Washington: A team of planet hunters has come up with a new tool that refines exoplanet search.
New work led
by Carnegie's Jonathan Gagne, Caltech's Peter Gao, and Peter Plavchan from
Missouri State University reports on a technological upgrade for one method of
finding planets or confirming other planetary detections.
One of the
most-popular and successful techniques for finding and confirming planets is
called the radial velocity method. A planet is obviously influenced by the
gravity of the star it orbits; that's what keeps it in orbit. This technique
takes advantage of the fact that the planet's gravity also affects the star in
return.
As a result,
astronomers are able to detect the tiny wobbles the planet induces as its
gravity tugs on the star. Using this method, astronomers have detected hundreds
of exoplanets.
For certain
kinds of low-mass stars, however, there are limitations to the standard radial
velocity method, which can cause false positives -- in other words, find
something that looks like a planet, but isn't.
To address
this issue, researchers decided to use the radial velocity technique, but they
examined a different, longer wavelength of light.
"Switching
from the visible spectrum to the near-infrared, the wobble effect caused by an
orbiting planet will remain the same regardless of wavelength," Gagne
explained. "But looking in the near-infrared will allow us to reject false
positives caused by sunspots and other phenomena that will not look the same in
near-infrared as they do in visible light,"
The research
team was able to develop a better calibration tool to improve the overall
technology for near-infrared radial velocity work, which should make it a
better option going forward.
They
examined 32 low-mass stars using this technological upgrade atthe NASA Infrared
Telescope Facility atop Mauna Kea, Hawaii. Their findings confirmed several
known planets and binary systems, and also identified a few new planetary
candidates.
"Our
results indicate that this planet-hunting tool is precise and should be a part
of the mix of approaches used by astronomers going forward," Gao said.
"It's amazing to think that two decades ago we'd only just confirmed
exoplanets actually existed and now we're able to refine and improve those
methods for further discoveries."
The result
is published by The Astrophysical Journal.
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