NGC 4194
Interacting galaxy pair in the constellation of Ursa Major
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NGC 4194, the Medusa merger, is a galaxy merger in the constellation Ursa Major about 128 million light-years (39.1 Mpc) away.[4] It was discovered on April 2, 1791 by German-British astronomer William Herschel.[8] Due to its disturbed appearance, it is object 160 in Halton Arp's 1966 Atlas of Peculiar Galaxies.[7]
| NGC 4194 | |
|---|---|
 | |
| Observation data (J2000 epoch) | |
| Constellation | Ursa Major |
| Right ascension | 12h 14m 09.64s[1] |
| Declination | +54° 31′ 34.60″[1] |
| Redshift | 0.008433[2] |
| Heliocentric radial velocity | 2,511±12 km/s[3] |
| Distance | 128 Mly (39.1 Mpc)[4] |
| Apparent magnitude (V) | 13.30[5] |
| Apparent magnitude (B) | 13.79[5] |
| Characteristics | |
| Type | Imeger[2] |
| Apparent size (V) | 0.14′ × 0.13′[6] |
| Notable features | Interacting, starburst |
| Other designations | |
| Medusa galaxy merger, NGC 4194, Arp 160, UGC 7241, Mrk 201, PGC 39068[7] | |
The morphological classification of NGC 4194 is Imeger,[2] indicating an irregular form. This galaxy consists of a brighter central region spanning an angular size 9″ across, with an accompanying system of loops and arcs. Additional material is thinly spread out to a radius of 75″ from the central region.[9] There is a tidal tail and regions undergoing high levels of star formation, making this a starburst galaxy. It is a source for strong infrared and radio emission.[10][11] These features indicate NGC 4194 is a late-stage galaxy merger.[12] A region of extreme star formation 500 ly (150 pc) across exists in the center of the Eye of Medusa, the central gas-rich region.[13]
Within 1.2 kpc (3.9 kly) of the dynamic center of NGC 4194, star formation is occurring at a rate of 8 M☉·yr−1. The star forming regions in this volume range from 5 to 9 million years in age, with the youngest occurring in areas of the highest star formation rate.[14] As of 2014, no galactic nucleus has been detected based on radio emissions, nor have the respective nuclei of the merger galaxies.[15] However, X-ray emission from a black hole in the tidal tail was detected by Chandra in 2009.[16]
