M 94 

M 94 or Messier 94 (also known as NGC 4736, “Cat's Eye Galaxy”) is a spiral galaxy in the mid-northern constellation Canes Venatici. It was discovered by Pierre Méchain in 1781, and catalogued by Charles Messier two days later. Although some references describe M94 as a barred spiral galaxy, the "bar" structure appears to be more oval-shaped. Interestingly, and quite uniquely, the galaxy has two ring structures.

M94 has an inner ring with a diameter of  about 5,400 light-years (1,700 pc) and an outer ring with a diameter of about 45,000 light-years (14,000 pc). The inner ring is the site of strong star formation activity and is sometimes referred to as a starburst ring. This star formation is fueled by gas driven dynamically into the ring by the inner oval-shaped bar-like structure.

Galaxy M 94, 1, 2 & 3 April 2025, Noordwijk, William Optics 110 mm APO FLT f/7, ASI1600mm pro, 600D, L(UV-IR cut) filter, L (6840 s), R (3600 s), G (3600 s), B (3600 s), PixInsight V1.9

The outer ring of M94 is not a closed stellar ring, as historically attributed in the literature, but a complex structure of spiral arms when viewed in mid-IR and UV. It was found that the outer disk of this galaxy is active. It contains approximately 23% of the galaxy's total stellar mass and contributes about 10% of the galaxy's new stars. In fact, the star formation rate of the outer disk is approximately two times greater than the inner disk because it is more efficient per unit of stellar mass. There are several possible external events that could have led to the origin of M94's outer disk including the accretion of a satellite galaxy or the gravitational interaction with a nearby star system. 

Distance measurements give a distance estimate of 16.0 ± 1.3 million light-years (4.9 ± 0.4 Mpc). M94 is one of the brightest galaxies within the M94 Group, a group of galaxies that contains between 16 and 24 galaxies. This group is one of many that lie within the Virgo Supercluster (i.e. the Local Supercluster).