NGC 3945 explained

Epoch:J2000
Constellation Name:Ursa Major
Ra:[1]
H Radial V:1242 ± 22 km/s
Z:0.004153
Dist Ly:[2]
Type:(R)SB(rs)0+
Appmag V:10.75[3]
Appmag B:11.70
Names:[4]

NGC 3945 is a barred lenticular galaxy in the constellation Ursa Major. It was discovered on March 19, 1790, by the astronomer William Herschel.[5]

NGC 3945 has a complex structure, with two concentric bars and a pseudobulge.[2] Unlike classical bulges which are like miniature elliptical galaxies, pseudobulges have features similar to disk galaxies, including a flattened structure and significant rotation.[6] It is classified as a LINER galaxy.[2] The formation history of NGC 3945 is likely quite complex, with the pseudo-bulge being formed gradually from disk material, while bulges (spheroidal components) would have formed from violent merger events.[2]

Unlike galaxies with similar velocity dispersions and luminosities, the central black hole of NGC 3945 has an unusually low mass, estimated to be around . However, it is also possible that NGC 3945 has no central black hole at all.[7]

Notes and References

  1. 10.1086/498708 . Skrutskie . Michael F. . Cutri . Roc M. . Stiening . Rae . Weinberg . Martin D. . Schneider . Stephen E. . Carpenter . John M. . Beichman . Charles A. . Capps . Richard W. . Chester . Thomas . Elias . Jonathan H. . Huchra . John P. . Liebert . James W. . Lonsdale . Carol J. . Monet . David G. . Price . Stephan . Seitzer . Patrick . Jarrett . Thomas H. . Kirkpatrick . J. Davy . Gizis . John E. . Howard . Elizabeth V. . Evans . Tracey E. . Fowler . John W. . Fullmer . Linda . Hurt . Robert L. . Light . Robert M. . Kopan . Eugene L. . Marsh . Kenneth A. . McCallon . Howard L. . Tam . Robert . Van Dyk . Schuyler D. . Wheelock . Sherry L. . The Two Micron All Sky Survey (2MASS) . The Astronomical Journal . 1 February 2006 . 131 . 2 . 1163–1183 . 2006AJ....131.1163S . 18913331 . 0004-6256 . free .
  2. 10.1093/mnras/stw1868. Complex central structures suggest complex evolutionary paths for barred S0 galaxies. 2016. Dullo. Bililign T.. Martínez-Lombilla. Cristina. Knapen. Johan H.. Monthly Notices of the Royal Astronomical Society. 462. 4. 3800–3811. free . 1608.03539.
  3. Web site: Search specification: NGC 3945. HyperLeda. Université Claude Bernard Lyon 1. 2021-05-18.
  4. NGC 3945. 2021-05-18.
  5. Web site: New General Catalogue objects: NGC 3900 - 3949. Seligman, Courtney. cseligman.com. 2021-05-18.
  6. 10.1088/0004-6256/136/2/773. The Structure of Classical Bulges and Pseudobulges: The Link Between Pseudobulges and Sérsic Index. 2008. Fisher. David B.. Drory. Niv. The Astronomical Journal. 136. 2. 773–839. 0805.4206. 2008AJ....136..773F. 16126374.
  7. 10.1088/0004-637X/695/2/1577. A Quintet of Black Hole Mass Determinations. 2009. Gültekin. Kayhan. Richstone. Douglas O.. Gebhardt. Karl. Lauer. Tod R.. Pinkney. Jason. Aller. M. C.. Bender. Ralf. Dressler. Alan. Faber. S. M.. Filippenko. Alexei V.. Green. Richard. Ho. Luis C.. Kormendy. John. Siopis. Christos. The Astrophysical Journal. 695. 2. 1577–1590. 0901.4162. 2009ApJ...695.1577G. 14365610.

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