51 Pegasi b

51 Pegasi b, officially named Dimidium /dɪˈmɪdiəm/, and formerly unofficially dubbed Bellerophon /bɛˈlɛrəfɒn/, is an extrasolar planet approximately 50 light-years (15 parsecs) away in the constellation of Pegasus. It was the first exoplanet to be discovered orbiting a main-sequence star, the Sun-like 51 Pegasi, and marked a breakthrough in astronomical research. It is the prototype for a class of planets called hot Jupiters.
In 2017, traces of water were discovered in the planet's atmosphere. In 2019, the Nobel Prize in Physics was awarded in part for the discovery of 51 Pegasi b.
== Claims of direct detection of visible light ==
The first ever direct detection of the visible light spectrum reflected from an exoplanet has been made by an international team of astronomers on 51 Pegasi b. The astronomers studied light from 51 Pegasi b using the High Accuracy Radial velocity Planet Searcher (HARPS) instrument at the European Southern Observatory's La Silla Observatory in Chile. This detection allowed the inference of a mass of 0.46 Jupiter masses. The optical detection could not be replicated in 2020, implying the planet has an albedo below 0.15. Measurements in 2021 have marginally detected a polarized reflected light signal, which, while they cannot place limits on the albedo without assumptions made about the scattering mechanisms, could suggest a high albedo.
== See also ==
* PSR B1257+12 B
* PZ Telescopii b
* HD 209458 b
Category:Exoplanets
Category:Pegasus constellation