What is an axion? How could axions make a star, and what does that have to do with dark matter? What would these stars look like?

What is an axion? How could axions make a star, and what does that have to do with dark matter? What would these stars look like?
Are dark photons as sinister as they sound? What did the curvaton do in the early universe? And is everything really made of preons?
Are dark photons as sinister as they sound? What did the curvaton do in the early Universe? And is everything really made of preons?
How can the solar corona be hotter than the surface? What has the Parker Solar probe learned so far? What do magnetic fields have to do with all this?
Are we “in range” of any potential supernovae? Has the Earth ever been hit in the past? What about gamma-ray bursts from across the galaxy?
How do black holes get close enough to merge? What causes them to emit gravitational waves, and where do the waves come from?
How did Pluto get demoted? What makes a planet a planet anyway? Why do we now have so many different kinds of planets, and should we make things simpler?
How do gravitational lenses work? Where would a spacecraft need to be to use the Sun’s gravity as a telescope? What could we learn about exoplanets with this on weird trick?