What ionized the universe?

The sparsely distributed hot gas that exists in the space between galaxies, the intergalactic medium, is ionized. The question is, how? Astronomers know that once the early universe expanded and cooled enough, hydrogen (its ...

Discovering a brown dwarf binary star with microlensing

Brown dwarfs are stars less massive than the sun and unable to burn hydrogen. They comprise (at least in mass) a bridge between planets and stars, and astronomers think that they form and evolve in ways different from either ...

Exiled planet linked to stellar flyby three million years ago

Some of the peculiar aspects of our solar system—an enveloping cloud of comets, dwarf planets in weird orbits and, if it truly exists, a possible Planet Nine far from the sun—have been linked to the close approach of ...

Stellar wind of old stars reveals existence of a partner

Red giants are old stars that eject gaseous material and solid particles through a stellar wind. Some red giants appeared to lose an exceptionally large amount of mass this way. However, new observations reveal that this ...

ESA plans mission to smallest asteroid ever visited

ESA's planet-defending Hera mission will set a new record in space. The asteroid investigator will not only be the first spacecraft to explore a binary asteroid system – the Didymos pair – but the smaller of these two ...

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