Learning Through Uncertainty: Alpha Centauri’s Exoplanet Candidate
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Recent headlines have highlighted a new planet in our closest star system neighbor, Alpha Centauri. But how confident are scientists that it’s an exoplanet? Only time and more observations, like with NASA’s James Webb Space Telescope, will help lower the level of uncertainty.
Read the press release: NASA's Webb Finds New Evidence for Planet Around Closest Solar Twin
Read the press release: NASA's Webb Finds New Evidence for Planet Around Closest Solar Twin
Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with NASA’s Universe of Learning partners: Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and NASA Jet Propulsion Laboratory.
- Visualization of an exoplanet in host star’s glare: NASA’s Goddard Space Flight Center Conceptual Image Lab
- Image of the Very Large Telescope: ESO/Y. Beletsky
- Portion of star system Alpha Centauri as imaged by the Very Large Telescope: K. Wagner
- Visualization of star system Alpha Centauri: ESO/L. Calcada/Nick Risinger
- Portion of star system Alpha Centauri as imaged by the James Webb Space Telescope: NASA/California Institute of Technology/STScI
- Close-up images of a portion of star system Alpha Centauri as imaged by the James Webb Space Telescope: NASA/California Institute of Technology/STScI
- Artist’s concept of an exoplanet and host star: NASA/Caltech
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We move above the surface of the Earth.
Text: Where could life exist?
Is there anything out there?
Are we alone?
Title: Learning Through Uncertainty: Alpha Centauri's Exoplanet Candidate.
The universe contains exciting events and fascinating objects--
--like exoplanets, distant worlds beyond our solar system, which are difficult to find and study.
One example that shows the difficulties in identifying exoplanets is the closest star system to us, Alpha Centauri.
In 2019, the ground-based Very Large Telescope blocked some of the starlight from the system and directly imaged something new.
Was this mysterious thing a newly discovered exoplanet orbiting the closest Sun-like star to Earth? A background star or galaxy? Or was it noise from the detector?
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Because Alpha Centauri has two Sun-like stars close to each other, separating out real objects from noise is particularly challenging.
Some kinds of noise are like stray glints of light.
Scientists used a special instrument on NASA's James Webb Space Telescope to block light from the object's host star, offering another look at the scene.
After some careful computer analysis, astronomers noted Webb saw something too.
Over the course of multiple observations, Webb rolled to rotate its field of view and shift the pattern of light.
If it appeared in the same spot despite the changing fields of view, then it would build confidence in its exoplanet candidacy.
Conversely, if the source was inconsistent in its position, either it was part of the light pattern or the planet moved.
By the third round of observations, the object was missing from the telescope's field of view, ruling out that it was a background star or galaxy.
If this was an exoplanet, maybe it moved too close to its host star to be seen.
Since the data is still inconclusive, more time and observations are key to building confidence that this object is an exoplanet.
Webb will be able to provide the needed follow-up to help scientists solve this current mystery.
With each additional observation, scientists will be able to build a stronger body of evidence to help clarify the nature of our closest star system neighbor.
