NGC 2787

NGC 2787 is a barred lenticular galaxy approximately 24[3] million light-years away in the northern circumpolar 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[7] and an apparent visual magnitude of 11.8.[4]

NGC 2787
NGC 2787 as observed by the Hubble Space Telescope (HST).
Credit: HST/STScI/AURA.
Observation data (J2000 epoch)
ConstellationUrsa Major
Right ascension09h 19m 18.60430s[1]
Declination+69° 12′ 11.6429″[1]
Helio radial velocity627.3±13.2 km/s[2]
Distance24.17 ± 0.46 Mly (7.41 ± 0.14 Mpc)[3]
Apparent magnitude (V)11.79[4]
Apparent magnitude (B)12.92[4]
Absolute magnitude (B)−18.84[5]
Characteristics
TypeSB(r)0+[6]
Mass/Light ratio50[5] M☉/L☉
Size5.5 kpc[5]
Apparent size (V)2′.530 × 1′.518[7] (NIR)
Notable featuresBarred lenticular; LINER
Other designations
PGC 26341, UGC 4914[8]

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.[10]

NGC 2787 contains a low-ionization nuclear emission-line region (LINER) at its core, which is a type of region that is characterized by spectral line emission from weakly ionized atoms.[11] LINERs are very common within lenticular galaxies, with approximately one-fifth of nearby lenticular galaxies containing LINERs.[12] The supermassive black hole at the center has a mass of 4.1+0.4
−0.5×107 M☉.[13] 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.[10]

References
  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. Skrutskie, M. F.; et al. (February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708.
  8. "NASA/IPAC Extragalactic Database". Results for NGC 2787. Retrieved 2006-12-13.
  9. Seligman, Courtney. "NGC Objects: NGC 2750 - 2799". Celestial Atlas. Retrieved 2020-09-09.
  10. 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.
  11. 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.
  12. 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.
  13. 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.


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