Carbon Content in Dwarf Stars

About 90 percent of all stars, those with an initial mass up to about eight times the mass of the Sun, end their life as white dwarfs, very dense and compact stellar remnants destined to cool forever, becoming less and less bright. Before this happens, in the last breaths of life, these stars leave a last important legacy, scattering their ashes in the surrounding space in the magnificent form of planetary nebulae. These ashes, diffused in the cosmos through the so-called "stellar winds", are enriched with many chemical elements, including carbon, created in the deepest layers of the star during the last phases before death. Carbon is essential for life on Earth, every carbon atom in the universe was created by the stars through the fusion of three helium nuclei. The origin of carbon in our galaxy, the Milky Way, is still the subject of lively debate among astrophysicists. Some studies are in favor of low-mass stars that ejected their outer mantles into space by means of stellar winds and became white dwarfs, others place the main site of carbon synthesis in the winds of massive stars that eventually exploded as supernovae.

A recent study, published on Nature Astronomy, take more evidence that white dwarfs can give answers on the origin of carbon in the Milky Way.

In the image: NGC 7789. Credit: Guillaume Seigneuret. Nasa.