A UCL-led research team has used artificial intelligence (AI) techniques to infer the influence and properties of dark energy more precisely from a map of dark and visible matter in the universe covering the last 7 billion years.
The study, submitted to the Monthly Notices of the Royal Astronomical Society and available on the arXiv preprint server, was carried out by the Dark Energy Survey collaboration. The researchers doubled the precision at which key characteristics of the universe, including the overall density of dark energy, could be inferred from the map.
This increased precision allows researchers to rule out models of the universe that might previously have been conceivable. READ MORE...
To us, stars may resemble cut jewels, glittering coldly against the velvet darkness of the night sky. And for some of them, that may actually be sort of true.
As a certain type of dead star cools, it gradually hardens and crystallizes. Astronomers have found one doing just that in our cosmic backyard, a white dwarf composed primarily of carbon and metallic oxygen just 104 light-years away, whose temperature-mass profile suggests that the center of the star is transforming into a dense, hard, 'cosmic diamond' made up of crystallized carbon and oxygen.
The discovery is detailed in a paper accepted into the Monthly Notices of the Royal Astronomical Society and available on preprint website arXiv.
"In this work we present the discovery of a new Sirius-like quadruple system at 32 parsecs distance, composed of a crystallizing white dwarf companion to the previously known triple HD 190412," write an international team of astronomers led by Alexander Venner of the University of Southern Queensland in Australia.
"By virtue of its association with these main sequence companions, this is the first crystallizing white dwarf whose total age can be externally constrained, a fact that we make use of by attempting to empirically measure a cooling delay caused by core crystallization in the white dwarf."
All things in the Universe must change. Every star that hangs in the firmament, shining brightly with the light generated by atomic fusion, will one day run out of fuel for their fires and evolve into something new.
For the vast majority of stars – those below about eight times the mass of the Sun, and including the Sun – that something is a white dwarf star.
When the fuel runs out, the star's outer material is shucked into the surrounding space, and the remaining core, no longer supported by the outward pressure supplied by fusion, will collapse down into an ultradense object, around the size of Earth (or the Moon!), but packing in as much mass as 1.4 Suns. READ MORE...
