NGC 4559

NGC 4559, also known as Caldwell 36, is an intermediate spiral galaxy located in the constellation Coma Berenices. It resides approximately 35 million light-years away from Earth and is a member of the Coma I Group, a loose group of galaxies related to the Virgo Supercluster.

Characteristics:

NGC 4559 is characterized as an intermediate spiral galaxy, meaning it falls somewhere between a barred spiral and an unbarred spiral galaxy. It displays a flocculent, or patchy, spiral arm structure, rather than well-defined, grand design arms. This type of structure suggests that its spiral arms are formed through shear forces and differential rotation within the galaxy's disk, rather than being predominantly influenced by density waves.

The galaxy spans roughly 100,000 light-years in diameter, similar in size to our own Milky Way galaxy. It exhibits a relatively low surface brightness, making it somewhat challenging to observe visually, especially in light-polluted areas.

Notable Features:

NGC 4559 contains a wealth of HII regions, areas of ionized hydrogen gas that are indicative of ongoing star formation. These regions appear as bright, blue knots scattered throughout the galaxy's spiral arms, highlighting areas where young, massive stars are being born. Supernova remnants have also been detected within NGC 4559, evidence of past stellar explosions.

Observation:

For amateur astronomers, NGC 4559 is best observed with a medium-sized to large telescope under dark skies. Its large angular size means lower magnifications are often preferred to view the entire galaxy within the field of view. The galaxy's faintness and diffuse nature make it a more rewarding target for experienced observers.

Discovery:

NGC 4559 was discovered by William Herschel in 1785.