| 词条 | Local Sheet | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 释义 |
| name = Local Sheet | image = | caption = | credit = | epoch = | constellation = | ra = | dec = | brightest_member = Local Group | member_no = | major_axis_mpc = {{convert|17|Mly|Mpc|0|abbr=on|lk=on}} [1] | minor_axis_mpc = {{convert|1.5|Mly|Mpc|1|abbr=on|lk=on}} [1] | redshift = 0.00 | distance = {{convert|0|Mly|Mpc|0|abbr=on|lk=on}} | mass = | luminosity = | flux = | other_names = }} The Local Sheet in astronomy is a nearby extragalactic region of space where the Milky Way, the members of the Local Group and other galaxies share a similar peculiar velocity. This region lies within a radius of about {{convert|7|Mpc|Mly|abbr=on|lk=on}},[4] {{convert|1.5|Mly|Mpc|abbr=on|order=flip}} thick,[1] and galaxies beyond that distance show markedly different velocities.[4] The Local Group has only a relatively small peculiar velocity of {{Val|66|ul=km.s-1}} with respect to the Local Sheet. Typical velocity dispersion of galaxies is only {{Val|40|u=km.s-1}} in the radial direction. Nearly all nearby bright galaxies belong to the Local Sheet.[1] The Local Sheet is part of the Local Volume and is in the Virgo Supercluster (Local Supercluster).[9] The Local Sheet forms a wall of galaxies delineating one boundary of the Local Void.[10] A significant component of the mean velocity of the galaxies in the Local Sheet appears as the result of the gravitational attraction of the Virgo Cluster of galaxies, resulting in a peculiar motion ~{{Val|185|u=km.s-1}} toward the cluster. A second component is directed away from the center of the Local Void; an expanding region of space spanning an estimated {{convert|45|Mpc|Mly|abbr=on}} that is only sparsely populated with galaxies.[4] This component has a velocity of {{Val|259|u=km.s-1}}. The Local Sheet is inclined 8° from the Local Supercluster (Virgo Supercluster).[1] The so-called Council of Giants is a ring of twelve large galaxies surrounding the Local Group in the Local Sheet, with a radius of {{convert|3.75|Mpc|Mly|abbr=on}}.[1] Ten of these are spirals, while the remaining two are ellipticals. The two ellipticals (Maffei 1 and Centaurus A) lie on opposite sides of the Local Group, and their formation may have prompted the development of the Local Group. The Local Sheet's own development outlines a concentration of dark matter in a filament.[1]
See also
References1. ^1 2 3 {{cite journal |title=A Council of Giants |first=Marshall L. |last=McCall |date=29 April 2013 |publication-date=10 March 2014 |doi=10.1093/mnras/stu199 |url=http://mnras.oxfordjournals.org/content/440/1/405 |journal=Monthly Notices of the Royal Astronomical Society |volume=440 |issue=1 |pages=405–426 |arxiv=1403.3667 |bibcode=2014MNRAS.440..405M}} [2][3][4]2. ^1 2 3 {{citation | last1=Tully | first1=R. Brent | contribution=The Local Void is Really Empty | title=Dark Galaxies and Lost Baryons, Proceedings of the International Astronomical Union, IAU Symposium | volume=244 | pages=146–151 |date=May 2008 | doi=10.1017/S1743921307013932 | bibcode=2008IAUS..244..146T | arxiv=0708.0864}} 3. ^1 2 3 4 5 {{cite news |url=https://www.sciencedaily.com/releases/2014/03/140311100606.htm |title=Milky Way amidst a 'Council of Giants' |date=11 March 2014 |publisher=Science Daily}} 4. ^1 {{cite journal |title= The Formation of the Local Group Planes of Galaxies |authors= Shaya, Ed J.; Tully, R. Brent; |journal= Monthly Notices of the Royal Astronomical Society |volume= 436 |issue= 3 |pages= 2096–2119 |date= December 2013 |publisher= Oxford University Press |agency= Royal Astronomical Society |arxiv= 1307.4297 |doi= 10.1093/mnras/stt1714 |bibcode= 2013MNRAS.436.2096S}} }}{{Earth's location}} 3 : Large-scale structure of the cosmos|Galaxy superclusters|Virgo Supercluster |
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