NGC 7771 Galaxy Group

NGC 7769, NGC 7770, NGC 7771
NGC 7769, NGC 7770, NGC 7771: Galaxy group in Pegasus; 500 mm Cassegrain f/7.2; SBIG STL11K; 120-20-20-20 min LRGB; Bernese Highlands; © 2011 Radek Chromik

History

The three galaxies were discovered on September 18, 1784 by the German-British astronomer William Herschel with his 18.7 inch reflecting telescope. He cataloged them as II 230 (NGC 7769) and II 231 (NGC 7770 and NGC 7771). Herschels class II stood for faint nebulae. [277, 463]

Physical Properties

The galaxies are in gravitational interaction with each other. NGC 7771 is undergoing a massive star formation spurt, which may have been caused by the dwarf galaxy NGC 7770. This appears to be in the early stages of a merger with NGC 7771. The resulting tidal disturbances may have caused the apparent two-armed spiral pattern and forced a significant portion of the disk gas inward. [438] Distances range from 58 Mpc to 63 Mpc (189 to 205 million light years) [145]

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
NameRA [hms]Dec [dms]mTypeDim [']Btot [mag]HRV [km/s]PA [°]
NGC 776923 51 04.1+20 09 06S M1.6 x 1.612.84215
NGC 777023 51 22.6+20 05 54C M.8 x .714.54264
NGC 777123 51 25.0+20 06 49SB M2.4 x 1.113.0428768

Finder Chart

The NGC 7771 galaxy group is located in the constellation Pegasus. The best observation time is June to November, when it is highest at night.

Chart NGC 7771
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

References

144Catalogue of Principal Galaxies (PGC); Paturel G., Fouque P., Bottinelli L., Gouguenheim L.; Astron. Astrophys. Suppl. Ser. 80, 299 (1989); cdsarc.unistra.fr/viz-bin/cat/VII/119 (2021-02-18)
145SIMBAD astronomical database; simbad.u-strasbg.fr/simbad
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; klima-luft.de/steinicke (2021-02-17)
438«A multiwavelength study of the starburst galaxy NGC 7771» Richard I. Davies, Almudena Alonso-Herrero, Martin J. Ward; Monthly Notices of the Royal Astronomical Society, Volume 291, Issue 3, November 1997, Pages 557–568; DOI:10.1093/mnras/291.3.557
463«Catalogue of one thousand new nebulae and clusters of stars» William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1786; DOI:10.1098/rstl.1786.0027