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Photo captures three planets by distant sun
Nov. 13, 2008
World Science staff
The technology for photographing planets in distant solar systems is making strides, astronomers say, with new images including one that shows three
worlds around a young star. Above, a direct image of
the star HR 8799. Below, the image after computer processing, which
reduces the starlight to a bunch of speckles and allows three
presumed planets to appear as faint red dots around the star at about 2:00, 5:00 and 10:00
o'clock. The images were taken in infrared light with the Keck telescope,
and the bottom image covers the same area as shown in the box in the top
image. (Courtesy National Research Council Canada) Send us a comment
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Astrophysicist Christian Marois and colleagues said they
found the planets—which appeared as tiny dots by the star HR 8799—using the Keck and Gemini North telescopes on
Mauna Kea in Hawaii.
Before now, astronomers had reported photographing just one planet of a star other than our sun. Other detections of such objects had been done through studying their gravitational effects rather than through imaging, which is difficult because the starlight tends to overwhelm any light from the planets.
Members of Marois’ group said they developed an advanced computer processing method that helped distinguish the planets from the starlight. Their findings appear in the Nov. 13 issue of
Science Express, the advance online edition of the research journal
Science.
HR 8799 is just visible to the unaided eye and lies about 130 light-years from Earth in the direction of the constellation Pegasus, in the northern sky. A light-year is the distance light travels in a year.
These planets, about 60 million years old, are young enough that they are still glowing from heat left over from their formation, said the researchers, led by Marois, of the National Research Council of Canada Herzberg Institute of Astrophysics in Victoria, British Columbia.
The worlds seem to be around seven, ten, and ten times the weight of Jupiter and somewhat wider, they added. But these estimates are rough, the group noted, because the speed of the planets’ orbit, which would yield the best measure of weight, is unknown.
“Comparison with theoretical model atmospheres confirms that all three planets possess complex atmospheres with dusty clouds partially trapping and re-radiating the escaping heat,” said Travis Barman, an astronomer at Lowell Observatory at the University of California Los Angeles, a co-author of the study.
Further studies of the light emissions from the planets will let researchers study their makeup in detail, he added.
The planets are measured to lie up to 70 times further from their
sun than the Earth does from ours.
Separately, another research team imaged a planet orbiting the star Fomalhaut, one of the brightest in the sky and just 25 light years from Earth. These are the first snapshots of a planet outside our solar system taken in visible light rather than in other forms of light not visible to human eyes, said University of California, Berkeley, astronomer Paul Kalas, co-author of a paper on the findings. That report also appears in the Nov. 13
Science Express.
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The technology for photographing planets in distant solar systems is making strides, astronomers say, with new images including one that shows three planets around a young star. Astrophysicist Christian Marois and colleagues said they used the Keck and Gemini North telescopes on Mauna Kea in Hawaii to find the three planets orbiting the star HR 8799. Before now, astronomers had reported photographing just one planet of a star other than our sun. Other detections of such objects had been done through studying their gravitational effects rather than through imaging, which is difficult because the starlight tends to overwhelm any light from the planets. Members of Marois’ group said they developed an advanced computer processing method that helped distinguish the planets from the starlight. Their findings appear in the Nov. 13 issue of Science Express, in the advance online edition of the research journal Science. HR 8799 is just visible to the unaided eye and lies about 130 light-years from Earth in the direction of the constellation Pegasus, in the northern sky. A light-year is the distance light travels in a year. These planets, about 60 million years old, are young enough that they are still glowing from heat left over from their formation, said the researchers, led by Marois, of the National Research Council of Canada Herzberg Institute of Astrophysics in Victoria, British Columbia. The worlds seems to be around seven, ten, and ten times the weight of Jupiter and somewhat wider, they added. But these estimates are rough, the group noted, because the speed of the planets’ orbit, which would yield the best measure of weight, is unknown. “Comparison with theoretical model atmospheres confirms that all three planets possess complex atmospheres with dusty clouds partially trapping and re-radiating the escaping heat,” said Travis Barman, an astronomer at Lowell Observatory at the University of California Los Angeles, a co-author of the study. Further studies of the light emissions from the planets will let researchers study their makeup in detail, he added. Separately, another research team imaged a planet orbiting the star Fomalhaut, one of the brightest in the sky and just 25 light years from Earth. These are the first snapshots of a planet outside our solar system taken in visible light rather than in other forms of light not visible to human eyes, said University of California, Berkeley, astronomer Paul Kalas, co-author of a paper on the findings. That report also appears in the Nov. 13 Science Express.