M106 - Spiral Galaxy in Canes Venatici
Discovered by Pierre Méchain in 1781.
The bright Sb spiral galaxy M106 is perhaps about 21 to 25 million light years distant. It is receding at 537 km/sec.Its equatorial plane is inclined to the line of sight so many features resemble what we know from the Andromeda galaxy M31. This orientation explains partly why the dust lanes are so prominent in this galaxy. They form a spiral pattern which can be traced well into its bright central region to the core. The spiral arms end in bright blue knots. These knots are most probably young star clusters which are dominated by their very hot, brightest and most massive stars; the occurence of these hot stars indicates that these clusters cannot be very old, as such massive stars have only a short lifetime of a few million years. So the blue knots show us the regions of very recent star formation!
Since the 1950s, M106 has been known to have a much larger extent in the radio radiation than in visual light. In 1943, Carl K. Seyfert had listed this galaxy among the galaxies with emission line spectra from their nuclei, which are now called Seyfert galaxies. Nevertheless, only few modern studies of Seyfert galaxies include it, although its nucleus is classified as Seyfert 1.9, according to the NED data of this galaxy.
M106 is one of Pierre Méchain's findings, which were later appended as additional objects to Charles Messier's catalog. In case of M106, it was Helen Sawyer Hogg who added it together with M105 and M107 in 1947, but it appears reasonable to assume that already Méchain had intended to add it to a future edition. William Herschel had numbered it H V.43 when cataloging it on March 9, 1788.--------------------------------------