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The First Stars in the Universe

Exceptionally massive and bright, the earliest stars changed the course of cosmic history

By Richard B. Larson and Volker Bromm

The Discovery of Brown Dwarfs

Less massive than stars but more massive than planets, brown dwarfs were long assumed to be rare. New sky surveys, however, show that the objects may be as common as stars

By Gibor Basri

The Stellar Dynamo

Sunspot cycles--on other stars--are helping astronomers study the sun's variations and the ways they might affect Earth

By Dmitry Sokoloff, Elizabeth Nesme-Ribes and Sallie L. Baliunas

The Fury of Solar Storms

Shock waves from the sun can trigger severe turbulence in the space around earth, endangering satellites and astronauts in orbit. A novel spacecraft is showing how space storms develop

By James L. Burch

When Stars Collide

When two stars smash into each other, it can be a very pretty sight (as long as you're not too close by). These occurrences were once considered impossible, but they have turned out to be common in certain galactic neighborhoods

By Michael Shara

Supersoft X-Ray Stars and Supernovae

Several years ago astronomers came across a new type of starthat spews out unusually low energy x-rays. These so-called supersoft sources are now thought to be white dwarf stars that cannibalize their stellar companions and then, in many cases, explode

By Edward P. J. van den Heuvel, Peter Kahabka and Saul A. Rappaport


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