NGC 4666

NGC 4666 is a spiral galaxy in the equatorial constellation of Virgo, located at a distance of approximately 55 megalight-years from the Milky Way.^[3] It was discovered by the German-born astronomer William Herschel on February 22, 1784. It is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster.^[6][7] John L. E. Dreyer described it as "bright, very large, much extended 45°±, pretty suddenly brighter middle".^[8] It is a member of an interacting system with NGC 4668 and a dwarf galaxy,^[9] and belongs to a small group that also includes NGC 4632,^[2] that is known as the NGC 4666 Group.^[10][11]

NGC 4666
The superwind galaxy NGC 4666
Observation data (J2000 epoch)
Constellation	Virgo
Right ascension	12h 45m 08.676s[1]
Declination	−00° 27′ 42.88″[1]
Heliocentric radial velocity	1,517 km/s[2]
Distance	54.89 ± 0.65 Mly (16.83 ± 0.20 Mpc)[3]
Apparent magnitude (V)	10.8[4]
Characteristics
Type	SABc[2]
Apparent size (V)	4′.6 × 1'.3[2]
Notable features	Starburst
Other designations
NGC 4666, IRAS F12425-0011, MCG+00-33-008, MRC 1242-001, PMN J1245-0027, UGC 7926, UZC J124508.0-002744, PGC 42975[5]

The morphological classification of this galaxy is SABc, which indicates a weak bar around the nucleus with moderately wound spiral arms. Viewed nearly edge-on, its galactic plane is inclined at an angle of 85°±2° to the line of sight from the Earth, with the major axis aligned along a position angle of 40°. There is an active galactic nucleus that shows a modest level of activity and is most likely heavily obscured by gas and dust. The central point source has been detected in the radio and X-ray bands.^[2]

This is a starburst galaxy that is noteworthy for its vigorous star formation, which creates an unusual superwind^[12] of out-flowing gas. This wind is not visible at optical wavelengths, but is prominent in X-rays, and has been observed by the ESA XMM-Newton space telescope.^[13] The estimated star formation rate is 7.3 M_☉ yr^–1, with a density of 8.9×10⁻³ M_☉ yr⁻¹ kpc⁻². Unlike in many other starburst galaxies, the star formation is spread across the disk rather than being more concentrated.^[2]

Supernovae

Three supernovae have been observed in NGC 4666:

• SN 1965H (Type IIP, mag. 14) was discovered by Enrique Chavira on 23 May 1965.^[14][15]
• ASASSN-14lp (Type Ia, mag. 14.3) was discovered by ASAS-SN on 9 December 2014; it was located 12″ from the center of the galaxy.^[16][17]
• SN 2019yvr (Type Ib, mag. 15.882) was discovered by ATLAS on 27 December 2019.^[18][19] It has a 0.005 redshift. Images of the location of the supernova before the explosion showed the progenitor star was ~19M_☉.^[20]

Enlarged view of the center of NGC 4666 by the Hubble Space Telescope