In the search for planets beyond our solar system, many scientists focus on finding worlds that could support life.
But others are drawn to the extreme and exotic—like HAT-P-70 b, an “ultra-hot Jupiter” orbiting a distant star.
This massive gas giant is nearly twice the size of Jupiter and so close to its star that it completes an orbit in just 2.7 Earth days.
Its surface temperature is a blistering 2,300°C (about 4,200°F), making it one of the hottest planets ever discovered.
A team of astronomers, led by Adam Langeveld from Johns Hopkins University and including Emily Deibert of Gemini South in Chile, studied HAT-P-70 b using a powerful new instrument called GHOST.
Short for the Gemini High-resolution Optical SpecTrograph, GHOST is attached to the Gemini South telescope, part of the International Gemini Observatory operated by NSF NOIRLab.
This cutting-edge device allows scientists to observe a wide range of wavelengths with high sensitivity and clarity, providing an unprecedented look at the atmospheres of distant worlds.
The team observed the planet as it passed in front of its star, a process called a transit.
As starlight filters through the planet’s atmosphere, certain chemicals absorb specific wavelengths of light, creating patterns that can be detected and analyzed—a technique known as spectroscopy.
GHOST’s remarkable sensitivity allowed the scientists to detect ionized calcium in the upper atmosphere of HAT-P-70 b, a form of calcium that only exists at extremely high temperatures.
Even more impressively, the instrument allowed researchers to track how the calcium signal changed from the planet’s day side to its night side.
This revealed something extraordinary: fierce winds blowing at speeds of up to 18,000 kilometers per hour (11,000 miles per hour), rushing from the searing hot dayside to the cooler nightside.
Deibert said the level of detail GHOST provided was surprising. The team could detect tiny changes in specific absorption lines, giving them insight into different layers of the atmosphere—something that’s rarely been possible in past exoplanet studies.
The data also suggested that HAT-P-70 b is lighter than previously thought, a key discovery for scientists trying to understand how such planets form and evolve.
By comparing the amounts of elements like calcium and iron (from rocky materials) to lighter elements like carbon and water, researchers can begin to piece together the history of these alien worlds.
This study marks just the beginning for GHOST. With years of observation time secured through Gemini’s Large Programs, Langeveld, Deibert, and their team hope to unlock more secrets about the extreme worlds that exist far beyond our solar system.
