Relative size of brown dwarf stars (IMAGE) University of Sydney Caption An image displaying the relative size of a typical brown dwarf star. In the instance of the star in this study, the brown dwarf is smaller than Jupiter (between 0.65 and 0.95 its radius) but is more massive, somewhere between four and 44 times the mass of Jupiter. Credit NASA/JPL Usage Restrictions No restrictions. License Public Domain Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.