Messier 106 - Spiral Galaxy
Messier 106 is a barred spiral of the Hubble Type "SAB" in the constellation Canes Venatici (CVn) and is around 24 million light-years away from Earth.
It was discovered in July 1781 by P. Méchain. With a brightness of 8.3mag, it can be seen even with modern binoculars and is best observed in spring when
it is high in the sky.
With a true diameter of 125,000 light-years, Messier 106 is similar in size and mass to the Andromeda galaxy, which in turn is slightly larger than our own
Milky Way. The spiral arms have a bluish color and contain many HII regions in which many hot and young stars are currently being formed. This suggests
that the galaxy is undergoing a starburst phase.
In the center there is an active galactic nucleus of "Seyfert 2" type, which is also known as a radio source. It is fed by a supermassive black hole (SMBH)
with a mass of 39 million solar masses, which is surrounded by a very massive accretion disk with a diameter of 2 light-years and a mass of around 40
million solar masses. Two jets also emanate from there.
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Messier 106 offers a great view in my 20" f/3.2 Dobsonian. Especially at higher magnifications of 210...270x, the many fine details can be clearly seen.
The spiral arms are not particularly difficult with averted vision. The arm running to the north (top) is easier than the southern one and shows significantly
more structures. At 270x, some of the bright HII regions can be seen as small, diffuse patches - 5 of them in a row, plus another star-forming region at the
very end of the arm and a somewhat larger brightening towards the center. A very bright HII region with a stellar core can also be seen at the end of the
southern (lower) arm.
The core region is also very interesting. First of all, the very bright center is remarkable in comparison, which is also dominated by an almost stellar nucleus.
This is joined by an elongated, also very bright region, which is cut off very sharply by a dark dust band to the southwest. The contrasts are really impressive
at high magnification. Another dust filament is located to the south of the central area and can also be seen well with averted vision.
