Local Sheet

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Local Sheet
Observation data (Epoch )
Brightest member Local Group
Major axis 17 Mly (5 Mpc) [1]
Minor axis 1.5 Mly (0.5 Mpc) [1]
Redshift 0.00
Mly (0 Mpc)
See also: Galaxy groups, Galaxy clusters, List of superclusters

The Local Sheet in astronomy is a nearby region of the observable universe where the Milky Way, the members of the Local Group and other galaxies share a similar peculiar velocity.[2] This region lies within a radius of about 7 Mpc (23 Mly),[3] 0.46 Mpc (1.5 Mly) thick,[1] and galaxies beyond that distance show markedly different velocities.[3] The Local Group has only a relatively small peculiar velocity of 66 km s−1 with respect to the Local Sheet. Typical velocity dispersion of galaxies within the Local Sheet is only 40 km s−1 in the radial direction.[2] 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).[4]

A significant component of the mean velocity of the galaxies in the Local Sheet comes as the result of the gravitational attraction of the Virgo Cluster of galaxies. This results in a peculiar motion of about 185 km s−1 toward the cluster.[2] A second component is directed away from the center of the Local Void; an expanding region of space spanning an estimated 45 Mpc (150 Mly) that is only sparsely populated with galaxies.[3] This component has a velocity of 259 km s−1.[2] The Local Sheet is inclined 8° from the Local Supercluster (Virgo Supercluster).[4]

The Council of Giants is a ring of fourteen large galaxies surrounding the Local Group in the Local Sheet, with a radius of 3.75 Mpc (12.2 Mly).[4] Twelve of these are spirals, while the remaining two are ellipticals. The two ellipticals 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]


  1. ^ a b c d e "Milky Way amidst a 'Council of Giants'". Science Daily. 11 March 2014. 
  2. ^ a b c d Tully, R. Brent; Shaya, Edward J.; Karachentsev, Igor D.; Courtois, Hélène M.; Kocevski, Dale D.; Rizzi, Luca; Peel, Alan (March 2008). "Our Peculiar Motion Away from the Local Void". The Astrophysical Journal 676 (1): 184–205. arXiv:0705.4139. Bibcode:2008ApJ...676..184T. doi:10.1086/527428. 
  3. ^ a b c Tully, R. Brent (May 2008), "The Local Void is Really Empty", Dark Galaxies and Lost Baryons, Proceedings of the International Astronomical Union, IAU Symposium 244, pp. 146–151, arXiv:0708.0864, Bibcode:2008IAUS..244..146T, doi:10.1017/S1743921307013932 
  4. ^ a b c Marshall L. McCall (April 29, 2013). "A Council of Giants" (published 10 March 2014). arXiv:1403.3667. Bibcode:2014MNRAS.440..405M. doi:10.1093/mnras/stu199.