Proxima Centauri, is less luminous than the sun

That’s why we can see them. There are lots of less luminous stars in the sky that we can’t see.  Our closest star, Proxima Centauri, is less luminous than the sun. Without telescopes we wouldn’t know it was there.  The next nearest are the binary pair, Alpha Centauri A and B. A is about 50% more luminous than the sun, while B is 50% less luminous. We can’t distinguish them with the naked eye because they’re so close. They appear in our night sky like a single bright star, the fourth brightest.