SDSS found that values of Petrosian R50 over R90 below 0.3 correspond to these objects. A feature of these non-solar system objects only occur between two Lindblad resonances. These objects comprise most of the blue cloud on color–magnitude diagrams. A "traffic jam" analogy is used to explain the density wave theory of Lin and Shu that describes these objects' characteristic feature. Especially well-defined versions of these "late-type" objects are called (*) "Grand Design." Luminosity of these objects is proportional to the third power of velocity according to the Tully–Fisher relation. These objects occupy the top rung of the Hubble tuning fork, with similar "barred" objects occupying the bottom rung. For 10 point
SDSS found that values of Petrosian R50 over R90 below 0.3 correspond to these objects. A feature of these non-solar system objects only occur between two Lindblad resonances. These objects comprise most of the blue cloud on color–magnitude diagrams. A "traffic jam" analogy is used to explain the density wave theory of Lin and Shu that describes these objects' characteristic feature. Especially well-defined versions of these "late-type" objects are called (*) "Grand Design." Luminosity of these objects is proportional to the third power of velocity according to the Tully–Fisher relation. These objects occupy the top rung of the Hubble tuning fork, with similar "barred" objects occupying the bottom rung. For 10 points, name these galaxies that, like the Milky Way, are not elliptical or irregular.
SDSS found that values of Petrosian R50 over R90 below 0.3 correspond to these objects.
spiral galaxies [prompt on partial answer; accept spiral galaxy after “galaxies” is read] &lt;JL, Astro&gt;