Red giants are created when a star exhausts its supply of hydrogen at its core, with the result that the inner layer contracts and the outer layers expand, forming a redder and much larger star.
This architecture also enables NASA to leverage existing capabilities and lower development costs by using liquid hydrogen and liquid oxygen for both the core and upper stages.
Dr Marcy suspects that his new discovery, which has about 45 times the mass of the Earth, is composed of a rocky core surrounded by a thick envelope of hydrogen and helium gas.