Nebula. Collapse. Protostar. Main Sequence. Red Giant. Planetary Nebula. White Dwarf. This is the cycle of life for a star like our Sun. By observing stars across the galaxy, we see snapshots of different points in a star’s life cycle. It’s the same with people; If you went for a walk in a city and observed people for a day, you would see every single stage of a person’s life: Infant, child, adolescent, youth, adult, middle aged, senior. How would you put them in order if you knew nothing about them? With people you might go up and ask them, but with stars we can...
Massive stars and low-mass stars live different lives. They are born in different environments, fuse different elements during the course of their lives, release different amounts of radiation across the electromagnetic spectrum, die in different ways, and enrich interstellar space with different metals. We see stars at all stages of life in the galaxy, and their study allows us to piece together how stars form, and how the rarest ones are different. The image above shows two distinct clouds, both about 5,000 light years away in the constellation Cygnus, along the Galactic plane. The smaller bubble on the left, literally...
Some of the most gorgeous, ghostly, and variable objects in the universe are planetary nebulae. They are all formed in a similar process, as a low-mass star (like our Sun) sheds it’s outer layers of gas and dust, heating them to a glow as they disperse over hundreds of millions of years. A few Billion years from now, the Sun will undergo the same major state change. When this happens, perhaps other species in the far future will gaze upon it and marvel at its beauty. One of the difficulties in studying a planetary nebula is measuring it’s distance from...
Globular Clusters are tightly packed collections of hundreds of thousands of very old stars, spherically distributed around the Milky Way Galaxy. They undergo little change, have nearly no gas, and have a stellar density way higher than the rest of the Galaxy. The first one discovered, in 1665, is messier 22, one of the most well studied, easily visible, and interesting globular clusters. Based on observations, this globular cluster contains at least two black holes. It is also one of only three globular clusters ever found to host a planetary nebula, a gaseous shell emitted by a dying star with...
