The Physics Of The Universe

Fomalhaut b

Fomalhaut b, also known as Dagon, is an exoplanet candidate located approximately 25 light-years away from Earth in the constellation Piscis Austrinus. It is thought to orbit the bright A-type star Fomalhaut, which is one of the most prominent stars in the night sky.


Fomalhaut b was first announced as an exoplanet in 2008 after being directly imaged by the Hubble Space Telescope's Advanced Camera for Surveys. The discovery marked a significant milestone, as Fomalhaut b was one of the first exoplanets to be directly imaged. Subsequent observations raised questions about its planetary status, as the object appeared to be fading in brightness, and its orbit seemed unusual.

In 2012, new observations suggested that Fomalhaut b might not be a planet, but rather a dust cloud resulting from a collision between two large asteroid-like bodies. In 2020, further analysis of archival Hubble images provided more evidence that Fomalhaut b might not be a planet, as its motion and brightness appeared inconsistent with a planetary interpretation.

Fomalhaut b's discovery and subsequent studies have brought attention to the challenges and complexities of directly imaging exoplanets. Its initial detection was a significant achievement, as it demonstrated the potential of the direct imaging technique for studying exoplanetary systems. The method involves detecting the light emitted or reflected by a planet, which is a difficult task because of the overwhelming brightness of the host star compared to the planet.

The uncertainties surrounding Fomalhaut b's nature have led to further research into the Fomalhaut system, including its prominent debris disk. Fomalhaut's debris disk is an extensive ring of dust and small particles that orbits the star. The presence of such a disk is indicative of a young planetary system still in the process of formation. Observations have shown that the debris disk has a sharp inner edge and a well-defined outer boundary, which may be shaped by gravitational interactions with planets in the system.


Kennedy, G. M., & Wyatt, M. C. (2011). The Brightest Debris Disk: Fomalhaut. The Astrophysical Journal Letters, 734(1), L18.

Kalas, P., Graham, J. R., Chiang, E., Fitzgerald, M. P., Clampin, M., Kite, E. S., ... & Stapelfeldt, K. (2008). Optical Images of an Exosolar Planet 25 Light-Years from Earth. Science, 322(5906), 1345-1348.

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