Projecting human capability and knowledge into the far future, provided we learn to manage our own planet, it seems possible that humans might learn how to modify stars in ways suited to their future needs. Why might one modify stars? I can think of a variety of reasons. Stars are the powerhouses of the cosmos—not only are they sources of light and heat and high energy particles, they also anchor solar systems, serve as magnetic field generators, and continually replenish the interstellar medium. I like to think of stars as plants in a garden. Different kinds of stars do somewhat different jobs, but together they form a kind of ecology, albeit on a scale we are not used to thinking about.
Indeed, some stars are better suited to supporting human life than others. Stars generally come in only a limited number of forms. These forms are determined by the mass of the star. Smaller stars are cooler, and, indeed, can only support a kind of fusion burning called proton-proton fusion, essentially the direct combination of hydrogen atoms to form helium. This process is relatively quiet and stable, and generates little movement of the gases, so the energy in the center of the star simply radiates upwards until it breaks free of the surface. Larger stars burn more hotly, and, indeed, a different form of fusion becomes possible in these stars, called the CNO cycle for the constituent elements in the burning process—carbon, nitrogen and oxygen. The CNO fusion process is both hot and turbulent, so much so that gasses move around a lot, and in these stars the movement of the gases constitutes the primary means of getting the energy generated in the middle of the star to the surface. Our star, Sol, is on the cooler end of the range. Stars across the whole range are labeled by a series of letters. From hotter to cooler, these are O, B, F, G, K, M, extended to include R, N, and S for stars with unusual compositions. Sol is a G-type star. There are a variety of mnemonics to help remember these—traditionally, the one proposed by the scientist who developed the system, Russell, is used : “Oh Be A Fine Girl(Guy), Kiss Me, Right Now Sweetheart”. Although for our purposes, perhaps a gardening metaphor might serve us better. Something like : “Onion, Beets And Fennel Garnish Kale and Mushrooms” with spices added : “Rosemary, Nutmeg, and Sage”.
So one thing that might be done to stars is to modify their masses to bring them into the right range for supporting human life. This is actually trickier to do than it might sound. You can’t simply add mass to a star’s surface layers to get the desired result—the star will likely blow off those extra layers as a heavier than normal stellar wind. Alternatively, to circumvent that problem, one might want to ‘seed’ star formation regions (also called ‘nurseries’, another tip of the hat towards gardening) in such a way that they create more G-type stars than they normally would.
Some stars pulsate at fixed frequencies based on their composition and mass as well. These variable stars can be used as natural clocks—indeed astronomers use a type of variable star as what are called “standard candles”, since their luminosity is directly correlated with their pulsing frequency. As a result, one can infer the distance of the star by observing its periodicity and then matching this to its apparent luminosity—the further away the star, the fainter it will appear. It is therefore possible that one might want to adjust the periodicity of a variable star, if one needed to use its clock-like properties for particular tasks.
Another feature of stellar nurseries are regions of space called Bok Globules. These are clouds of gas that are in the process of collapsing inwards to form new stars. As the gas density increases, it reaches a point at which the gas cloud becomes opaque in the optical part of the spectrum, although these globules continue to emit strongly in the infrared, a sign of their internal heat. Bok Globules could be likened to pockets of compost around a new seedling, where the compost is being used to nurture the plant and help it establish itself and grow.
In Plenum: The First Book of Deo, my upcoming science-fiction novel to be published by our own imprimatur, Untimely Books, the far-future religious community called the Kinship of the Suffering God is responsible for adjusting the frequency of variable stars inside the Plenum Nebula, and seeding the star formation regions of the nebula to produce more stars, particularly “Fennel” and “Kale” “Garnishes”, or F, G and K stars. Like religious communities of old, these devotees are tending their garden, both to enhance their own lives as well as to serve the wider community. Hence the imaginary future presented in Plenum explores the connectedness between human and cosmos in unusual ways, and, hopefully, carries us along with it out into the larger reaches of space and time, at a moment in history when we feel excessively bound to one time and place. Come join us on the journey!