Properties
As a barred spiral galaxy Dwingeloo 1 has a central bar and two distinct spiral arms beginning from the ends of the bar at nearly right angle and wound counterclockwise. The length of the arms is up to 180°. The disk of the galaxy is inclined with respect to the observer with the inclination angle being 50°. The galaxy recedes from the Milky Way at the speed of about 256 km/s.
The visible radius of Dwingeloo 1 is approximately 4.2', which at the distance of 3 Mpc corresponds to about 4 kpc. The neutral hydrogen is detected as far as 6 kpc (7.5') from the center. The total mass of the galaxy within the latter radius is estimated at 31 billion Solar masses. The total mass of the galaxy is about 1/4 that of the Milky Way, out to the measured distance of 6 kpc.
The distribution of the neutral hydrogen in Dwingeloo 1 is typical one for barred spiral galaxies—it is rather flat with a minimum in the center or along the bar. The total mass of the neutral hydrogen is estimated at 370–450 million Solar masses. Dwingeloo 1 is a molecular gas-poor galaxy. The total mass of the molecular hydrogen does not exceed 10% of that of neutral hydrogen. Optical observations detected around 15 H II regions situated mainly along the spiral arms.
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