Messier 106 (also known as
NGC 4258) is an
intermediate spiral galaxy in the
constellationCanes 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. M106 contains an
active nucleus classified as a
Type 2 Seyfert, and the presence of a central
supermassive black hole has been demonstrated from
radio-wavelength observations of the rotation of a
disk of molecular gas orbiting within the inner
light-year around the black hole.
[8]NGC 4217 is a possible companion galaxy of Messier 106.
[7] A
Type II supernova was observed in M106 in May 2014.
[9]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. Water masers are useful for observing 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, thereby providing an independent anchor for the cosmic
distance ladder.
[10][11] 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 × 107
M⊙.
[12]It is one of the largest and brightest nearby galaxies, similar in size and luminosity to the
Andromeda Galaxy.
[13] The
supermassive black hole at the core has a mass of (3.9±0.1)×107
M☉.
[14]M106 has also played an important role in calibrating the
cosmic distance ladder. Before,
Cepheid variables from other galaxies could not be used to measure distances since they cover ranges of
metallicities different from the Milky Way's. M106 contains Cepheid variables similar to both the metallicities of the Milky Way and other galaxies' Cepheids. By measuring the distance of the Cepheids with metallicities similar to our galaxy, astronomers are able to recalibrate the other Cepheids with different metallicities, a key fundamental step in improving quantification of distances to other galaxies in the
universe.
[3] 
Comments