November 22 News Items

Oddball White Dwarfs Embody New Category of Star (Source: Reuters)
Eight unusual examples of a burned-out celestial object known as a white dwarf detected in our Milky Way galaxy represent a previously unknown category of stars, astronomers said. White dwarfs mark the end point in stellar evolution for all but the most massive of stars in the universe, with about 97 percent of stars, including our sun, destined to finish their existence this way, according to astronomers. White dwarfs result from the collapse of star cores in dying stars whose nuclear fusion has ceased. They usually have a mass about that of the sun, but are only a bit larger than Earth because they have blown off their outer layers, leaving behind only a small, dim and extremely dense core.

University of Arizona astrophysicist Patrick Dufour said previously known white dwarfs have fallen into two categories: those with a hydrogen-rich atmosphere and those with a helium-rich atmosphere. But Dufour and three other scientists, writing in the journal Nature, described eight white dwarfs that break the mold by possessing carbon atmospheres.

Study Sheds New Light on Early Formation of Earth and Mars (Source: NASA)
A team of scientists from NASA's Johnson Space Center (JSC) and the Lunar and Planetary Institute (LPI), both in Houston, and the University of California, Davis (UCD) has found that terrestrial planets such as the Earth and Mars may have remained molten in their early histories for tens of millions of years. The findings indicate that the two planets cooled slower than scientists thought and a mechanism to keep the planet interiors warm is required.

Have We Sealed the Universe's Fate by Looking At It? (Source: New Scientist)
Have we hastened the demise of the universe by looking at it? That’s the startling question posed by a pair of physicists, who suggest that we may have accidentally nudged the universe closer to its death by observing dark energy, which is thought to be speeding up cosmic expansion. By making this observation in 1998 we may have caused the universe to revert to a state similar to early in its history, when it was more likely to end. The researchers came to their conclusion by calculating how the energy state of our universe might have evolved. Visit http://www.eurekalert.org/pub_releases/2007-11/ns-hws112107.php to view the article.