Mega-Earth discovered around a mini sun
Scientists have spotted a new planet three times the size of Earth about 3,000 light-years away from our solar system. Given its size, astronomers believe the planet is made of rock and ice, unlike the Jupiter-size gas giants that comprise most of the exoplanets found so far. Monikered MOA-2007-BLG-192L b per NASA’s cataloguing guide, the planet tightly orbits a star that is 6 to 10 percent the mass of our own sun, making this the tiniest star known to have a planet. The finding, set for publication in the Astrophysical Journal, serves as a boon to hunters of both extrasolar worlds and extraterrestrial life by vastly increasing the number of stars that could potentially sport Earth-like planets. The host star and its planetary companion turned up when researchers observed microlensing, a phenomenon of general relativity that Albert Einstein predicted in which light is warped by the gravity of an object passing between Earth and a more distant star. The middle object bends light emanating from the star to an expected degree. If there are variances in this, then some other object or matter may be changing the way the light is warped, enabling astronomers to glean the presence of a planetary body as well as its mass and size. A team of scientists led by David Bennett of the University of Notre Dame presented the discovery at a meeting of the American Astronomical Society in St. Louis this week.
Disarming news for the Milky Way
Could our long-held views of the Milky Way be wrong? Since the 1950s, conventional wisdom has held that four star-filled spiral arms pinwheel about the center of our home galaxy. But new research reveals that the galaxy wields two—not four—major limbs. Researchers led by Robert Benjamin of the University of Wisconsin– Whitewater, used NASA’s Spitzer Space Telescope to paint this new portrait of our galactic residence. Spitzer views the universe in dust-penetrating infrared light, providing scientists clearer views of the Milky Way's hub from which the spiral arms sprout. Other recent surveys have revealed the presence of a large bar of stars across our galaxy's middle, and the large spirals, called the Scutum-Centaurus and Perseus Arms, seem to match up with the ends of this bar. These major arms contain the most stars, both young and old, whereas other, subsidiary arms possess darker dust pockets and star-forming regions. So where is Earth in this sprawling cosmos-politan city? Our planet lies in a partial arm known as the Orion Arm or Spur, about halfway out from the center and halfway way in from the city limits—essentially a Milky Way suburb. The results of the study were announced at the 212th meeting of the American Astronomical Society in St. Louis this week.