Local Sheet
Observation data (Epoch )
Brightest memberLocal Group
Major axis17 Mly (5 Mpc) [1]
Minor axis1.5 Mly (0.5 Mpc) [1]
Redshift0.00
Distance0 Mly (0 Mpc)

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.[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 is only 40 km⋅s−1 in the radial direction.[2] 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).[4] The Local Sheet forms a wall of galaxies delineating one boundary of the Local Void.[5]

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.[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 so-called Council of Giants is a ring of twelve large galaxies surrounding the Local Group in the Local Sheet, with a radius of 3.75 Mpc (12.2 Mly).[4] 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.

Local Sheet (top view)
Galaxies in the "Council of Giants"[4]
Catalog IDNameConstellationDistance (Mly)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 (base unspecified) of the mass in solar masses.

See also

References

  1. 1 2 3 4 "Milky Way amidst a 'Council of Giants'". Science Daily. 11 March 2014.
  2. 1 2 3 4 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. S2CID 14738309.
  3. 1 2 3 Tully, R. Brent (May 2008), "The Local Void is Really Empty", Dark Galaxies and Lost Baryons, Proceedings of the International Astronomical Union, IAU Symposium, vol. 244, pp. 146–151, arXiv:0708.0864, Bibcode:2008IAUS..244..146T, doi:10.1017/S1743921307013932, S2CID 119643726
  4. 1 2 3 4 McCall, Marshall L. (29 April 2013). "A Council of Giants". Monthly Notices of the Royal Astronomical Society (published 10 March 2014). 440 (1): 405–426. arXiv:1403.3667. Bibcode:2014MNRAS.440..405M. doi:10.1093/mnras/stu199.
  5. ↑ Shaya, Ed J.; Tully, R. Brent (December 2013). "The Formation of the Local Group Planes of Galaxies". Monthly Notices of the Royal Astronomical Society. Oxford University Press. Royal Astronomical Society. 436 (3): 2096–2119. arXiv:1307.4297. Bibcode:2013MNRAS.436.2096S. doi:10.1093/mnras/stt1714.
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