Hydrogen-deficient star the outer layer of the star. The double degenerate scenario is a binary-star approach in which a smaller degenerate helium white dwarf and a larger carbon-oxygen white dwarf orbit each other so closely that they eventually inspiral due to gravitational wave losses. At the Roche limit, mass transfer takes place from the helium to the carbon-oxygen star. The latter undergoes helium shell burning to form a supergiant and evolve to a hydrogen-deficient star. The double degenerate scenario provides a better fit to the observational data. Hydrogen-deficient star A hydrogen-deficient star is a type of star that has little or no
Ice giant by extreme ultraviolet (EUV) radiation emitted by θ Orionis C suggests another possible mechanism for the formation of ice giants. Multiple-Jupiter-mass gas-giant protoplanets could have rapidly formed due to disk instability before having the majority of their hydrogen envelopes stripped off by intense EUV radiation from a nearby massive star. In the Carina Nebula, EUV fluxes are approximately 100 times higher than in Trapezium's Orion Nebula. Protoplanetary disks are present in both nebulae. Higher EUV fluxes make this an even more likely possibility for ice-giant formation. The stronger EUV would increase the removal of the gas envelopes from the protoplanets