Summary
JWST thermal emission spectroscopy (5–12 µm, MIRI instrument) of the rocky super-Earth LHS 3844 b reveals a dark, featureless surface with no detectable atmosphere. The mid-infrared spectrum matches low-silica compositions — space-weathered basalt or olivine-rich rock — rather than a fresh silicate crust, suggesting the planet resembles Mercury or Earth’s Moon. Upper limits rule out 100 mbar of CO₂ and 10 µbar of SO₂, eliminating any significant volcanic gas accumulation. The absence of an Earth-like silicate crust implies plate tectonics do not apply to this world. The result reinforces the pattern that short-period rocky planets around M dwarfs tend to lose their atmospheres rapidly, constraining biosignature-hunting target selection.
Key Claims
- No detectable atmosphere: strict upper limits of 100 mbar CO₂ and 10 µbar SO₂. (Zieba et al.)
- Surface spectrum consistent with space-weathered basalt or olivine-rich material, not fresh silicate powder. (Zieba et al.)
- Planet resembles Mercury or Earth’s Moon in surface composition and weathering state. (Zieba et al.)
- Absence of silicate crust implies Earth-like plate tectonics do not apply. (Sebastian Zieba, CfA Harvard & Smithsonian)
- LHS 3844 b: 30% larger than Earth, dayside ~1000 K, ~11-hour orbit, tidally locked, 48.5 light-years away around an M dwarf. (Zieba et al.)
- Supports the broader pattern of rapid atmospheric loss for close-in rocky planets around M dwarfs. (Zieba et al.)
Notable Quotes
“Thanks to the amazing sensitivity of JWST, we can detect light coming directly from the surface of this distant rocky planet.” — Laura Kreidberg (MPIA, Principal Investigator)
“Since LHS 3844 b lacks such a silicate crust, one may conclude that Earth-like plate tectonics does not apply to this planet.” — Sebastian Zieba (CfA Harvard & Smithsonian)