Friday, February 22, 2013
Worlds: The Kepler Planet Candidates
Worlds: The Kepler Planet Candidates from Alex Parker on Vimeo.
This animation shows the 2299 high-quality (multiple transits), non-circumbinary transiting planet candidates found by NASA's Kepler mission so far. These candidates were detected around 1770 unique stars, but are animated in orbit around a single star. They are drawn to scale with accurate radii (in r / r* ), orbital periods, and orbital distances (in d / r*). They range in size from 1/3 to 84 times the radius of Earth. Colors represent an estimate of equilibrium temperature, ranging from 4,586 C at the hottest to -110 C at the coldest - red indicates warmest, and blue / indigo indicates coldest candidates.
Watching in full screen + HD is recommended, so you can see even the smallest planets! Animation details below the break.
The animation is rendered with a time-step of 30 minutes, equal to the long-cadence time sample of the Kepler observatory. Three white rings illustrate the average orbital distances of Mercury, Venus, and Earth on the same scale.
When the system is animated edge-on, it is clear that there is no time during which the sample of stars the Kepler spacecraft is observing does not contain a planet transiting a star. In fact, on average there are dozens of transits occurring amongst the Kepler sample at any given instant.
The Kepler observatory has detected a multitude of planet candidates orbiting distant stars. The current list contains 2321 planet candidates, though some of these have already been flagged as likely false-positives or contamination from binary stars. This animation does not contain circumbinary planets or planet candidates where only a single transit has been observed, which is why "only" 2299 are shown.
I have illustrated the planet candidates as if they orbit a single star. Using a transit lightcurve, a planet's distance from a star and its radius are both measured in terms of the host stars' radius, and those relationships are preserved here. This means that for two planets of equal size, if one orbits a larger star it will be drawn smaller here. Similarly, because the orbital distances scale with the host stars' sizes, some planets orbit faster than others at a given distance from the star in the animation (when in reality, planets on circular orbits around a given star always orbit at the same speed at a given distance). These faster-moving planets are orbiting denser stars.
A fraction of these candidates will likely be ruled out as false positives as time goes on, while the remainder stand to be confirmed as real planets by follow-up analysis. For example, the large orange object in a very close-in orbit was shown to be a background eclipsing binary blend.
At the beginning of the animation, the grid of rectangles that briefly appears represents the focal plane array of CCD detectors onboard Kepler.
The current list of planet candidates can be found here
Music: 2 Ghosts I, Nine Inch Nails. Animation rendered with Python / PyLab.
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