The closest distance at which humans could live next to a star without being destroyed by solar radiation or other harmful effects would depend on several factors, including the size, temperature, and activity of the star.
In general, stars emit a wide range of radiation, including ultraviolet (UV) radiation, X-rays, and gamma rays. These forms of radiation can be harmful to life as we know it. Additionally, the gravitational pull of a star can have significant effects on nearby objects, potentially causing disruptions or even tidal forces that could be destructive.
Considering these factors, it is generally accepted that for a star similar to our Sun, the habitable zone or the region around the star where conditions could support liquid water on the surface of a planet is the most likely place for life as we know it to exist. In our solar system, Earth is located within the habitable zone.
The exact boundaries of the habitable zone vary depending on the star's characteristics, such as its luminosity and size, as well as the atmosphere of the planet in question. For a star like the Sun, the habitable zone is estimated to be within a range of distances of roughly 0.95 AU to 1.37 AU (1 AU is the average distance between the Earth and the Sun, approximately 93 million miles or 150 million kilometers).
To put this into perspective, the closest star to our solar system, Proxima Centauri, is located about 4.24 light-years away. If we consider a hypothetical scenario where Proxima Centauri had a habitable zone similar to our Sun's, the minimum distance for humans to live near that star without being adversely affected by radiation or gravitational forces would still be several million miles.
It's important to note that living so close to a star would still present significant challenges. Intense heat, solar flares, and other stellar activities could pose risks to human survival and infrastructure. Therefore, while it's interesting to consider the possibility of living closer to a star, it remains a highly challenging and hypothetical scenario.