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NGC 2787
NGC 2787
	NGC 2787 as observed by the Hubble Space Telescope (HST).
Observation data (J2000 epoch)
Constellation	Ursa Major
Right ascension	09h 19m 18.60430s
Declination	+69° 12′ 11.6429″
Heliocentric radial velocity	627.3±13.2 km/s
Distance	24.17 ± 0.46 Mly (7.41 ± 0.14 Mpc)
Apparent magnitude (V)	11.79
Apparent magnitude (B)	12.92
Absolute magnitude (B)	−18.84
Characteristics
Type	SB(r)0+
Mass/Light ratio	50 M☉/L☉
Size	5.5 kpc
Apparent size (V)	2′.530 × 1′.518 (NIR)
Notable features	Barred lenticular; LINER
Other designations
	PGC 26341, UGC 4914

NGC 2787 is a barred lenticular galaxy approximately 24^[3] million light-years away in the northern constellation of Ursa Major. It was discovered on December 3, 1788 by German-born astronomer William Herschel. J. L. E. Dreyer described it as, "bright, pretty large, a little extended 90°, much brighter middle, mottled but not resolved, very small (faint) star involved to the southeast".^[9] The visible galaxy has an angular size of 2.5 × 1.5 arcminutes^[7] or 3.24 × 1.81 arcminutes^[10] and an apparent visual magnitude of 11.8.^[4]

This galaxy is small and isolated^[5] with a morphological classification of SB(r)0⁺,^[6] which indicates a barred spiral (SB) with a ring around the bar (r). Being a lenticular galaxy, it has the large halo of an elliptical galaxy. The disk is inclined at an angle of 58°±3° to the line of sight from the Earth, with the major axis aligned along a position angle of 110°±3°.^[5] The galaxy has an unusually high mass-to-light ratio, much greater than for a typical spiral galaxy.^[5] The distribution of the galaxy's neutral hydrogen forms a clumpy ring with a radius of 10.3 kpc, double that of the visible galaxy, with a mass of 5.5×10⁸ M_☉.^[5] This ring appears misaligned with the central disk.^[11]

NGC 2787 contains a low-ionization nuclear emission-line region (LINER) at its core, which is a type of region that is characterized by its spectral line emission from weakly ionized atoms.^[12] LINERs are very common within lenticular galaxies, with approximately one-fifth of nearby lenticular galaxies containing LINERs.^[13] The supermassive black hole at the center has a mass of 4.1+0.4
−0.5×10⁷ M_☉.^[14] The central region of the galaxy contains dust rings that are tilted with respect to the disk, which may be the result of an encounter with another galaxy.^[11]

References

^ ^a ^b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ van den Bosch, Remco C. E.; et al. (May 2015). "Hunting for Supermassive Black Holes in Nearby Galaxies With the Hobby-Eberly Telescope". The Astrophysical Journal Supplement Series. 218 (1): 13. arXiv:1502.00632. Bibcode:2015ApJS..218...10V. doi:10.1088/0067-0049/218/1/10. S2CID 117876537. 10.
^ ^a ^b Tully, R. Brent; et al. (October 2013). "Cosmicflows-2: The Data". The Astronomical Journal. 146 (4): 25. arXiv:1307.7213. Bibcode:2013AJ....146...86T. doi:10.1088/0004-6256/146/4/86. S2CID 118494842. 86.
^ ^a ^b ^c Véron-Cetty, M.-P.; Véron, P. (2010). "A catalogue of quasars and active nuclei". Astronomy & Astrophysics. 13th. 518. Bibcode:2010A&A...518A..10V. doi:10.1051/0004-6361/201014188. A10.
^ ^a ^b ^c ^d ^e ^f ^g Shostak, G. S. (March 1987). "The distribution of HI in the lenticular galaxy NGC 2787". Astronomy and Astrophysics. 175: 4–8. Bibcode:1987A&A...175....4S.
^ ^a ^b Erwin, Peter; Debattista, Victor P. (June 2013). "Peanuts at an angle: detecting and measuring the three-dimensional structure of bars in moderately inclined galaxies". Monthly Notices of the Royal Astronomical Society. 431 (4): 3060–3086. arXiv:1301.0638. Bibcode:2013MNRAS.431.3060E. doi:10.1093/mnras/stt385. S2CID 54653263.
^ ^a ^b 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. (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708. ISSN 0004-6256. S2CID 18913331.
^ "NASA/IPAC Extragalactic Database". Results for NGC 2787. Retrieved 2006-12-13.
^ Seligman, Courtney. "NGC Objects: NGC 2750 - 2799". Celestial Atlas. Retrieved 2020-09-09.
^ "NGC 2787 - Lenticular Galaxy in Ursa Major". The Sky Live. TheSkyLive.com. Retrieved 25 July 2023.
^ ^a ^b Erwin, Peter; et al. (November 2003). "When Is a Bulge Not a Bulge? Inner Disks Masquerading as Bulges in NGC 2787 and NGC 3945". The Astrophysical Journal. 597 (2): 929–947. arXiv:astro-ph/0310791. Bibcode:2003ApJ...597..929E. doi:10.1086/378189. S2CID 16032205.
^ Ho, L. C.; et al. (1997). "A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies". Astrophysical Journal Supplement. 112 (2): 315–390. arXiv:astro-ph/9704107. Bibcode:1997ApJS..112..315H. doi:10.1086/313041. S2CID 17086638.
^ Ho, L. C.; et al. (1997). "A Search for "Dwarf" Seyfert Nuclei. V. Demographics of Nuclear Activity in Nearby Galaxies". Astrophysical Journal. 487 (2): 568–578. arXiv:astro-ph/9704108. Bibcode:1997ApJ...487..568H. doi:10.1086/304638. S2CID 16742031.
^ Graham, Alister W. (November 2008). "Populating the Galaxy Velocity Dispersion - Supermassive Black Hole Mass Diagram: A Catalogue of (Mbh, σ) Values". Publications of the Astronomical Society of Australia. 25 (4): 167–175. arXiv:0807.2549. Bibcode:2008PASA...25..167G. doi:10.1071/AS08013. S2CID 89905.