Local Sheet


The Local Sheet or the Coma–Sculptor Cloud is a nearby galaxy filament and an 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 diameter of about, thick, and galaxies beyond that distance show markedly different velocities. The Local Group has only a relatively small peculiar velocity of with respect to the Local Sheet. Typical velocity dispersion of galaxies is only in the radial direction. Nearly all nearby bright galaxies belong to the Local Sheet. The Local Sheet is part of the Local Volume and is in the Virgo Supercluster. The Local Sheet forms a wall of galaxies delineating one boundary of the Local Void.
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 ~ toward the cluster. A second component is directed away from the center of the Local Void; an expanding region of space spanning an estimated that is only sparsely populated with galaxies. This component has a velocity of. The Local Sheet is inclined 8° from the Local Supercluster.
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 and its center located at away from the Sun. Ten of these are spirals, while the remaining two are ellipticals. The two ellipticals lie on opposite sides of the Local Group.
Catalog IDNameConstellationDistance Stellar mass *
NGC 253Sculptor GalaxySculptor1110.805
PGC 9892Maffei 1Cassiopeia1110.928
PGC 10217Maffei 2Cassiopeia1110.493
IC 342 Camelopardalis1110.302
NGC 3031M 81Ursa Major1210.905
NGC 3034M 82Ursa Major1110.573
NGC 4736M 94Canes Venatici1510.458
NGC 4826M 64Coma Berenices1610.496
NGC 5236M 83Hydra1610.642
NGC 5128Centaurus ACentaurus1111.169
NGC 4945 Centaurus1210.528
ESO 97-G13Circinus GalaxyCircinus1410.559

* The mass is given as the logarithm of the mass in solar masses.

Location

The Local Sheet is the co-moving part of the Coma-Sculptor Cloud, which was identified and described in 1987 by astronomer Brent Tully with colleague Richard Fisher in his book The Nearby Galaxies Atlas as Cloud 14. It is a huge prolate, filament and is mostly host to late-type galaxies, in contrast to the Virgo Cluster, in which more than half of the giant galaxies are early-type galaxies.
Tully maintains that the Coma-Sculptor Cloud and the Local Sheet do not quite overlap, as the Local Sheet comprises only the co-moving part of the Coma-Sculptor Cloud. McCall considers the two terms synonymous, referring to one and the same region.