Determining the exact amount of helium in our galaxy, the Milky Way, is a complex task that involves various factors and uncertainties. However, astronomers have estimated the abundance of helium relative to other elements in the Milky Way based on observations and theoretical models.
Helium is primarily produced through nuclear fusion processes in stars, particularly during stellar nucleosynthesis. As stars evolve and eventually exhaust their nuclear fuel, they release helium and other elements into the surrounding space through stellar winds and supernova explosions. This enriched material then mixes with the interstellar medium, which is the vast expanse of gas and dust between stars.
Based on observations and models, it is generally accepted that helium constitutes around 23-25% of the total elemental mass in the Milky Way. This value is often expressed in terms of the helium-to-hydrogen ratio, with the estimated ratio being approximately 0.25. In other words, for every four hydrogen atoms, there is roughly one helium atom in the galaxy.
It's important to note that this estimation is subject to some uncertainties due to the challenges in measuring and modeling the interstellar medium accurately. Additionally, the helium abundance can vary in different regions of the galaxy, and it may be influenced by various astrophysical processes such as stellar evolution, star formation rates, and the chemical enrichment history of the Milky Way.
Overall, while we have estimates for the relative abundance of helium in the Milky Way, determining the exact amount of helium in terms of its mass or volume is a complex task that requires ongoing observations and research in astrophysics.