De Vaucouleurs Atlas Type: SA(r)bc
Telescope: CTIO 1.5-m
North left , East down
Field Dimensions: 6.1 x 6.8 arcminutes
RC3 Type: SA(rs)bc pec
RSA Type: Sc(r)I
Surface Brightness Range Displayed: 19.5-26.5 mag per square arcsec
Absolute Blue Magnitude: -21.2
Elmegreen Spiral Arm Class: AC 9
De Vaucouleurs Atlas Description:
This spectacular ``grand design " spiral is one of the best examples of its type in the sky. The two-armed spiral pattern is very well-defined, with each arm winding at least 360o. The way the arms are lined by bright stellar associations inspired a ``beads on a string" description of spiral structure at one time (C. C. Lin). The inner ring is an exceptional feature, perfectly closed but slightly miscentered. An independent, diffuse two-armed spiral pattern lies inside the inner ring . This pattern winds in the same sense as the two main outer arms. All of the spiral arms and the inner ring are patchy in the B-band but in the I-band these features are all very much smoother. There is no bar visible in the I-band image, thus NGC 5364 is a genuine nonbarred ringed galaxy.
The B-I color index map reveals the distribution of dust and star formation in the galaxy. The inner ring is visible in this map as a narrow zone of recent star formation. Interestingly, the map does not reveal strong dust lanes on the inner edges of the main arms, where they are often seen in other galaxies thought to have a strong spiral density wave (e.g., NGC 1566 ). Instead, the obvious dust lanes lie well inside major interarm areas.
The Sbc classification of NGC 5364 is based on the general patchiness and openness of the arms, and on the relatively significant bulge.