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Alien Planet Discovery: LHS 1140 b Could Be Our Next Earth!


In an exciting development for the hunt for habitable worlds, recent observations using the James Webb Space Telescope (JWST) have shed new light on the exoplanet LHS 1140 b. Located just a cosmic stone’s throw away, LHS 1140 b is one of the closest temperate planets to Earth and lies in the so-called “habitable zone,” where conditions might be right for liquid water.

What’s Special About LHS 1140 b?

LHS 1140 b is particularly intriguing because its size places it in a unique category. It’s larger than Earth but not quite big enough to be a mini-Neptune, a type of planet often swathed in thick hydrogen atmospheres. This “radius valley” makes scientists wonder: Is LHS 1140 b a rocky super-Earth, or does it have a thin envelope of hydrogen, or perhaps is it a water world with significant amounts of water by mass?

Unraveling the Mysteries with JWST

Using JWST’s NIRISS instrument, astronomers observed two transits of LHS 1140 b, where the planet passes in front of its star, offering a glimpse into its atmosphere. One of these observations even caught a transit of a neighboring planet, LHS 1140 c, providing a bonus data set. The main tool here was transmission spectroscopy, which can identify different atmospheric components by the way they absorb starlight.

Key Findings

  1. Stellar Activity Insight: The data revealed strong signs of “unocculted faculae,” bright spots on the star’s surface that weren’t obscured during the transit. These bright areas covered about 20% of the star’s visible surface and were a significant factor in interpreting the spectral data.

  2. Atmospheric Clues: There’s tentative evidence that LHS 1140 b might have a nitrogen-dominated atmosphere. This was suggested by a spectral feature around 2.2 micrometers, likely caused by nitrogen-nitrogen collision-induced absorption. This finding is crucial because it points to a heavy, high molecular weight atmosphere, unlike the light, hydrogen-dominated atmospheres of mini-Neptunes.

  3. Ruled Out Scenarios: Various compositions of hydrogen-rich atmospheres were ruled out with high confidence. This suggests that if LHS 1140 b has an atmosphere, it is more likely similar to Earth’s in terms of molecular weight, possibly a thick layer of nitrogen with traces of other gases like carbon dioxide.

Why It Matters

Understanding the atmosphere of LHS 1140 b is a significant step toward finding out if it could support life. An atmosphere rich in nitrogen and possibly water could create conditions favorable for habitability. This discovery also highlights the power of JWST in studying distant worlds, offering more detailed insights than ever before.

What’s Next?

To confirm these findings, more observations are needed. Future studies could involve additional transits and perhaps even secondary eclipse observations (when the planet passes behind its star) to get more information about the atmospheric composition and surface conditions.

A New Hope for Finding Habitable Worlds

LHS 1140 b stands out as a prime candidate for further study in the quest to find habitable worlds outside our solar system. Its relatively close proximity and unique characteristics make it a fascinating target. The tantalizing hints of a secondary atmosphere, possibly rich in nitrogen, opens up exciting possibilities for what this planet might be like. With JWST and other upcoming missions, we are on the brink of discovering more about these distant worlds and their potential to host life.

Read the paper.