<Li> Sd (SBd)--very loosely wound, fragmentary arms; most of the luminosity is in the arms and not the bulge </Li> <P> Although strictly part of the de Vaucouleurs system of classification, the Sd class is often included in the Hubble sequence . The basic spiral types can be extended to enable finer distinctions of appearance . For example, spiral galaxies whose appearance is intermediate between two of the above classes are often identified by appending two lower - case letters to the main galaxy type (for example, Sbc for a galaxy that is intermediate between an Sb and an Sc). </P> <P> Our own Milky Way is generally classed as SBb, making it a barred spiral with well - defined arms . However, this classification is somewhat uncertain since we can only infer how our galaxy would appear to an outside observer . </P> <P> Examples of regular spiral galaxies: M31 (Andromeda Galaxy), M74, M81, M104 (Sombrero Galaxy), M51a (Whirlpool Galaxy), NGC 300, NGC 772 . </P>

In the hubble scheme for classifying galaxies what type of galaxy is the milky way