|Observation data (Epoch )|
|Brightest member||Local Group|
|Major axis||17 Mly (5 Mpc) |
|Minor axis||1.5 Mly (0.5 Mpc) |
|0 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. This region lies within a radius of about 7 Mpc (23 Mly), 0.46 Mpc (1.5 Mly) thick, and galaxies beyond that distance show markedly different velocities. 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. All nearby bright galaxies belong to the Local Sheet. The Local Sheet is part of the Local Volume and is in the Virgo Supercluster (Local Supercluster).
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. 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. This component has a velocity of 259 km s−1. The Local Sheet is inclined 8° from the Local Supercluster (Virgo Supercluster).
The Council of Giants is a ring of twelve large galaxies surrounding the Local Group in the Local Sheet, with a radius of 3.75 Mpc (12.2 Mly). 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.
|Catalog ID||Name||Constellation||Distance (Mly)||Mass *|
|PGC 9892||Maffei 1||Cassiopeia||11||10.928|
|PGC 10217||Maffei 2||Cassiopeia||11||10.493|
|NGC 3031||M 81||Ursa Major||12||10.905|
|NGC 3034||M 82||Ursa Major||11||10.573|
|NGC 4736||M 94||Canes Venatici||15||10.458|
|NGC 4826||M 64||Coma Berenices||16||10.496|
|NGC 5236||M 83||Hydra||16||10.642|
|NGC 5128||Centaurus A||Centaurus||11||10.528|
|ESO 97-G13||Circinus Galaxy||Circinus||14||10.559|
|NGC 253||Sculptor Galaxy||Sculptor||11||10.805|
* The mass is given as the logarithm of the mass in solar masses.
- "Milky Way amidst a 'Council of Giants'". Science Daily. 11 March 2014.
- 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.
- 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
- 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.