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Exoplanet: n. a planet that orbits a star outside the solar system. |
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[Image Type (image dimensions) - image size]
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| This artist's concept shows the newly discovered Neptune-sized extrasolar planet circling the star Gliese 436. Gliese 436 is a type of low-mass star called an M dwarf, about four-tenths the size of our Sun. It appears reddish because it is cooler than a typical Sun-like star. The new planet is only the second to be found orbiting an M dwarf star, and is one of the smallest extrasolar planets detected to date. It circles Gliese 436 every 2.6 days at a small fraction of the distance between the Sun and Earth, or 4.1 million kilometers (2.6 million miles).
In this depiction, the planet appears gaseous like Jupiter, with a cloudy atmosphere. In reality, astronomers do not know if this planet is gaseous, or rocky, like Earth and Mars. The temperature of the planet is estimated to be around 370 Celsius (698 Fahrenheit), though - if locked in place like our Moon - its dark side might experience temperatures of 200 Celsius (392 Fahrenheit) or colder.
The planet was discovered using data from the W.M. Keck Observatory in Mauna Kea, Hawaii.
Image credit: NASA |
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| This graph illustrates the 2.8-day orbit of the newfound Neptune-sized extrasolar planet circling the star 55 Cancri. Astronomers can determine the orbit of an extrasolar planet by measuring the wobble it produces in a parent star.
In this case, the task was more difficult because 55 Cancri is home to three other larger Jupiter-sized planets whose tugs mask that of the smaller planet. To solve the problem, astronomers modeled the orbit of the outer planet using data from the Hobby-Eberly Telescope at McDonald Observatory in West Texas; the Lick Observatory in Northern California; and NASA's Hubble Space Telescope. Holding this orbit as a constant allowed the orbits of the three planets - including the Neptune-sized one -- to be detected.
In this graph, the directional velocity of the 55 Cancri is plotted over time to reveal the new planet's speedy orbit. Dots represent actual data points. Error bars have been removed to show more clearly the planet's sinusoidal orbit.
Image credit: University of Texas |
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[Image Type (image dimensions) - image size]
JPG (720x540) ~33KB
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| This graph illustrates the 2.8-day orbit of the newfound Neptune-sized extrasolar planet circling the star 55 Cancri. Astronomers can determine the orbit of an extrasolar planet by measuring the wobble it produces in a parent star.
In this case, the task was more difficult because 55 Cancri is home to three other larger Jupiter-sized planets whose tugs mask that of the smaller planet. To solve the problem, astronomers modeled the orbit of the outer planet using data from the Hobby-Eberly Telescope at McDonald Observatory in West Texas; the Lick Observatory in Northern California; and NASA's Hubble Space Telescope. Holding this orbit as a constant allowed the orbits of the three planets - including the Neptune-sized one -- to be detected.
In this graph, the directional velocity of the 55 Cancri is plotted over time to reveal the new planet's speedy orbit. Dots represent actual data points.
Image credit: University of Texas |
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[Image Type (image dimensions) - image size]
JPG (720x540) ~71KB
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| This graph illustrates the 2.6-day orbit of the newfound Neptune-sized extrasolar planet circling the small star Gliese 436. Gliese 436 is a type of low-mass star called an M dwarf, about four-tenths the size of our Sun. Astronomers can determine the orbit of an extrasolar planet by measuring the wobble it produces in a parent star. In this graph, the directional velocity of the star is plotted over time to reveal the new planet's speedy orbit. Dots represent actual data points. Error bars have been removed to show more clearly the planet's orbit.
In the past, finding planets the size of Neptune or smaller has proved difficult because they exert less of a tug on their parent stars than the majority of Jupiter-sized planets found so far. In this case, the parent star is smaller and more susceptible to wobbling, allowing for the detection of the new planet.
Image credit: Carnegie Institute of Washington/Univ. of Calif., Berkeley |
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[Image Type (image dimensions) - image size]
JPG (720x540) ~77KB
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| This graph illustrates the 2.6-day orbit of the newfound Neptune-sized extrasolar planet circling the small star Gliese 436. Gliese 436 is a type of low-mass star called an M dwarf, about four-tenths the size of our Sun. Astronomers can determine the orbit of an extrasolar planet by measuring the wobble it produces in a parent star. In this graph, the directional velocity of the star is plotted over time to reveal the new planet's speedy orbit. Dots represent actual data points.
In the past, finding planets the size of Neptune or smaller has proved difficult because they exert less of a tug on their parent stars than the majority of Jupiter-sized planets found so far. In this case, the parent star is smaller and more susceptible to wobbling, allowing for the detection of the new planet.
Image credit: Carnegie Institute of Washington/Univ. of Calif., Berkeley |
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[Movie Type (resolution) - movie size]
QuickTime (low) ~717KB |
QuickTime (high) ~12.9MB |
RealPlayer ~1.3MB
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| This animation illustrates how astronomers find planets beyond our solar system. When a planet circles a star, its gravitational tug forces the star to wobble back and forth. This, in turn causes the star's light to shift in frequency in the same way that the whistle on a passing train changes pitch.
This "Doppler" shift can be detected by breaking starlight apart into its component colors, or wavelengths, and looking for specific chemical "fingerprints" (black lines in rainbow at top). As the star wobbles toward Earth, these fingerprints will shift to blue wavelengths, and conversely to red wavelengths as the star recedes. By measuring how much the light shifts, astronomers can determine an extrasolar planet's approximate mass and length of orbit.
Image credit: NASA/JPL |
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[Image Type (image dimensions) - image size]
JPG (640x480) ~68KB |
JPG (1500x1125) ~224KB |
JPG (4000x3000) ~920KB |
TIF (4000x3000) ~4.2MB
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| This artist's concept shows the newfound Neptune-sized planet - one of the smallest extrasolar planets detected to date - circling the star 55 Cancri. The planet joins three others in orbit around 55 Cancri to form the first known four-planet system. It is the innermost of the bunch, whipping around the star every 2.8 days at just a fraction of the distance between the Sun and Earth, or 5.6 million kilometers (3.5 million miles).
In this illustration, the new planet is depicted as having a rocky composition, like Earth or Mars. In reality, astronomers do not know if the planet is rocky, or gaseous like Jupiter. Being so close to its parent star, the planet's temperature is at least a scorching 1500 Celsius (2700 Fahrenheit).
The star 55 Cancri is about 5 billion years old, a bit lighter in weight than the Sun, and is located 41 light-years away in the constellation Cancer.
Data from the Hobby-Eberly Telescope at McDonald Observatory in West Texas, the Lick Observatory in Northern California and NASA's Hubble Space Telescope were used to find the new planet using the radial velocity technique.
Image credit: NASA |
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[Movie Type (resolution) - movie size]
QuickTime ~1.3 MB |
QuickTime (high) ~22.6MB |
RealPlayer ~2.2MB
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| This animation shows the planetary system around the star 55 Cancri, beginning with its outermost planet and zooming in toward the star. With the recent discovery of an inner Neptune-sized planet, 55 Cancri has become the first star outside of our Sun known to support four planets.
The new planet whips around the star every 2.8 days at just a fraction of the distance between the Sun and Earth, or 5.6 million kilometers (3.5 million miles). The others orbit every 14.6, 44 and 4,520 days, respectively. The outermost of these is still the only Jupiter-sized planet known to reside as a far away from its parent star as our own Jupiter.
The star 55 Cancri is about 5 billion years old, a bit lighter in weight than the Sun, and is located 41 light-years away in the constellation Cancer.
Data from the Hobby-Eberly Telescope at McDonald Observatory in West Texas, the Lick Observatory in Northern California and NASA's Hubble Space Telescope were used to find the new planet using the radial velocity technique.
Image credit: NASA/JPL |
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