Using Webb’s NIRSpec for Analysis
Astronomers used Webb’s Near-Infrared Spectrograph (NIRSpec) to study WASP-39 b’s atmosphere. This powerful tool allowed researchers to observe temperature differences and cloud cover variations between the planet’s morning and evening sides.
Source: NASA
The data was collected under the Early Release Science program 1366, designed to help scientists maximize Webb’s capabilities.
Temperature Differences Confirmed
The study confirmed that WASP-39 b’s eternal evening is about 300 degrees Fahrenheit hotter than its morning.
Source: Freepik
Specifically, the evening side reaches temperatures of 1,450 degrees Fahrenheit (800 degrees Celsius), while the morning side is cooler at 1,150 degrees Fahrenheit (600 degrees Celsius). This significant temperature difference aligns with previous models.
The Role of Cloud Cover
Researchers found that the morning side of WASP-39 b is cloudier compared to the evening side.
Source: Freepik
The varying cloud cover is one of the factors contributing to the temperature differences. The cloudier morning side reflects more sunlight, helping it stay cooler.
Filtering Starlight
To understand these differences, scientists analyzed the 2- to 5-micron transmission spectrum of WASP-39 b.
Source: Wikimedia
The method involves comparing starlight filtered through the planet’s atmosphere as it moves in front of its star to the unfiltered starlight when the planet is beside the star. This comparison reveals crucial details about the atmosphere’s properties.
Gas Circulation Patterns
The study attributes the temperature differences to gas circulation patterns on the planet. Hot gas from the dayside moves to the nightside via a powerful equatorial jet stream.
Source: Freepik
As a result, the evening side is bombarded with hot air, while the morning side receives cooler air from the night side.
Extreme Wind Speeds
Researchers used General Circulation Models to predict wind speeds on WASP-39 b. These models, similar to those used for Earth’s weather, suggest that wind speeds can reach thousands of miles per hour.
Source: Jem Sanchez/Pexels
The extreme temperature and pressure differences drive these high-speed winds.
Detailed Atmospheric Structure
The study provides 3D information on WASP-39 b’s atmosphere.
Source: NASA/Wikimedia Commons
Since the evening edge is hotter, it is also puffier, creating a small swell at the terminator approaching the night side.
Importance of WASP-39 b
WASP-39 b has become a benchmark planet for studying exoplanet atmospheres with the James Webb Space Telescope.
Source: Wikimedia
Its inflated, puffy atmosphere produces strong signals, making it an ideal candidate for detailed analysis and comparison.
Future Research Directions
The researchers plan to use the same method of analysis on other tidally locked hot Jupiters.
Source: Wikimedia Commons
This work is part of Webb Cycle 2 General Observers Program 3969, aiming to expand our knowledge of atmospheric differences on exoplanets.
Importance of Accuracy
Néstor Espinoza, the lead author, emphasized the precision of Webb’s instruments: “Any tiny movement in the instrument or with the observatory while collecting data would have severely limited our ability to make this detection.”
Source: DC Studio, Freepik
“It must be extraordinarily precise, and Webb is just that.”
Broader Implications
The findings from WASP-39 b offer valuable insights into the atmospheric dynamics of exoplanets.
Source: NASA
Understanding these processes helps scientists better predict the climates and potential habitability of distant worlds, further expanding our knowledge of the universe.