WASP-50
An older G-type star spun up by a close giant planet.
WASP-50, also known as Chaophraya, is a G-type main-sequence star roughly 594 light-years from Earth in the constellation Eridanus. It is older than the Sun and has a slightly lower abundance of heavy elements, with starspot activity close to average. Despite its advanced age, the star rotates rapidly because it is being spun up by tidal forces from a giant planet in a very close orbit.
The star's designation comes from the Wide Angle Search for Planets, a collaboration of academic institutions that detect exoplanets via the transit method. In 2019, as part of the NameExoWorlds campaign celebrating the IAU's 100th anniversary, this system was assigned to Thailand. Following a national vote organized by NARIT, the star was named Chaophraya and its planet Maeping, after the Chao Phraya and Mae Ping rivers. The Thai names were proposed by Duangrat Wichiansri.
A transiting hot superjovian planet, WASP-50b (renamed Maeping in 2019), was detected in 2011. In 2022, its albedo was measured at no more than 0.44, meaning the planet reflects less than 44% of the light from its host star, which helps constrain its equilibrium temperature.
Quick Facts
- Also named
- Chaophraya
- Spectral type
- G-type main-sequence star
- Distance
- about 594 light-years
- Constellation
- Eridanus
- Age
- older than the Sun
- Metallicity
- slightly depleted in heavy elements compared to the Sun
Facts from the source article.
Lore & Background
WASP-50 was discovered by the Wide Angle Search for Planets (WASP) consortium, which uses the transit method to detect exoplanets. The star is older than the Sun and slightly depleted in heavy elements, with close to average starspot activity. Despite its advanced age, the star rotates rapidly, a phenomenon attributed to tidal spin-up caused by a giant planet on a close orbit.
In 2011, a transiting hot superjovian planet, designated WASP-50b, was detected around the star. This planet was later named Maeping in 2019. In 2022, the planet's albedo was found to be no more than 0.44, meaning it reflects less than 44% of the light from its host star, which helps constrain its equilibrium temperature.
The system was selected for the 2019 NameExoWorlds campaign during the 100th anniversary of the IAU, with Thailand assigned to name the star and planet. The approved names, Chaophraya for the star and Maeping for the planet, were proposed by Duangrat Wichiansri following a national vote conducted by NARIT in 2019. The names reference the Chao Phraya and Mae Ping rivers in Thailand.
Reader's Guide
WASP-50 (Chaophraya) holds significance as a G-type star that, despite being older than the Sun and slightly metal-poor, exhibits rapid rotation due to tidal interactions with its close-orbiting giant planet. This makes it a valuable case study for understanding how stellar rotation can be influenced by planetary companions. The detection of its planet, WASP-50b (Maeping), in 2011 added to the growing catalog of hot superjovian exoplanets discovered via the transit method. The 2022 measurement of the planet's low albedo (≤0.44) provides constraints on its atmospheric properties and equilibrium temperature. Culturally, the star's naming as Chaophraya through the IAU's NameExoWorlds campaign highlights the involvement of Thailand in exoplanetary science, with the names chosen by public vote and proposed by Duangrat Wichiansri. The star's legacy lies in its dual role as both a scientific object for studying star-planet interactions and a symbol of international participation in astronomy.
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