Science and Technology · Space Science and Astronomy

Consider the following statements regarding quadruple star systems and brown dwarfs: I. Quadruple star systems can exist in complex hierarchical configurations, consisting of multiple stellar or substellar components orbiting a common center of mass. II. Brown dwarfs are typically much smaller in radius than Jupiter, despite being substantially more massive. III. Brown dwarfs are difficult to detect directly because of their low surface temperatures and intrinsic faintness. IV. Brown dwarfs are often called 'failed stars' because they lack sufficient mass to sustain stable hydrogen fusion in their cores. Which of the statements given above are correct?