Amazing stuff!
New Planets Astound Astronomers in Speed and Distance
By DENNIS OVERBYE
Published: October 5, 2006
In the quest for other worlds beyond the solar system, astronomers keep turning up planetary systems with curiouser and curiouser traits. Yesterday, astronomers who use the Hubble Space Telescope announced that they had done it again, this time locating the fastest moving and most distant ever found.
Among a batch of new planets found by training the Hubble telescope on a small patch of sky far across the galaxy in Sagittarius are as many as five that orbit their home stars in less than a day.
One planet orbits its star, a so-called dwarf slightly smaller than the Sun, in only 10 hours, “the likes of which we had never seen before,” Kailash Sahu of the Space Telescope Science Institute, leader of the team that did the work, said, calling the results “a big surprise.”
By comparison, Mercury, swiftest in the our solar system, races around the Sun once every 88 days.
The new planets, all roughly the size of Jupiter, orbit so near their stars that they are heated to 3,000 degrees Fahrenheit, said Dr. Sahu, who noted that if their home stars were any bigger, the planets would simply evaporate.
The astronomers reported their results at a news conference at NASA headquarters in Washington, and their findings will be published in the journal Nature today.
The results, astronomers said, confirm that planets occur across the galaxy with the same frequency that they do in the neighborhood around the Sun.
“We’ve learned now that planets are everywhere,” said Alan P. Boss, a theorist at the Carnegie Institution of Washington, who was not part of the team.
“We’re beginning to be able to calculate how many Earths there are, how many planets are habitable, if not inhabited,” Dr. Boss added.
More than 200 planets have now been found around other stars.
In all, the project — known as Sagittarius Window Eclipsing Extrasolar Planet Search, or Sweeps — found 16 possible planets by monitoring the light from 180,000 stars over seven days, looking for the periodic dimming caused by the passage of a planet. The astronomers have calculated by statistical methods that at least seven of the bodies are actually planets.
So far, two have been confirmed as planets by measuring the wobbles in the starlight caused by the passing masses, using the giant eight-meter Very Large Telescope at the European Southern Observatory on Cerro Paranal, in Chile.
Dr. Sahu said those findings gave him confidence that at least a large fraction of the 16, if not all, are really planets.
Dr. Boss noted that astronomers now had found in the Milky Way all the types of planets that are in our solar system: gas giants like Jupiter, ice giants like Neptune and rocky “super-Earths” orbiting other stars. “Everything we were looking for,” he said, “just not in the arrangement we were looking for.”
As potential planets are found in increasing numbers, Dr. Boss said, the odds increase that planets and planetary systems like Earth’s would be found.
Mario Livio, an astronomer at the Space Telescope Science Institute and a member of Dr. Sahu’s team, said, “There are literally billions of planets in our galaxy.”
nytimes.com |
