LHS 1140 c Archives - Astrobiology

Models of mass-loss rate, outflow temperature, and H:He ratio for LHS 1140b in 2024. (A) Models of atmospheric mass-loss rate as a function of outflow temperature, 𝑇wind. Color indicates the normalized likelihood calculation, where zero corresponds to the maximum likelihood. Black contours indicate 1𝜎 and 3𝜎 derivations from the maximum likelihood. Data points with 1𝜎 error bars are the best-fitting values from the MCMC analysis of the 2024 spectrum of LHS 1140b, assuming an SED normalized to GJ 699 (black) or GJ 1132 (green). All models assumed the GJ 1132-normalized SED and fixed 𝑣wind the best-fitting value from the MCMC analysis. The dashed gray line shows a theoretical upper limit on the escape rate (see text). The dashed red line shows the theoretical minimum escape rate required to drag atomic oxygen in the outflow. The dashed black and green lines show the energy-limited escape rates calculated with the SEDs normalized by GJ 699 and GJ 1132, respectively. (B) Same as panel A, but as a function of the H:He ratio. Data points with dotted error bars assumed 10 times higher stellar XUV flux. -- [astro-ph.EP]

Habitable Zones

Helium Escaping From The Atmosphere Of A Nearby Rocky Exoplanet Orbiting In A Habitable Zone

by Keith CowingJuly 21, 2026July 21, 2026

[astro-ph.EP] Observations of highly irradiated gas giant exoplanets have shown helium escaping from their atmospheres. There is limited evidence for atmospheres on rocky exoplanets, perhaps because they have already escaped.

In this artist's rendering, the exoplanet LHS 1140 b is shown in the foreground, surrounded by a helium-rich atmosphere. Another nearby rocky planet orbits the same cool red dwarf star in the distance. This new study provides the strongest evidence yet that LHS 1140 b has retained an atmosphere, representing a milestone step toward the discovery of Earth-like rocky planets beyond our Solar System. -- Carnegie Science

Habitable Zones

Detected: Rocky, Habitable-zone Exoplanet With An Atmosphere

by Keith CowingJuly 17, 2026July 17, 2026

[Carnegie Science] A team of scientists led by Harvard University’s Collin Cherubim and including Shreyas Vissapragada and other Carnegie astronomers has detected evidence of an atmosphere on a rocky planet […]

Best-fit model for the three light curves extracted using aperture photometry with Eureka!. Outliers beyond 4 σ are clipped. -- astro-ph.EP

Astrogeology, Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release

Reanalysis Of The Eclipses Of LHS 1140 c: No Evidence Of An Atmosphere And Implications For The Internal Structure Of The Planet

by Keith CowingOctober 24, 2025October 22, 2025

We present the reanalysis of three 15 micron JWST/MIRI secondary eclipses of LHS 1140 c, a warm super-Earth (Rp = 1.272 R⊕) in a 3.78-day orbit around an M4.5 dwarf.

Regime diagram for high molecular weight escape in terms of the polytropic index 0.65 ≤ γ ≤ 0.95 and the hydrodynamic escape parameter 10 ≤ λ0 ≤ 400. The heat map indicates the ratio of sonic to base temperatures 10 − 100. Contours of uniform ratio of sonic to base radius (red-dashed) and uniform sonic to base density in log units (green dashed). The Young Sun Earth (c.f. Figures 4 & 8B) and Young Sun Mars (see Figures 5 & 8A) calculations are represented by images of each planet. This figure can be compared to the solution space of polytropic solutions (Fig 3). For large enough λ0, the polytropic model of steep XUV inversions breaks down because line cooling will begin to dominate over advection. The overlaying pink patch is to illustrate that the shift is broad and dependent on boundary conditions and dimensional parameters. Rightward of the transition, the collisional radiative thermostat will control the resulting global ion outflow (see Section 5). -- astro-ph.EP

Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, TRAPPIST-1

Novel Physics of Escaping Secondary Atmospheres May Shape the Cosmic Shoreline

by Keith CowingDecember 9, 2024December 9, 2024

Recent James Webb Space Telescope observations of cool, rocky exoplanets reveal a probable lack of thick atmospheres, suggesting prevalent escape of the secondary atmospheres formed after losing primordial hydrogen.

Spectrophotometric transit fits of LHS 1140 b for visit 1 (UT2023-12-01, left) and visit 2 (UT2023-12-26, right) and LHS 1140 c for visit 2 only. The broadband (‘white’) light curves are shown in top panels with the best-fit full model (transit + systematics) shown in black and systematics component only in pink (scaled 10× for clarity). For both visits, examples of 10 systematics-corrected spectroscopic bins are depicted with colored points in bottom panels. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, TRAPPIST-1, Water/Hycean Worlds & Oceanography

Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWST/NIRISS

by Keith CowingJune 24, 2024June 24, 2024

LHS 1140 b is the second-closest temperate transiting planet to the Earth with an equilibrium temperature low enough to support surface liquid water.

Results of Global Climate Model (GCM) simulations of LHS 1140 b assuming an Earth-like atmosphere (1 bar N2, 400 ppm CO2; panels a, c, d, e) and a thick CO2-dominated atmosphere (5 bar CO2; panels b, f, g, h). Panels a, b: Surface temperature maps of LHS 1140 b. The black line indicates the line of stability between liquid water and sea ice. The extent of the ice-free ocean strongly depends on the amount of CO2 in the atmosphere. Panels c, d, e, f, g, and h: Vertical profiles of the atmospheric temperatures, water vapor, and cloud mixing ratios (both H2O and CO2 ice clouds). The solid bold lines indicate the global mean vertical profiles and the dotted lines indicate terminator vertical profiles (impacting transit spectra). -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

New Mass and Radius Constraints On The LHS 1140 Planets — LHS 1140 b Is Either A Temperate Mini-Neptune Or A Water World

by Keith CowingOctober 30, 2023October 30, 2023

LHS 1140 b and c are two small temperate exoplanets transiting a nearby M4.5 dwarf. The planetary system was observed with multiple facilities since its discovery in 2017, including MEarth, […]