A group of researchers from the University of California, Los Angeles, has detected elements in the atmosphere of the white dwarf star GD 362 that are very similar to the makeup of the Earth and moon - and very different from other white dwarf stars. According to their report, the star was contaminated by an asteroid that flew too close to the star and was broken up by gravitational forces before being consumed.
The astronomers, whose research was funded by NASA, believe that the asteroid was swallowed up by the star fairly recently - within the past million years. The findings suggest that the same process that formed smaller planets like Earth in our own solar system can also take place around other stars, thus increasing the chances of eventually finding an Earth-like planet.
August 14, 2007
Astronomers from Penn State University recently got a glimpse of our solar system's future when they discovered a massive planet circling a bloated, dying red giant star.
Only 10 solar systems have been found so far orbiting red giant stars - dying stars that balloon to many times their original size as they sputter out of fuel. These planets can be hard to find because they usually take a long time to circle around their host stars - in the case of the newly discovered planet, 360 days. These long orbital times mean that astronomers need to spend a long time observing a star in order to see the wobbles in a star's position that indicate the existence of a planet.
The new planet is 300 light years from Earth, making it one of the most distant red-giant solar systems yet discovered.
The new findings are intriguing to astronomers because they offer clues about the future of our solar system. As our sun ages over the next few billion years, it will begin to swell up and expand outward, making temperatures on Earth too hot for life and possibly even swallowing our planet whole.
On the flip side, the bulging sun might melt the ice on places like Jupiter's moon Europa, creating large oceans and perhaps allowing life to form. Scientists hope that the continued study of red giant stars will allow them to understand how the habitable zone around a star - the area where living things can survive - expands as the star gets larger.
Led by Alex Wolszczan, who in 1992 discovered the first pulsar planets, the Penn State team used the Hobby-Eberly telescope in Texas, one of the world's most powerful. The research was funded in part by NASA's Jet Propulsion Laboratory.
Astronomers find companion orbiting brown dwarf candidate
July 30, 2007
Astronomers at the Max-Planck Institute for Astronomy Heidelberg have discovered what appears to be the smallest companion yet discovered orbiting close to a low-mass star.
ChaHa8 b, as the object has been named, is around 16 to 20 times the mass of Jupiter. Its host star is very young, around 3 million years old, and is only .085 the mass of our sun. Scientists believe the star may be a brown dwarf - a failed star that is not large enough to sustain nuclear reactions at its core. The newfound companion is located about 1 AU from the star, which is the distance between the Earth and the sun in our solar system.
Source: "16-20 Jupiter mass RV companion orbiting the brown dwarf candidate ChaHa8," V. Joergens and A. Mueller, 2007, ApJ
Survey suggests super-Jupiters stay close to home
July 26, 2007
A new survey of planets orbiting other stars suggests that gas giants the size of Jupiter or larger rarely exist in the outer reaches of solar systems.
Using telescopes in Arizona and Chile, astronomers looked at 54 relatively young stars close to our own, searching for gas planets orbiting more than 5 AU from their stars. One AU is the distance from the sun to the Earth, about 93 million miles. In our solar system, the planet Jupiter is just over 5 AU from the sun.
The study, which lasted for three years, did not detect a single large planet at that distance. While a majority of the exoplanets that have been discovered are gas giants, they all tend to orbit very closely to their host stars. The new findings will help theorists develop a more complete picture of how planetary systems form.
Source: University of Arizona press release
