With its nuclear fuel exhausted, this brief, spectacular, closing phase of a sun-like star's life occurs as its outer layers are ejected and its core becomes a cooling, fading White Dwarf.
While the planetary nebula phase is thought to last for around 10, 000 years, astronomers estimate the age of the outer filamentary portions of this halo to be 50, 000 to 90, 000 years.
虽然行星状星云阶段持续约1万年,天文学家估计其外晕的丝状物质年龄在5万至9万年间。
3
It briefly introduces the source of silt at the outer waterway of Shantou Port and construction situation and regulation effect of Phase I regulation project.