NGC 5857

NGC 5857 is a barred spiral galaxy in the constellation of Boötes. Its velocity with respect to the cosmic microwave background for is 4,911±12 km/s, which corresponds to a Hubble distance of 236.3 ± 16.5 Mly (72.44 ± 5.07 Mpc).^[1] In addition, 20 non-redshift measurements give a distance of 228.85 ± 2.06 Mly (70.167 ± 0.633 Mpc).^[2] It was discovered by German-British astronomer William Herschel on 27 April 1788.^[3]

NGC 5857
NGC 5857 imaged by SDSS
Observation data (J2000 epoch)
Constellation	Boötes
Right ascension	15h 07m 27.2818s[1]
Declination	+19° 35′ 51.942″[1]
Redshift	0.015834[1]
Heliocentric radial velocity	4,747±2 km/s[1]
Distance	236.3 ± 16.5 Mly (72.44 ± 5.07 Mpc)[1]
Group or cluster	NGC 5859 Group (LGG 394)
Apparent magnitude (V)	13.1[1]
Characteristics
Type	SB(s)b[1]
Size	~107,700 ly (33.03 kpc) (estimated)[1]
Apparent size (V)	1.2′ × 0.6′[1]
Other designations
UGC 9724, MCG +03-39-004, PGC 53995, CGCG 106-005[1]

The SIMBAD database lists NGC 5857 as a Seyfert II Galaxy, i.e. it has a quasar-like nucleus with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable.^[4]

The galaxy pair NGC 5859 (top) and NGC 5857 (bottom) imaged by Adam Block

NGC 5859 Group

According to A. M. Garcia, NGC 5857 is a member of the NGC 5859 galaxy group (also known as LGG 394). This group has six members, including NGC 5859, UGC 9620, UGC 9622, UGC 9672, and UGC 9777.^[5]

Abraham Mahtessian mentions that NGC 5857 and NGC 5859 form a pair of galaxies and they are in gravitational interaction.^[6]

Supernovae

Two supernovae have been observed in NGC 5857:

• SN 1950H (type unknown, mag. 17.6) was discovered by Fritz Zwicky on 17 March 1950.^[7][8]
• SN 1955M (type unknown, mag. 14.5) was discovered by Fritz Zwicky on 14 May 1955.^[7][9]

See also

• List of NGC objects (5001–6000)