NGC 7793 - SA(s)d

NGC 7793

De Vaucouleurs Atlas Type: SA(s)d

Filter: B

Telescope: CTIO 1.5-m
North up , East left
Field Dimensions: 12.1 x 9.0 arcminutes

RC3 Type: SA(s)d
RSA Type: Sd(s)IV
Surface Brightness Range Displayed: 19.0-27.0 mag per square arcsec
Absolute Blue Magnitude: -18.5
Elmegreen Spiral Arm Class: AC 2

De Vaucouleurs Atlas Description:

Considered a prototype of stage Sd (Shapley and Paraskevopoulos 1940), NGC 7793 is one of the brighter members of the Sculptor Group . The spiral structure is ill-defined and largely flocculent in nature. The B-V color index map shows considerable star formation and dust in the inner regions. The color index map also reveals the blue color of the small nuclear source. This object is a ``nuclear star cluster" (NSC), a phenomenon found in 75% of spiral galaxies later in type than Sc (Boker et al. 2002). The mean effective radius of such clusters is 3.5 pc, comparable to typical Galactic globular clusters , but the NSCs are more luminous than a typical globular by 4 mag (Boker et al. 2003).