The Physical and Chemical Properties of Circumstellar Matter

小行星9314408 许多明亮的红巨星从它们的外层喷射出大量的物质。 然后，这颗星星迅速演变成一颗白色矮星，而这颗物质在一段时间内被视为行星状星云。 现在我们知道，这颗星星和可见的星云被一个巨大的中性气体壳层所包围。 这些壳的性质和演变将通过观察它们在毫米和亚毫米波长的分子发射来研究。 这些信息将用于描述星云的形成和演化。 这些研究将大大提高我们对这一重要但鲜为人知的恒星演化阶段的理解。 ***

9314408 Huggins Many luminous red giant stars eject significant amounts of material from their outer layers. The star then evolves rapidly into a white dwarf while the matter is seen for a time as a planetary nebula. It is now known that the star and the visible nebula are surrounded by a large shell of neutral gas. The properties and evolution of these shells will be studied by observing their molecular emission at millimeter and sub-millimeter wavelengths. This information will be used to develop a description of the formation and evolution of the nebulae. These studies should substantially improve our understanding of this important but little understood phase of stellar evolution. ***