Candidate 1 (also known as C1 or Alpha Centauri Ab) is an unconfirmed
exoplanet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...
candidate directly imaged around
Alpha Centauri A in February 2021. If confirmed as an exoplanet, it would orbit at approximately 1.1 AU away from Alpha Centauri A with a period of about a year and would have a mass between that of
Neptune
Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 time ...
and one-half that of
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; ...
and would therefore likely be a gas giant.
The planet candidate is yet to be confirmed as an exoplanetary signal; additional observations are needed to confirm its true nature.
History
Astronomers from the Breakthrough Watch Initiative directly imaged the habitable-zone candidate using a newly developed system for mid-infrared exoplanet imaging. Previous observations from years before ruled out the possibility of it being a background star. The team presented the discovery of the exoplanet candidate in a publication in ''
Nature Communications
''Nature Communications'' is a peer-reviewed, open access, scientific journal published by Nature Portfolio since 2010. It is a multidisciplinary journal and it covers the natural sciences, including physics, chemistry, earth sciences, medicine, ...
'' titled “Imaging low-mass planets within the habitable zone of Alpha Centauri.” However, the observation arc, being only 100 hours long, is not enough to determine whether a signal is planetary in nature, and it may be zodiacal dust or an instrumental artifact.
The possible detection of the planet is extremely preliminary, and the object may not even count as a planetary candidate.
Imaging an Alpha Centauri Planet
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Physical characteristics
While little is known about the candidate planet, there are some characteristics that may be inferred based on its observations. It would have an orbital inclination of ~70° relative to Earth's point of view, consistent with the inclination of the Alpha Centauri system as a whole. Because of the detection algorithm, it would be somewhere around Neptune's mass, and would be no larger than as its mass would exceed the radial-velocity threshold of ~,
See also
* Lists of exoplanets
* List of directly imaged exoplanets
This is a list of extrasolar planets that have been directly observed, sorted by observed separations. This method works best for young planets that emit infrared light and are far from the glare of the star. Currently, this list includes both ...
* List of largest exoplanets
* List of nearest exoplanets
There are known exoplanets, or planets outside the Solar System that orbit a star, as of ; only a small fraction of these are located in the vicinity of the Solar System. Within , there are 97 exoplanets listed as confirmed by the NASA Exoplane ...
References
{{Portal bar, Astronomy, Stars, Spaceflight, Solar System
Alpha Centauri
Exoplanet candidates