TRAPPIST-1 b, one of seven rocky planets orbiting the star TRAPPIST-1, continues to attract astronomers’ attention. Located just 40 light years away from us, this planetary system is unique. This is a rare opportunity to study seven Earth-like planets, three of which are in the habitable zone where liquid water could exist on their surfaces. Researchers now have a deeper understanding of TRAPPIST-1 b using the James Webb Space Telescope (JWST).

TRAPPIST-1 observations b

A team led by Elsa Ducrot from the Commissariat aux Énergies Atomiques (CEA) in France analyzed thermal infrared measurements taken by JWST’s Mid-Infrared (MIRI) camera. The researchers, including experts from the Max Planck Institute for Astronomy (MPIA), published their findings in the journal. Nature Astronomy. The results challenge previous conclusions and raise questions about the planet’s atmosphere and surface activity.

Geologically active surface?

In last year’s study, TRAPPIST-1 b was described as a dark, rocky planet with no atmosphere. But recent measurements provide new clues.

“The idea of ​​a rocky planet with no atmosphere and a highly eroded surface contradicts existing measurements,” said MPIA astronomer Jeroen Bowman. “So we think the planet is covered in relatively unchanged material.”

The surfaces of rocky planets are often eroded by stellar radiation and meteorite impacts. However, the surface of TRAPPIST-1 b appears extremely young. Researchers believe the rock on its surface may only be 1,000 years old; This is much less than the estimated age of the planet, which is several billion years.

Significant geological activity at TRAPPIST-1 b

This discovery points to dramatic geological activity. The planet’s crust may undergo constant changes caused by extreme volcanism or plate tectonics. Bowman noted that TRAPPIST-1 b can store internal heat similar to Earth. Tidal forces from the host star and nearby planets can deform its surface, creating internal friction and heat, a phenomenon observed on Jupiter’s volcanic moon Io. Heating from the star’s magnetic field may also contribute.

Secret atmosphere?

Could TRAPPIST-1 b still have an atmosphere? Thomas Henning, MPIA director emeritus and co-author of the MIRI tool, suggested another possibility.

“Contrary to previous ideas, there are conditions under which a planet could have a thick atmosphere rich in carbon dioxide (CO).₂), Henning said. The determining factor may be haze – hydrocarbon smog formed in the upper layers of the atmosphere.

The study involved two observing programs measuring the planet’s brightness at 12.8 and 15 micrometers. These wavelengths are sensitive to CO absorption₂. Because no eclipse occurred, researchers initially concluded that TRAPPIST-1 b had no atmosphere. But new model calculations show that fog can change the scenario.

Effect of fog on planetary atmospheres

The haze absorbs starlight and warms the upper atmosphere, potentially altering the expected temperature pattern. Instead of a warmer surface layer, the upper atmosphere may warm up and emit infrared radiation (greenhouse effect). Henning compares this to Saturn’s moon Titan, where ultraviolet radiation turns carbon-rich gases into fog.

Despite the possibility, researchers note important differences. Titan’s atmosphere is rich in methane, while TRAPPIST-1 b requires CO₂. Additionally, red dwarf stars such as TRAPPIST-1 emit intense radiation and stellar winds that can destroy planets’ atmospheres for billions of years.

Eclipses and Occultations: Research Tools

The study contributed to the positive orientation of TRAPPIST-1. Seven planets periodically pass in front of the star from Earth, dimming its light; this is a phenomenon known as migration. These events provide valuable data about the planet’s size, composition, and atmosphere through a technique called transit spectroscopy.

However, transit spectroscopy has limitations for systems such as TRAPPIST-1. Cool red dwarf stars often exhibit starspots and flares that can interfere with measurements. To solve this problem, the researchers observed the thermal infrared emission of TRAPPIST-1 b. Scientists focused on the planet’s bright daylight just before and after it disappeared behind the star, collecting detailed information about its surface and atmosphere.

This method, known as secondary eclipse measurement, is time consuming. Current observations lasted about 48 hours but are not long enough to confirm the existence of an atmosphere.

Persistent questions about TRAPPIST-1 b

NASA recently approved the ambitious Rocky Worlds program, which consists of 500 hours of JWST observations to study rocky planets around nearby stars. Researchers hope this program will help resolve persistent questions about TRAPPIST-1 b.

One promising method involves tracking a planet’s entire orbit to create a phase curve, a map of its temperature distribution. This approach reveals how heat moves across the planet’s surface. If heat is distributed equally between the day and night sides, an atmosphere is likely present. If the temperature changes sharply, this indicates insufficient thermal insulation of the atmosphere.

The research team has already started this phase curve measurement for TRAPPIST-1 b. They are trying to confirm whether the planet has an atmosphere by analyzing changes in temperature.

“The presence or absence of an atmosphere will significantly impact our understanding of TRAPPIST-1 b and similar exoplanets,” Bauman said.

Wider implications of the study

The study highlights the difficulties of investigating rocky planets, even with advanced instruments like JWST. Compared to gas giants, rocky planets have a thinner atmosphere that creates weak signals. Despite the obstacles, TRAPPIST-1 b provides a valuable practical example.

The resulting data also makes it possible to understand exoplanets orbiting red dwarfs, the most common stars in the galaxy. Understanding their atmospheres, geological activity, and potential habitability will shape future research and exploration.

The research is a result of international collaboration. Researchers from MPIA, CEA and institutions across Europe contributed to this original work. The MIRI instrument itself is a product of the efforts of ESA member states and organizations such as the Max Planck Society.

TRAPPIST-1 b remains a mystery. A geologically active world with a young surface? Can it hide thick, rich CO? ₂ Is the atmosphere covered in haze?

The answers will require further observation. Thanks to JWST’s capabilities and the ongoing Rocky Worlds program, astronomers are closer than ever to solving these mysteries. The study was published in the journal Nature Astronomy.