Artwork of planer Kepler 70b. Kepler 70 is a sub-dwarf star. It passed through the red giant phase, losing much of its mass, and is now in a helium-burning phase. Its radius in only 20 percent that of the Sun. Two planets have been confirmed in orbit around Kepler 70, with a possible third awaiting confirmation. The closest in, Kepler 70b, orbits at just 0.006 AU (astronomical units) from the sub-dwarf. By contrast, in our own Solar System, Mercury is nearly 70 times further from the Sun. This scene imagines Kepler 70b. It may once have been a gas giant, having lost its gaseous envelope owing to the ferocious heat of its nearby star. Now only the core of the former planet remains, little more than a ball of molten rock.