How to make another star glow?

No and I hate the devs for this

@Luckwut @Zenithspeed ok

my technique is to use the fog shader on the atmosphere, and set the scale height to a high number (like, 50) so it covers the whole surface then increase brightness/intensity as needed
it looks fairly realistic this way, but the only downside is that you visually won't be able to see any patterns on the surface though you'll still see them in the minimap

Only the central star emit light and every celestial body face the central star. But you can make the other star 'glow' by increasing the biome color intensity or emissiveness or terrain atmosphere "max color". I'd suggest you don't use the stock star template and use other player made star or make your own.