last1 = Kirby | first1 = E. N. | last2 = Simon | first2 = J. D. | last3 = Geha | first3 = M. | last4 = Guhathakurta | first4 = P. | last5 = Frebel | first5 = A. | title = Uncovering Extremely Metal-Poor Stars in the Milky Way's Ultrafaint Dwarf Spheroidal Satellite Galaxies | doi = 10.1086/592432 | journal = The Astrophysical Journal | volume = 685 | pages = L43 | year = 2008 | pmid = | pmc = |arxiv = 0807.1925 |bibcode = 2008ApJ...685L..43K }} 7. ^1 {{Cite journal | last1 = Martin | first1 = N. F. | last2 = Coleman | first2 = M. G. | last3 = De Jong | first3 = J. T. A. | last4 = Rix | first4 = H. W. | last5 = Bell | first5 = E. F. | last6 = Sand | first6 = D. J. | last7 = Hill | first7 = J. M. | last8 = Thompson | first8 = D. | last9 = Burwitz | first9 = V. | last10 = Giallongo | first10 = E. | last11 = Ragazzoni | first11 = R. | last12 = Diolaiti | first12 = E. | last13 = Gasparo | first13 = F. | last14 = Grazian | first14 = A. | last15 = Pedichini | first15 = F. | last16 = Bechtold | first16 = J. | title = A Deep Large Binocular Telescope View of the Canes Venatici I Dwarf Galaxy | doi = 10.1086/525559 | journal = The Astrophysical Journal | volume = 672 | pages = L13 | year = 2008 | pmid = | pmc = |arxiv = 0709.3365 |bibcode = 2008ApJ...672L..13M }} 8. ^{{Cite journal | last1 = Grcevich | first1 = J. | last2 = Putman | first2 = M. E. | doi = 10.1088/0004-637X/696/1/385 | title = H I in Local Group Dwarf Galaxies and Stripping by the Galactic Halo | journal = The Astrophysical Journal | volume = 696 | pages = 385 | year = 2009 | pmid = | pmc = |arxiv = 0901.4975 |bibcode = 2009ApJ...696..385G }} External links
6 : Dwarf spheroidal galaxies|Local Group|Milky Way Subgroup|Canes Venatici|Principal Galaxies Catalogue objects|Astronomical objects discovered in 2006 |
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