A better tool for more accurate planet hunting
Anew calibration tool developed by researchers at the CarnegieInstitute is set to have a big impact in the hunt for exoplanets. Thetechnology allows astronomers to use a longer wavelength of lightwhen analyzing distant stars, making it possible to pick out falsepositives in results.
Whileit's obvious that a planet is influenced by the gravity of its parentstar, the relationship actually goes two ways, with the orbiting bodyalso exerting a small influence of the star. The effect is, as youmight expect, far more subtle, manifesting itself as a tiny shake orwobble induced as the planet tugs on the star.
Knownas the radial velocity method, astronomers have used that littleshake to pick out hundreds of exoplanets across the night sky, butit's not an entirely foolproof means of detection. In the case of certain low-massstars, looking at that wobble may well indicate the presence of a planet, but other things can also cause the phenomenon, meaning that false positives can creep into results.
Tofix the accuracy problem, the Carnegie Institute researchers decidedto switch from visible to infrared wavelengths when makingmeasurements. The wobble effect remains the same when observing innear-infrared as with visible light, but scientists can ascertainmore from the data, picking out false positives caused by phenomenasuch as sunspots. Such things look the same as a planet in visiblelight, but are distinct at infrared wavelengths.
Whileinfrared radial velocity measurements have been made before, the newcalibration tool developed by the team significantly improves things, removing technological issues that have made visiblelight readings the preferred option until now.
Theyused the updated tool to study 32 low-mass stars with the NASAInfrared Telescope Facility located at the top of Mauna Kea inHawaii. The results correlated well with existing confirmed data onthe targets, identifying several planets and binary systems.Additionally, several new planerary candidates were identified.
"Ourresults indicate that this planet-hunting tool is precise and shouldbe a part of the mix of approaches used by astronomers goingforward," said researcher Peter Gao. "It's amazing to thinkthat two decades ago we'd only just confirmed exoplanets actuallyexisted and now we're able to refine and improve those methods forfurther discoveries."
Fulldetails of the work are published online in The Astrophysical Journal.