Dwingeloo 1

Dwingeloo 1 is a barred spiral galaxy of type SB ( s ) cd at a distance of about 10 million light years from our solar system. The galaxy is located in the constellation of Cassiopeia and is situated in the Galactic plane in the so-called Zone of Avoidance of the Milky Way, known for the galactic background by a large number of stars and interstellar dust to hide. The mass and size of the spiral galaxy Dwingeloo 1 are comparable to the Triangulum Galaxy.

Dwingeloo 1 has the two known satellite galaxies Dwingeloo 2 and 3 MB and is a member of the Maffei group, a group of galaxies in close proximity to our Local Group.


Dwingeloo 1 was in 1994 during the screening of the Dwingeloo Obscured Galaxy Survey ( DOGS) discovered the basis of its radio wave emissions from the investigated 21 cm emission line for signs neutral hydrogen gas in the so-called Zone of Avoidance of the Milky Way.

The galaxy was actually recorded previously in the same year in the screening of the Palomar Sky Survey, but was not recognized as a galaxy, but categorized as insignificant feature.

Dwingeloo 1 was also discovered in the same year independently of another astronomical research team who worked with the Effelsberg radio telescope.

After the discovery of the galaxy was classified as a barred spiral galaxy, determines their distance to 3 Mpc. In their dimensions as total mass and size is roughly comparable to the Triangulum Galaxy.

Got its name from the Dwingeloo Dwingeloo 1 radio telescope in the Netherlands, which was used for the DOGS screening and with which the galaxy was first discovered.

Distance and group membership

Dwingeloo 1 is a very strong area covered by the foreground Milky Way galaxy, which makes distance determination very difficult. Initial estimates were made soon after their discovery, and based on the Tully -Fisher relation, and came to 3 Mpc. Later measurements were at slightly higher rates with 3.5 to 4.0 Mpc.

In 1999, an estimate was published that claimed the distance with 5 Mpc to have measured. This was based on the infrared Tully -Fisher relation. As of 2011 is the most likely distance of Dwingeloo 1 approximated again at 3 Mpc, due to their membership of the Maffei group.

Dwingeloo 1 has two smaller satellite galaxies. The first known as Dwingeloo 2 is a dwarf irregular galaxy, while the other 3 MB is probably a spheroidal dwarf galaxy. All three galaxies are part of the group of galaxies of the Maffei group.



As a barred spiral galaxy Dwingeloo 1 has a central bar and two spiral arms clearly emerging that originate at right angle from the beam and writhe counterclockwise. The length of the arms can be up to 180 °. The disc of the galaxy is inclined with respect to the observer at an angle of 50 °.

The galaxy moves away from the Milky Way at a speed of about 256 km / s


The visible radius of Dwingeloo 1 is about 4.2 minutes of arc, which corresponds to about absolutely kpc a value of 4 at a distance of 3 Mpc. Neutral hydrogen gas can be observed up to 6 kpc, or 7.5 arcminutes beyond. The total mass up to the latter will be about 31 billion M ☉. Thus, it is a quarter of the total mass of the Milky Way.

The distribution of neutral hydrogen is typical of barred spirals is relatively flat with a minimum in the center of the galaxy or along the Balken.Die total mass of the gas in Dwingeloo 1 is about 370-450 million M ☉ abgeschätzt.Damit this galaxy belongs to the gas- poor galaxies. The total mass of molecular hydrogen is not higher than 10 % of the total neutral Wasserstoffs.Beobachtungen in the visible region of the spectrum show the 15 H II regions, which are located along the spiral arms.