NGC 4258
| Messier 106 | |
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M 106 and its anomalous arms. Composite of IR (red) and optical light (Image credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and R. Gendler (for the Hubble Heritage Team))
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| Observation data (J2000 epoch) | |
| Constellation | Canes Venatici |
| Right ascension | 12h 18m 57.5s |
| Declination | +47° 18′ 14″ |
| Redshift | 448 ± 3 km/s |
| Distance | 23.7 ± 1.5 Mly (7 ± 0.5 Mpc) |
| Apparent magnitude (V) | 9.1 |
| Characteristics | |
| Type | SAB(s)bc |
| Size | 135,000 ly (in diameter) |
| Apparent size (V) | 18′.6 × 7′.2 |
| Notable features | Maser galaxy, Seyfert II galaxy. |
| Other designations | |
| M 106, NGC 4258, UGC 7353, PGC 39600. | |
Messier 106 (also known as NGC 4258) is an intermediate spiral galaxy in the constellation Canes Venatici. It was discovered by Pierre Méchain in 1781. M106 is at a distance of about 22 to 25 million light-years away from Earth. It is also a Seyfert II galaxy. Due to x-rays and unusual emission lines detected, it is suspected that part of the galaxy is falling into a supermassive black hole in the center.NGC 4217 is a possible companion galaxy of Messier 106. A Type II supernova was observed in this galaxy in May 2014.
M106 has a water vapor megamaser (the equivalent of a laser operating in microwave instead of visible light and on a galactic scale) that is seen by the 22-GHz line of ortho-H2O that evidences dense and warm molecular gas. These water vapors give M106 its characteristic purple color. Water masers are useful to observe nuclear accretion disks in active galaxies. The water masers in M106 enabled the first case of a direct measurement of the distance to a galaxy and thereby providing an independent anchor for the cosmic distance ladder. M106 has a slightly warped, thin, almost edge-on Keplerian disc which is on a subparsec scale. It surrounds a central area with mass 4 × 107M⊙.
It is one of the largest and brightest nearby galaxies, similar in size and luminosity to the Andromeda Galaxy. The supermassive black hole at the core has a mass of (3.9±0.1)×107 M☉.
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