WASP-189 b
An ultra-hot Jupiter with a polar orbit and extreme temperatures.
WASP-189 b (designated HD 133112 b) is an ultra-hot Jupiter orbiting the A-type star WASP-189, roughly 322 light-years away in the constellation Libra. It was first detected in 2018 via the transit method, and the CHEOPS satellite observed it in 2020. The planet has a mass about 1.99 times that of Jupiter and a radius about 1.6 times Jupiter’s. It follows a polar orbit around its rapidly rotating A6IV-V star at a distance of 0.05 AU, completing one revolution every 2.72 days.
Temperature estimates from CHEOPS vary depending on heat redistribution. Assuming inefficient redistribution, the temperature reaches around 3200 °C; with efficient redistribution and zero albedo, it is about 2367 °F. These extremes classify WASP-189 b as an ultra-hot Jupiter and one of the hottest exoplanets known.
Its atmosphere has been studied by CHEOPS and the Colorado Ultraviolet Transit Experiment (CUTE). The high temperatures keep refractory elements gaseous, allowing detection of many metals and volatiles. CHEOPS found titanium oxide (TiO), vanadium oxide (VO), and metals including chromium (Cr), magnesium (Mg), vanadium (V), and manganese (Mn), as well as singly ionized iron (Fe, Fe⁺, Fe II) and titanium (Ti, Ti⁺). The Immersion Grating Infrared Spectrometer (IGRINS) on Gemini South detected neutral iron (Fe I), magnesium (Mg I), silicon (Si I), water (H₂O), carbon monoxide (CO), and hydroxyl (OH).
Quick Facts
- Discovered
- 2018
- Discovery Method
- Transit
- Semimajor
- 0.05053
- Period
- 2.72 d
- Star
- WASP-189 (HD 133112)
- Mass
- 1.99
- Albedo
- <0.48
- Single Temperature
- 3470 K
Facts from the source article.
Lore & Background
WASP-189 b was first discovered in 2018 using the transit method. In 2020, the CHEOPS spacecraft observed it, providing detailed data on its temperature and atmosphere. The planet orbits a rapidly rotating A6IV-V star at a distance of 0.05 AU, completing an orbit every 2.72 days. Its orbit is polar relative to the star.
The planet has a mass of about 1.99 Jupiter masses and a radius of about 1.6 Jupiter radii. Temperature estimates vary depending on assumptions: assuming inefficient heat redistribution, the temperature is around 3200 °C; assuming efficient heat redistribution and zero albedo, the temperature is about 2367 °F. These values classify WASP-189 b as an ultra-hot Jupiter.
Its atmosphere has been studied by CHEOPS and the CUTE spacecraft. Observations reveal the presence of titanium oxide, vanadium oxide, and metals such as chromium, magnesium, vanadium, and manganese. Singly ionized iron and titanium were also detected. The IGRINS instrument on Gemini South found neutral iron, magnesium, silicon, water, carbon monoxide, and hydroxyl.
Reader's Guide
WASP-189 b is significant as one of the hottest exoplanets known, with temperatures reaching up to 3200 °C under certain assumptions. Its extreme heat allows the study of refractory elements that remain gaseous at high temperatures, providing insights into planetary composition under conditions not found in the Solar System. The detection of titanium oxide and vanadium oxide in its atmosphere is notable, as these compounds are typically solid at lower temperatures. The polar orbit of the planet around its rapidly rotating A-type star is also unusual, offering clues about planetary system formation and dynamics. Observations by CHEOPS and CUTE have contributed to understanding the atmospheric chemistry of ultra-hot Jupiters, including the presence of ionized metals and volatile molecules. The planet's legacy lies in advancing knowledge of atmospheric processes on highly irradiated gas giants and the behavior of metals in extreme environments.
Did You Know?
- WASP-189 b orbits its star in a polar orbit.
- Its temperature may reach around 3200 °C assuming inefficient heat redistribution.
- The atmosphere contains titanium oxide and vanadium oxide.
- It was observed by the CHEOPS spacecraft in 2020.
Frequently Asked Questions
What is WASP-189 b?
WASP-189 b, also catalogued as HD 133112 b, is an ultra-hot Jupiter that circles the A-type star WASP-189 in the constellation Libra. It sits roughly 322 light-years from Earth and was first spotted in 2018 using the transit method.
How big and massive is WASP-189 b?
The planet packs about 1.99 times Jupiter's mass into a radius roughly 1.6 times Jupiter's, giving it a puffy, inflated profile typical of close-in giant worlds. That low density hints at prolonged heating by its host star over billions of years.
What makes WASP-189 b's orbit unusual?
Rather than hugging its star's equator like most transiting exoplanets, WASP-189 b traces a polar orbit around its rapidly spinning A6IV-V host. It completes one lap every 2.72 days at a mere 0.05 AU, an incredibly tight path that drives its scorching temperatures.
How was WASP-189 b discovered and observed?
Astronomers first detected the planet in 2018 by watching its host star dim slightly as the giant world passed across the disk. The CHEOPS space telescope later targeted WASP-189 b in 2020 to refine its properties and probe how heat circulates across its atmosphere.
Why is WASP-189 b important to exoplanet science?
Its polar orbit around a fast-rotating A-type star makes it a rare test case for understanding how planets can end up misaligned with their host's spin axis. Combined with its ultra-hot temperature and puffy radius, it gives researchers a natural laboratory for studying atmospheric dynamics under extreme conditions.
More in Transiting Exoplanets, Part 4 1-24
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