Local Sheet
Nearby small galaxy filement
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 10.4 megaparsecs (34 million light-years; 3.2×1020 kilometres), 465 kiloparsecs (1.52 million light-years; 1.43×1019 kilometres) 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 is only 40 km⋅s−1 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 (Local 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 ~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 so-called Council of Giants is a ring of twelve large galaxies surrounding the Local Group in the Local Sheet, with a radius of 3.746 Mpc (12.22 Mly) and its center located at 810 kpc (2.6 Mly) away from the Sun. 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.
| Catalog ID | Name | Constellation | Distance (Mly) | Stellar mass * |
|---|---|---|---|---|
| NGC 253 | Sculptor Galaxy | Sculptor | 11 | 10.805 |
| PGC 9892 | Maffei 1 | Cassiopeia | 11 | 10.928 |
| PGC 10217 | Maffei 2 | Cassiopeia | 11 | 10.493 |
| IC 342 | Camelopardalis | 11 | 10.302 | |
| 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 | 11.169 |
| NGC 4945 | Centaurus | 12 | 10.528 | |
| ESO 97-G13 | Circinus Galaxy | Circinus | 14 | 10.559 |
* The mass is given as the logarithm (base unspecified) of the mass in solar masses.
01Location
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 10 Mpc (33 Mly) 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.
Sources and credits
This article is adapted from the Wikipedia article “Local Sheet”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- LocalSheet.jpg by Hd93129, CC BY-SA 4.0
- Council of giants (front view).png by Piquito veloz, CC BY-SA 4.0
- Local Group and nearest galaxies.jpg by Antonio Ciccolella, CC BY-SA 4.0
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