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Hubble confirms nearest known extrasolar planet SPACE TELESCOPE SCIENCE INSTITUTE NEWS RELEASE Posted: October 9, 2006 NASA's Hubble Space Telescope, in collaboration with ground-based observatories, has provided definitive evidence for the existence of the nearest extrasolar planet to our solar system.
The Hubble observations were achieved by a team led by G. Fritz Benedict and Barbara E. McArthur of the University of Texas at Austin. The observations reveal the the planet's true mass, which the team has calculated to be 1.5 times Jupiter's mass. Hubble also found that the planet's orbit is tilted 30 degrees to our line of sight, which is the same inclination as a disk of dust and gas that also encircles Epsilon Eridani. This is a particularly exciting result because, although it has long been inferred that planets form from such disks, this is the first time that the two objects have been observed around the same star. The research team emphasized that the alignment of the planet's orbit with the dust disk provides compelling direct evidence that planets form from disks of gas and dust debris around stars. The planets in our solar system share a common alignment, evidence that they were created at the same time in the Sun's disk. But the Sun is a middle-aged star - 4.5 billion years old - and its debris disk dissipated long ago. Epsilon Eridani, however, still retains its disk because it is young, only 800 million years old. McArthur originally detected the planet in 2000 by measurements that were interpreted as a rhythmic, back-and-forth wobble in Epsilon Eridani caused by the gravitational tug of an unseen planet. Nevertheless, some astronomer wondered if in fact the turbulent motion of the young star's atmosphere was mimicking the effects of the star being nudged by a planet's gravitational pull. The Hubble observations settle any uncertainty. The Benedict-McArthur team calculated the planet's mass and its orbit by making extremely precise measurements of subtle changes in the star's location in the sky, a technique called astrometry. The slight variations are unmistakably caused by the gravitational tug of the unseen companion object. Benedict's team studied over a thousand astrometric observations from Hubble collected over three years. "You can't see the wobble induced by the planet with the naked eye," Benedict said. "But Hubble's fine guidance sensors are so precise that they can measure the wobble. We basically watched three years of a nearly seven-year-long dance of the star and its invisible partner, the planet, around their orbits. The fine guidance sensors measured a tiny change in the star's position, equivalent to the width of a quarter 750 miles away." The astronomers combined these data with other astrometric observations made at the University of Pittsburgh's Allegheny Observatory. They then added those measurements to hundreds of ground-based radial-velocity measurements made over the past 25 years at McDonald Observatory at the University of Texas, Lick Observatory at the University of California Observatories, the Canada- France-Hawaii Telescope in Hawaii, and the European Southern Observatory in Chile. This combination allowed them to accurately determine the planet's mass by deducing the tilt of its orbit. Although Hubble and other telescopes cannot image the gas giant planet now, they may be able to snap pictures of it in 2007, when its orbit is closest to Epsilon Eridani. The planet may be bright enough in reflected starlight to be imaged by Hubble, other space-based cameras, and large ground-based telescopes. The results are being presented today at the 38th Annual Division of Planetary Sciences Meeting in Pasadena, Calif. and will appear in the November issue of the Astronomical Journal. The Hubble Space Telescope is an international cooperative project between NASA and the European Space Agency. The Space Telescope Science Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington. |
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Dazzling images from Mars are revealed by scientists. The robotic rover Opportunity has reached the massive Victoria crater with its steep cliffs and layers of rock exposing the planet's geologic history. Meanwhile, the new Mars Reconnaissance Orbiter has photographed the rover and its surroundings from high above.
Loaded with a package of telescopes in its payload bay, shuttle Columbia soared into space for the first ASTRO mission in December 1990. The crew narrates this highlights film from the STS-35 mission in which the astronauts worked around the clock in two shifts to operate the observatory. The flight launched and then landed at night, and included the astronauts teaching from space.
n this news conference from NASA Headquarters, scientists announce the Hubble Space Telescope's discovery of 16 extrasolar planet candidates orbiting a variety of distant stars in the central region of our Milky Way galaxy. Five of the newly found planets represent a new extreme type of planet not found in any nearby searches.
After its safe landing to end mission STS-115, space shuttle Atlantis is towed from the Kennedy Space Center runway to hangar 1 of the Orbiter Processing Facility for post-flight deservicing and the start of preparations leading to its next mission, STS-117.
Space shuttle Atlantis glides to a smooth touchdown on Kennedy Space Center's Runway 33 at 6:21 a.m. to conclude the successful STS-115 mission that restarted construction of the space station.
The Russian Soyuz TMA-9 space capsule carrying the Expedition 14 resident crew and space tourist Anousheh Ansari safely docks to the International Space Station's Zvezda service module.
This extended duration movie follows the Soyuz rocket from the final countdown through arrival in orbit with the Expedition 14 crew. The video shows the three-stage rocket's ascent from Baikonur Cosmodrome and includes views of Mike Lopez-Alegria, Mikhail Tyurin and Anousheh Ansari from cameras inside the capsule.