NGC 7331 Galaxy Group

Galaxie NGC 7331

NGC 7331
NGC 7331: Group of galaxies in Pegasus; 500 mm Cassegrain 5800 mm f/11.4; SBIG STL11K; 120+10+10+10 min LRGB; Bernese Highlands; © 2005 Radek Chromik

The galaxy NGC 7331 was discovered by William Herschel on September 6, 1785. Distances range from 12.8 Mpc to 16.2 Mpc (41 to 53 million light years). With a diameter of 120'000 light-years, it is about the same size, shape and mass as our Milky Way, and has a similar rate of star formation. But unlike our Milky Way, NGC 7331 is not a barred spiral, but a spiral galaxy of morphological type SAb and with a LINER-type active core. [145, 196, 205]

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
DesignationsPGC 69327: NGC 7331, UGC 12113, MCG 6-49-45, CGCG 514-68
Right Ascension (J2000.0)22h 37m 05.1s
Declination (J2000.0)+34° 25' 11"
Morphological TypeS
Dimensions10.2' x 4.2'
Visual Magnitude10.3 mag
Radial Velocity (HRV)822 km/s
Position Angle171°

Galaxies NGC 7335, 7336, 7337, 7340

The radial velocities, which are a factor of seven to ten higher, reveal that these galaxies are not companions of NGC 7331, but that they are much further away, namely 304 to 414 million light years. They just happen to be in the same line of sight. Apparent magnitudes are around 15 mag. [204]

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
NameRA [hms]Dec [dms]mTypeDim [']Btot [mag]HRV [km/s]PA [°]
NGC 733622 37 17.4+34 26 36S.4 x .316.88800
NGC 733522 37 19.2+34 26 52L1.3 x .614.46315151
NGC 733722 37 26.6+34 22 24SB1.0 x .815.46900
NGC 734022 37 44.2+34 24 37C.9 x .614.76400

Finder Chart

NGC 7331 is located in the constellation of Pegasus and is most often used as a starting point for Stephan's Quintet.

Chart NGC 7331
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

Visual Observation

320 mm aperture: NGC 7331 appears as an elongated, oval galaxy. With 9.5 mag it offers a good brightness to be found with a small and medium-sized telescope.

The four neighboring galaxies are of interest to larger amateur telescopes. NGC 7336 is the smallest of the four companion galaxies. The brightnesses are 14.7 mag for NGC 7335, 14.9 mag for NGC 7340, and the two faint companions NGC 7336 and NGC 7337 each have 15.4 mag. These galaxies are truly a test of sky transparency and a 12.5 inch telescope. [192]

12.5" Ninja-Dobson, F:4.5 / TV-Radian 8mm, 181x, 0.33
Eduard von Bergen, 2005

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
192Deep-Sky Guide; fernrohr.ch/1d_deep-sky-guide.html (2020-12-25)
196Celestial Atlas by Curtney Seligman; cseligman.com/text/atlas.htm (2020-12-28)
204Wolfram Alpha; wolframalpha.com (2020-12-29)
205Twins with differences; esahubble.org/images/potw1805a (2020-12-30)