NGC 7331 Galaxy Group

NGC 7331 & Stephan's Quintet
NGC 7331 & Stephan's Quintet: Galaxies in Pegasus; 11" RASA; QHY268M (SW); ToupTek MONO 2600MP (RGB); 56 min; Amden; © 2023-08-19 Peter Stüssi
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 [32]

Galaxy NGC 7331

This galaxy was discovered by William Herschel on 5 September 1785 using his 18.7 inch reflector. He cataloged it as I 53 and noted: «Very bright, considerably large, much extended, much brighter in the middle, resolvable.» [463]

Given distances for NGC 7331 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]

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Designation NGC 7331
Type Gx (Sbc)
Right Ascension (J2000.0) 22h 37m 05.1s
Declination (J2000.0) +34° 25' 13"
Diameter 10.2 × 4.2 arcmin
Photographic (blue) magnitude 10.4 mag
Visual magnitude 9.5 mag
Surface brightness 13.3 mag·arcmin-2
Position Angle 171°
Redshift (z) 0.002722
Distance derived from z 11.50 Mpc
Metric Distance 13.940 Mpc
Identification, Remarks WH I 53; h 2172; GC 4815; UGC 12113; MCG 6-49-45; CGCG 514-68

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. [145]

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Name RA Dec Type bMag vMag B-V SB Dim PA z D(z) MD Dreyer Description Identification, Remarks
NGC 7335 22 37 19.5 +34 26 54 Gx (S0-a) 14.4 13.3 1.1 13.0 1.2 × 0.6 151 0.021065 88.98 vF, vS (B of Ld R) WH III 166; h 2174; GC 4823; UGC 12116; MCG 6-49-47; CGCG 514-69; NPM1G +34.0449
NGC 7336 22 37 21.9 +34 28 56 Gx (S) 15.3 14.5 0.8 13.1 0.8 × 0.4 139 0.029354 123.9 eF, vS (C) GC 4816; MCG 6-49-49; NPM1G +34.0450
NGC 7337 22 37 26.6 +34 22 26 Gx (SBab) 15.2 14.4 0.8 14.0 1 × 0.8 177 0.021952 92.72 eF, S, stellar (E) GC 4817; UGC 12120; MCG 6-49-50; CGCG 514-71
NGC 7340 22 37 44.1 +34 24 38 Gx (E?) 14.7 13.7 1.0 13.0 0.9 × 0.6 162 0.021348 90.17 vF, vS, (D of Ld R) GC 4818; MCG 6-49-52; CGCG 514-75; NPM1G +34.0452

Finder Chart

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

Finder Chart NGC 7331 Galaxy Group
NGC 7331 Galaxy Group in constellation Pegasus. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [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. — 12.5" Ninja-Dobson, F:4.5 / TV-Radian 8mm, 181x, 0.33, 2005, Eduard von Bergen

Objects Within a Radius of 15°

References