Candidate 1

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Candidate 1
Candidate1 Discovery.png
The discovery image of Candidate 1, taken by the NEAR instrument at ESO's Very Large Telescope in 2021.
Discovery[1]
Discovered byK. Wagner, et al.
Discovery date2021
Detection method
Direct imaging
Designations
Alternative names
Alpha Centauri Ab, Rigil Kentaurus b, C1
Orbital characteristics
Semi-major axis
1.1 AU
Orbital period (sidereal)
~360 d
Inclination~70°
StarAlpha Centauri A
Physical characteristics
Mean radius
3.3-7 REarth
Mass~20-50 MEarth

Candidate 1 (also known as C1 or Alpha Centauri Ab) is an exoplanet 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 and one-half that of Saturn and would therefore likely be a gas giant.[1] The planet candidate is yet to be confirmed as an exoplanetary signal; additional observations are needed to confirm its nature.

History[]

Astronomers from the Breakthrough Watch Initiative directly imaged the habitable-zone candidate using a newly developed system for mid-infrared exoplanet imaging.[2] 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 titled “Imaging low-mass planets within the habitable zone of Alpha Centauri.”[3] 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 "detection" of planet is extremely preliminary, object may be not conforming even for the planetary candidate status.[4]

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 point-of-view 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 7 REarth as its mass would exceed the radial-velocity threshold of ~50 MEarth,[5] but a radius lower than 3.3 REarth would not render the signature given in the paper. Due to this large mass, it is highly unlikely to be rocky and is likely a Neptune-sized planet. Follow-up observations will be needed to determine whether it is planetary, cloud of dust, or simply an artifact due to its short observation arc.

See also[]

References[]

  1. ^ a b Wagner, K.; Boehle, A.; Pathak, P.; Kasper, M.; Arsenault, R.; Jakob, G.; Käufl, U.; Leveratto, S.; Maire, A.-L.; Pantin, E.; Siebenmorgen, R. (2021-02-10). "Imaging low-mass planets within the habitable zone of α Centauri". Nature Communications. 12 (1): 922. doi:10.1038/s41467-021-21176-6. ISSN 2041-1723.
  2. ^ "Astronomers' hopes raised by glimpse of possible new planet". the Guardian. 2021-02-10. Retrieved 2021-02-12.
  3. ^ Gough, Evan (2021-02-11). "Possible Super-Earth in the Habitable Zone at Alpha Centauri". Universe Today. Retrieved 2021-02-12.
  4. ^ Imaging an Alpha Centauri Planet
  5. ^ Zhao, L.; Fischer, D.; Brewer, J.; Giguere, M.; Rojas-Ayala, B. (January 2018). "Planet Detectability in the Alpha Centauri System". Astronomical Journal. 155 (1): 12. arXiv:1711.06320. Bibcode:2018AJ....155...24Z. doi:10.3847/1538-3881/aa9bea. S2CID 118994786. Retrieved 29 December 2017.
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