Atom & Cosmos

Glint of the galaxy’s dark matter halo
A faint glow suffusing the sky might arise from dying particles of dark matter, the as-yet-unspotted stuff making up most of the universe’s mass. All galaxies, including the Milky Way, are thought to sit in giant clouds of dark matter. A balloon-borne experiment recently detected a trace of extra energy in every direction it looked. That faint glow may come from the annihilation of particles called WIMPs throughout the galaxy’s halo, an Italian and Spanish team suggests online August 2 on arXiv.org. The particle masses match previous predictions based on ground and space experiments. —Camille Carlisle

Stardust is enough
Stars deep inside galaxy clusters are made of the same stuff as stars everywhere else, argue astronomers from Michigan State University in East Lansing. Galaxies buried in the depths of clusters have been assumed to make their stars by funneling hot material in from outside themselves. But the dust content is pretty high in the gas these galaxies are using to make stars, and dust comes from the outer layers of aging stars. The gas and dust shed by stars inside the galaxy should be enough to explain most of the new star formation that is observed, the astronomers report in an upcoming Astrophysical Journal Letters. —Camille Carlisle

Slow down before big bang
Some would-be supernovas need to simmer down before they can explode. White dwarfs, the cores of dead sunlike stars, go kablooey when they suck too much material off a companion star. This hose of material can spin up the white dwarf, and the faster spin increases the amount of mass the stellar cinder can grab before it explodes. Even once the dwarf is heavy enough to explode, its spinning insides need to slow down first, Dutch and American astronomers report in the Sept. 1 Astrophysical Journal Letters. Changes in pre-explosion conditions that happen while the dwarf is spinning up and down might explain some off-color members of this generally dependable group of supernovas but shouldn’t undermine their utility as standard candles to measure cosmic distances. —Camille Carlisle