Spring Break
Groups take first photos of extrasolar planets
Issue date: 11/20/08
The problem for years was that there was too much light: Light emitted from a star would simply cover up any light emitted from a planet orbiting it. The problem is similar to finding a burning match in a forest fire. However, recent advances in imaging and optics have allowed scientists to effectively remove the bright light emitted by stars, leaving behind only the light reflected by the planets.
An international team, led by Paul Kalas of the University of California, Berkeley, used the Hubble Space Telescope to take a visible-light image of the region around the star Fomalhaut. The star has a massive ring of dust surrounding it that appears to have a cleanly groomed inner edge.
It was an ideal candidate to look at, because it fits the accretion model, a theory that proposes that planets form when large masses orbiting around stars begin gathering up nearby debris. As the debris accumulates and condenses, primordial planets increase in size.
The team estimates that the planet, named Fomalhaut b, is 18 billion kilometers away from its star and is about three times the mass of Jupiter. Fomalhaut b completes an orbit in about 870 years and may have a ring system similar to one Jupiter had in its earlier history.
Bruce Macintosh, an astrophysicist from Lawrence Livermore National Laboratory in California, led a separate team that imaged a planetary system orbiting a star named HR 8799, located in the Pegasus constellation. Using the Gemini North telescope and W.M. Keck Observatory on the island of Mauna Kea in Hawaii, the astronomers obtained infrared images of the three member planetary system.
The solar system is similar to our own. The three planets, which are estimated to be between seven and 13 times the mass of Jupiter, are as far away from their parent star as the outer planets in our solar system. The smaller planets are also closer to their star than the larger planets, an observation predicted by accretion theory.
Astronomers estimate the planets to be only about 200 million years old, young compared to the Earth, which is over four billion years old. These planets provide astronomers with an opportunity to study the early stages of planet formation and solar system evolution.
However, there is some dispute about whether or not these images are actually of extrasolar planets. Earlier claims have been made, and some have yet to be confirmed. Many have turn out to be brown dwarfs, sub-stellar objects whose mass is below the necessary limit to maintain a nuclear fusion reaction.
"My understanding is that at least one of them (the one seen by Hubble) has a dust ring near the planet and that the astronomers determined that the planet must have a mass less than three times that of Jupiter or it would have disrupted the dust disk," Hopkins physics and astronomy professor Adam Riess said.
"Three times Jupiter is too small to be a brown dwarf and really is a planet. The definition usually involves being massive enough to have any kind of fusion. ?Deuterium fuses at approximately 13 times the mass of Jupiter, so this guy qualifies as a planet."
An international team, led by Paul Kalas of the University of California, Berkeley, used the Hubble Space Telescope to take a visible-light image of the region around the star Fomalhaut. The star has a massive ring of dust surrounding it that appears to have a cleanly groomed inner edge.
It was an ideal candidate to look at, because it fits the accretion model, a theory that proposes that planets form when large masses orbiting around stars begin gathering up nearby debris. As the debris accumulates and condenses, primordial planets increase in size.
The team estimates that the planet, named Fomalhaut b, is 18 billion kilometers away from its star and is about three times the mass of Jupiter. Fomalhaut b completes an orbit in about 870 years and may have a ring system similar to one Jupiter had in its earlier history.
Bruce Macintosh, an astrophysicist from Lawrence Livermore National Laboratory in California, led a separate team that imaged a planetary system orbiting a star named HR 8799, located in the Pegasus constellation. Using the Gemini North telescope and W.M. Keck Observatory on the island of Mauna Kea in Hawaii, the astronomers obtained infrared images of the three member planetary system.
The solar system is similar to our own. The three planets, which are estimated to be between seven and 13 times the mass of Jupiter, are as far away from their parent star as the outer planets in our solar system. The smaller planets are also closer to their star than the larger planets, an observation predicted by accretion theory.
Astronomers estimate the planets to be only about 200 million years old, young compared to the Earth, which is over four billion years old. These planets provide astronomers with an opportunity to study the early stages of planet formation and solar system evolution.
However, there is some dispute about whether or not these images are actually of extrasolar planets. Earlier claims have been made, and some have yet to be confirmed. Many have turn out to be brown dwarfs, sub-stellar objects whose mass is below the necessary limit to maintain a nuclear fusion reaction.
"My understanding is that at least one of them (the one seen by Hubble) has a dust ring near the planet and that the astronomers determined that the planet must have a mass less than three times that of Jupiter or it would have disrupted the dust disk," Hopkins physics and astronomy professor Adam Riess said.
"Three times Jupiter is too small to be a brown dwarf and really is a planet. The definition usually involves being massive enough to have any kind of fusion. ?Deuterium fuses at approximately 13 times the mass of Jupiter, so this guy qualifies as a planet."
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