Located in the constellation Canes Venatici, NGC 4156 is a good example of a barred spiral galaxy. The bright white area is the nuclear bulge, a huge, tightly packed sphere of stars. Attached to the bar, the red area emerging from the nucleus, are two clearly defined spiral arms forming a ring structure around the galaxy. The darker areas between the arms contain stars, gas, and dust lanes.
Look carefully at the image and you will notice that the galaxy is not perfectly symmetrical: one of the spiral arms seems to trail away. The gravitational force of another galaxy, not visible here, is pulling material away from NGC 4156.
