NGC 4561

NGC 4561 is a barred spiral galaxy in the constellation Coma Berenices. It was discovered by German-British astronomer William Herschel on April 13, 1784.^[8] This galaxy is located at a distance of 82 ± 14 million light-years (25.2 ± 4.3 Mpc) from the Milky Way,^[4] and is a member of the Virgo Cluster of galaxies.^[5] It is 13th magnitude with an angular size of 1.5′.^[9]

NGC 4561
Hubble Space Telescope image of NGC 4561
Observation data (J2000 epoch)
Constellation	Coma Berenices
Right ascension	12h 36m 08.137s[1]
Declination	+19° 19′ 21.32″[1]
Redshift	0.00454±0.00020[2]
Heliocentric radial velocity	1,410 km/s[3]
Distance	82 ± 14 Mly (25.2 ± 4.3 Mpc)[4]
Group or cluster	Virgo Cluster[5]
Apparent magnitude (B)	12.70[3]
Characteristics
Type	SB(rs)dm,[6] Sc(dSc)[3]
Number of stars	1.23×109 M☉[5]
Apparent size (V)	0.727′ × 0.581′[1] (NIR)
Other designations
2MASX J12360813+1919213, NGC 4561, IC 3569, UGC 7768, PGC 42020[7]

The morphological classification of NGC 4561 in the De Vaucouleurs system is SB(rs)dm,^[6] indicating a barred spiral galaxy (SB) with a transitional inner ring structure (rs), loosely wound spiral arms (d), and an irregular appearance with no bulge component (m). The galactic plane is inclined at an angle of 28° to the plane of the sky, with the major axis aligned along a position angle of 60°.^[5] It has a star formation rate of 0.23 M_☉·yr⁻¹. The net stellar mass of the galaxy is 1.23×10⁹ M_☉.^[5]

A nuclear X-ray source was detected in NGC 4561 by Chandra, and was determined to be an active galactic nucleus based on XMM-Newton observations. It has a small supermassive black hole at the source, with a mass of at least 2×10⁴ M_☉.^[10]