Photographs by NASA/ESA
Top, a debris disk, more than 40 billion miles across, hovers around a star. Above, a debris disk encircles a star similar to our Sun.
Posted on 12/21/2004 9:32:45 AM PST by neverdem
Astronomers think they know what goes into making a planetary system, namely dust - lots of it - swirling around a newly minted star.
So it has been encouraging that astronomers have detected and even photographed dusty disks around many nearby stars, and they have inferred the presence of more than 100 planets around other stars. But until recently they had never seen dust and planets around the same stars.
This month, astronomers said they had closed the loop.
New observations by the Hubble Space Telescope and the Spitzer Space Telescope of dusty disks around nearby stars, they said, had given them a snapshot of the entire sequence by which planets coagulate out of the primordial swirl and clear out the insides of the disks, turning them into doughnuts of far-flung dust.
Using Hubble, astronomers photographed thick disks of dust around a pair of young stars that might still be in the process of forming planets. Meanwhile, the Spitzer telescope trained on 26 stars known to harbor planets detected the infrared, or heat radiation, from dust surrounding 6 of the stars.
"Spitzer really closes the loop. It shows us the planets and the dust," Dr. Alycia Weinberger, a planetary expert at the Carnegie Institution of Washington, said at a news conference at the Jet Propulsion Laboratory, the base for Spitzer's control team. Dr. Weinberger compared the new observations to seeing both a house and the bricks out of which the house had been made.
One team, led by Dr. David Ardila of Johns Hopkins University, used Hubble to photograph the disk of dust surrounding the star known as HD 107146, about 88 light-years away in the constellation Coma Berenices.
The star is some 50 million to 250 million years old, young enough so that any rocky planets there may still be forming. This is the first time that a disk has been photographed around a star similar to our Sun, he said.
Viewed nearly face-on, it resembles a reddish doughnut with a hole large enough to contain the orbits of the planets in our own solar system, Dr. Ardila said.
"This picture," he said, "provides a context in which to study the history of our own solar system."
Another team, led by Dr. John Krist of the Space Telescope Science Institute, used Hubble to photograph a disk, seen edge-on, around a reddish dwarf star known as AU Microscopii. It, too, has a cleared-out space in the middle as big as the orbit of Uranus and hints of warping due perhaps to the gravitational pull of a planet.
A similar architecture has been deduced for the disks detected by the Spitzer telescope, which is designed to see long-wavelength infrared, or heat radiation, invisible to the eye.
From the relatively low temperatures of the dust, only about 50 degrees above absolute zero, the Spitzer team, led by Dr. Charles Beichman of the Jet Propulsion Laboratory was able to conclude that the disks are all far from their stars. They are on the order of 10 times the distance of Earth from the Sun, but much thinner than the disks seen by Hubble around the younger stars.
All this fits, the astronomers said, with the idea that planets form out of thick disks of gas, gradually clearing them out. The pressure of starlight also blows dust out of the system, but the constant banging and colliding of planetoids creates new dust, which winds out in a thin outer doughnut.
"Young stars have huge reservoirs of planet-building material, while older ones have only leftover piles of rubble," Dr. Beichman said in a press release from the Jet Propulsion Laboratory. "Hubble saw the reservoirs and Spitzer, the rubble."
Our own solar system, the astronomers pointed out, has a similar disk of junk, known as the Kuiper Belt, a band of icy debris on the fringes of our own solar system, as well as dust in the inner regions that gives rise to the zodiacal light. But none of this would be visible to Spitzer or Hubble, the astronomers say.
By correlating the details of the architecture of these systems with the planets that live there, and with future observations by more sensitive spacecraft, the astronomers said they hoped to find out more about what makes planetary systems tick.
"These new disks discovered by Spitzer have the potential to be our Rosetta stone," Dr. Weinberger said.
Photographs by NASA/ESA
Top, a debris disk, more than 40 billion miles across, hovers around a star. Above, a debris disk encircles a star similar to our Sun.
Think of it, we are all made of stardust. What was that song from the sixties?
I'm clueless.
Very cool. Thanks.
ping
Great, there's planets forming under my bed.
FReepmail me if you want on or off my health and science ping list.
Here's a great link:
http://fuse.pha.jhu.edu/~wolven/astronomy.html
Links to experiments, observatories, spacecraft and journals.
Takes a lot of courage to admit that!
Optimist: "We are all made of stardust."
Pessimiet: "We are all made of nuclear waste."
God works on....
Glad to hear they got this one figured out. Maybe tomorrow they can tell me with certainty whether or not it's going to rain down my way
Hoagie Carmichael, an Indiana native. Great version by Willie Nelson.
Thanks for the link.
Loved that song!
"We are stardust
We are golden
And we’ve got to get ourselves back to the garden"
Crosby Stills Nash and Young sang the Joni Mitchell song, “Woodstock”
NASA is in such a sorry state that the U.S. is unable to fulfill its contribution to the ISS, which will never be fully realized. The Space Shuttle program, once the totem of American technological prowess, is past its prime. No longer the leaders in space exploration perhaps the American people will be content to stay on the sidelines and watch. After all they have their Social Security, Welfare, Single Parent Programs and Food Stamps.
Zodiacal light? Astronomers are such poets.
Here's a NASA photo:
Zodiacal Light
Credit & Copyright: D. Malin
Explanation: Sometimes the sky itself seems to glow. Usually, this means you are seeing a cloud reflecting sunlight or moonlight. If the glow appears as a faint band of light running across the whole sky, you are probably seeing the combined light from the billions of stars that compose our Milky Way Galaxy. But if the glow appears triangular and near the horizon, you might be seeing something called zodiacal light. Pictured above, zodiacal light is just sunlight reflected by tiny dust particles orbiting in our Solar System. Many of these particles were ejected by comets. Zodiacal light is easiest to see in September and October just before sunrise from a very dark location.
Think of it, we are all made of stardust. What was that song from the sixties?
Try 1933, "Stardust" music by Hoagy Carmichael, lyrics by Mitchell Parish, a true classic of American music, as was Hoagy.
Thanks for the pic and comment.
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