How many stars have companions?

How many stars have companions?

The fraction of binary stars has implications in many fields of astronomy. Yet, we still don’t know this number, and even less how it varies with properties such as metallicity. Today’s paper sheds some light on this open question.
Image credits: Palomar Observatory/STScI/WikiSky

Dark Energy and the Future

Dark Energy and the Future

We understand cosmology by building models that we can trace back through time, but nothing about these models limits them to the past. As the universe expands, faster and faster pushed by dark energy, when does that acceleration outstrip gravity? And when do the last stars form?