NGC 55

NGC 55, also known as the String of Pearls Galaxy,^[7] is a Magellanic type barred spiral galaxy located about 6.5 million light-years away in the constellation Sculptor. It was discovered on 7 July 1826 by Scottish astronomer James Dunlop.^[8] Along with its neighbor NGC 300, it is one of the closest galaxies to the Local Group, probably lying between the Milky Way and the Sculptor Group.^[8] It has an estimated mass of (2.0 ± 0.4) × 10¹⁰ M_☉.^[9]

NGC 55
Magellanic barred spiral galaxy NGC 55 imaged by the La Silla Observatory
Observation data (J2000 epoch)
Constellation	Sculptor[1]
Right ascension	00h 14m 53.6s[2]
Declination	−39° 11′ 47.9″[2]
Redshift	0.000437[2]
Heliocentric radial velocity	131 ± 2 km/s[2]
Distance	6.5 ± 0.65 Mly (2.00 ± 0.2 Mpc)[3][4] [a]
Apparent magnitude (V)	7.87[5][6]
Characteristics
Type	SB(s)m[2]
Mass	(2.0 ± 0.4) × 1010 M☉
Size	~68,500 ly (20.99 kpc) (estimated)[2]
Apparent size (V)	32.4′ × 5.6′[2]
Other designations
PGC 1014,[2] Caldwell 72, 2MASS J00145360-3911478, IRAS F00124-3929, ESO 293-50, MCG -07-01-013[5]

Nearby galaxies and group information

NGC 55 and the spiral galaxy NGC 300 have traditionally been identified as members of the Sculptor Group, a nearby group of galaxies in the constellation of the same name. However, recent distance measurements indicate that the two galaxies actually lie in the foreground.^[10]

It is likely that NGC 55 and NGC 300 form a gravitationally bound pair.^[4]

Visual appearance

The Webb Society Deep-Sky Observer's Handbook^[11] writes the following about NGC 55: "Nearly edge-on and appears asymmetrical with some signs of dust near the bulge, which is diffuse, broad and somewhat elongated with the south edge sharp; southeast of the bulge it is strongly curved and lined with 4 or 5 faint knots; north edge of the curve is sharp." Burnham calls it "one of the outstanding galaxies of the southern heavens", somewhat resembling a smaller version of the Large Magellanic Cloud.^[12] In September 1897, the famous New York comet hunter Lewis Swift observed the galaxy from Echo Mountain, California with a 16-inch refractor. He mistook the galaxy's faint eastern section as a new find (even though John Herschel had drawn it) and that is how it got cataloged as IC 1537.^[13]

See also

• NGC 4236
• NGC 4631
• List of NGC objects (2001–3000)

Notes

1. ^{^} average(6.9 ± 0.7,^[3] 7.5 ± 1.1^[4]) = ((6.9 + 7.5) / 2) ± ((0.7² + 1.1²)^0.5 / 2) = 7.2 ± 0.7