M-dwarf Archives

Image description: Infographic titled, “Rocky Exoplanet TRAPPIST-1 b Dayside Temperature Comparison, MIRI F1500W” showing five planets plotted along a horizontal temperature scale: Earth, TRAPPIST-1 b, Mercury, and two different models of TRAPPIST-1 b. The temperature scale is labeled in kelvins and degrees Fahrenheit, and ranges from 0 kelvins (negative 459 degrees Fahrenheit) at the left to 800 kelvins (980 degrees Fahrenheit at the right). The planets are plotted along the temperature scale at the following temperatures: Earth Measured at 290 kelvins (60 degrees Fahrenheit); TRAPPIST-1 b Measured at about 500 kelvins and 445 degrees Fahrenheit; “Mercury Measured” at 700 kelvins (800 degrees Fahrenheit). TRAPPIST-1 b Model with atmosphere is plotted at 400 kelvins (260 degrees Fahrenheit); TRAPPIST-1 b Model with no atmosphere is plotted at about 510 kelvins and 455 degrees Fahrenheit. TRAPPIST-1 b Measured is plotted at almost the same temperature as TRAPPIST-1 b Model with no atmosphere.

Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release, TRAPPIST-1

Webb Measures The Temperature Of Rocky Exoplanet TRAPPIST-1 b

by Keith CowingOctober 2, 2023

Webb measured the dayside temperature of rocky exoplanet TRAPPIST-1 b and found it to be about 450 degrees F (227 degrees C), suggesting it has no significant atmosphere.

Best-fit system in each modeling scenario compared to the true TRAPPIST-1 system using only Filippazzo et al. (2015) priors. The symbol size corresponds to the planet size, and the color indicates albedo. Horizontal bars indicate the uncertainty on a planet’s semi-major axis. Each modeling scenario is labeled with the number of planets included, the computed evidence, and its significance against the best-fit model. We use transparency to demonstrate which models are ruled out by > 3σ confidence. The vertical dashed lines indicate the limits of our semi-major axis bounds. -- astro-ph.EP

Astronomy & Telescopes, Status Report, TRAPPIST-1

On the Effectiveness of the Planetary Infrared Excess (PIE) Technique to Retrieve the Parameters of Multiplanet Systems around M dwarfs: A Case Study on the TRAPPIST-1 System

by Keith CowingOctober 1, 2023October 1, 2023

The planetary infrared excess (PIE) technique has the potential to efficiently detect and characterize the thermal spectra of both transiting and non-transiting exoplanets. However, the technique has not been evaluated […]

The transmission spectrum atmospheric effective altitude is plotted against wavelength between 0.2 µm and 11 µm for the P19 PI (orange), P19 10% PAL (brown), P19 1% PAL (yellow), and P19 0.1% PAL (red) simulations, and the W21 PI (light blue), W21 10% PAL (blue), W21 1% PAL (lilac), and W21 0.1% PAL (grey) simulations. The non-tidally locked cases are excluded for clarity, but show little differences compared to the equivalent tidally locked case. The transit depth, in terms of contrast with respect to the star, is indicated on the right vertical axis in parts per million (ppm). The spectra are binned to a spectral resolving power of R = 250. Spectral features are indicated in grey. The wavelength range of the proposed Habitable Worlds Observatory (HWO; blue shaded region), and that of the JWST NIRSpec instrument (yellow shaded region), are shown. They overlap in the green shaded region. The wavelength range of the JWST MIRI instrument is indicated in the magenta shaded region. The wavelength spacing between 0.2 – 1 µm is changed between 1 – 11 µm in order to clearly show the UV and visible regions. The black bar represents the uncertainty that would be present on a measurement that has reached the noise floor of the instrument, where the noise floor is indicated as 5 ppm. Note this error bar is an estimate of the performance of the telescope and does not indicate a measurement. -- astro-ph.EP

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

Degenerate Interpretations Of O3 Spectral Features In Exoplanet Atmosphere Observations Due To Stellar UV Uncertainties: A 3D Case Study With TRAPPIST-1e

by Keith CowingOctober 1, 2023October 1, 2023

TRAPPIST-1e is a potentially habitable terrestrial exoplanet orbiting an ultra-cool M Dwarf star and is a key target for observations with the James Webb Space Telescope (JWST). One-dimensional photochemical modelling […]

The incident spectral fluxes, fp (λ; Ts, asp) for a range of stellar temperatures

Biophysics, Biosignatures & Paleobiology, Europa, Habitable Zones, Plant Biology, Status Report

Thermodynamic Limits On Oxygenic Photosynthesis Around M-dwarf Stars: Generalized Models And Strategies For Optimization

by Keith CowingSeptember 25, 2023September 25, 2023

We explore the feasibility and potential characteristics of photosynthetic light-harvesting on exo-planets orbiting in the habitable zone of low mass stars (<1 M⊙).

A. thaliana seedlings acclimation experiment. (A) Images of A. thaliana seedlings at 0 and after 9 days under the three different light conditions; (B) Fresh weight of A. thaliana seedlings at the end of the experiment under the three different light conditions. The large bar shows the mean value of the data. The small bars show the standard deviation of the samples (8 biological replicates). p-values of the statistical analysis are reported on the graph if below the significance threshold (one-way ANOVA, significance was set at p < 0.05). SOL, solar light; M7, M-dwarf light; FR, far-red light. Scale bar = 10 mm. -- Life

Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Habitable Zones, Plant Biology, Space Agriculture, Space Life Science, Status Report

Growth and Photosynthetic Efficiency of Microalgae and Plants with Different Levels of Complexity Exposed to a Simulated M-Dwarf Starlight

by Keith CowingSeptember 6, 2023September 6, 2023

Oxygenic photosynthetic organisms (OPOs) are primary producers on Earth and generate surface and atmospheric biosignatures, making them ideal targets to search for life from remote on Earth-like exoplanets orbiting stars […]

Three dimensional view of the magnetised stellar wind for Models I and II. The surface magnetic field from March-June 2016 reconstructed by Bellotti et al. (2023) is used at the boundary of the models. The grey streamlines are the magnetic field lines embedded in the wind. The rotation axis of the star is along the z⋆-axis. The two-dimensional cut is placed at the x⋆z⋆ plane, and for indication, the orbital distance of the planet is shown by the translucent sphere at 14.56 R⋆ ≃ 0.028 au. The contour shows the wind velocity and the Alfvén surface is shown by the translucent outer surface. Models I and II predict stellar wind mass-loss rates of 1.1 × 10−15 M⊙ yr−1 and 2.5 × 10−14 M⊙ yr−1 -- astro-ph.SR .

Exoplanets, -moons, -comets, Extinction events, Habitable Zones, Space Weather & Heliophysics, Status Report

The Space Weather Around The Exoplanet GJ 436 b. II. Stellar Wind-exoplanet Interactions

by Keith CowingSeptember 5, 2023September 5, 2023

The M dwarf star GJ 436 hosts a warm-Neptune that is losing substantial amount of atmosphere, which is then shaped by the interactions with the wind of the host star. […]

𝐻-band (top) and 𝐾-band (bottom) spectra of 2M0437b. The dark blue points are the reduced spectrum produced by the OSIRIS pipeline, the dark blue line is the 21-point running median, the magenta curve is a model of the spectrum to further correct for telluric absorption using a spectrum of an A0 star, and the green points and line are the corrected spectrum and its 21-point running median. The grey line is a model transmission spectrum for the atmosphere over Maunakea for an airmass of 1.5 and water vapor column of 1.6 mm (courtsey Gemini Orbservatory, Lord 1992). The absorption functions of key molecules (H2O, CO, CH4, HCN) computed using the HITRAN database (Mikhailenko et al. 2005; Gordon et al. 2022) and normalized by the maximum for that molecule in each bandpass are plotted at the top (blue, black, red, and orange lines, respectively. The vertical dotted lines mark H Brackett lines and the Na I doublet, and spectral features of molecules of interest are labeled. -- astro-ph.EP

Astrochemistry, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

CO, H2O, And CH4 In The Dusty Atmosphere Of A ≤5 Myr-old Exoplanet

by Keith CowingAugust 30, 2023August 30, 2023

Very young massive planets are sufficiently luminous by their internal heat of formation to permit detailed studies, including spectroscopy of their atmospheres with large telescopes at sufficient resolution (λ/Δλ≳1000) to […]

pEW(Paβ) shown as a function of Teff. Grey dots represent median(pEW(Paβ)) for each star, the coloured circles represent the mean of these median(pEW(Paβ)) measurements for each Teff interval as introduced in the main text. The colours are chosen as in Figs. 3 and 5 to simplify comparison. -- astro-ph.SR

Astronomy & Telescopes, Exoplanets, -moons, -comets, Space Weather & Heliophysics, Status Report

The CARMENES Search For Exoplanets Around M Dwarfs. Behaviour Of The Paschen Lines During Flares And Quiescence

by Keith CowingAugust 16, 2023August 16, 2023

The hydrogen Paschen lines are known activity indicators, but studies of them in M~dwarfs during quiescence are as rare as their reports in flare studies. This situation is mostly caused […]

Flowchart illustrating the three possible stages in our box model of M-Earth evolution. (a) Surface magma ocean (MO).

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Lava / magma ocean / Volcanic Worlds, Status Report, Water/Hycean Worlds & Oceanography

The Role of Magma Oceans in Maintaining Surface Water on Rocky Planets Orbiting M-Dwarfs

by Keith CowingAugust 3, 2023May 11, 2024

Earth-like planets orbiting M-dwarf stars, M-Earths, are currently the best targets to search for signatures of life. Life as we know it requires water. The habitability of M-Earths is jeopardized […]

This artist's illustration shows a planet (dark silhouette) passing in front of the red dwarf star AU Microscopii. The planet is so close to the eruptive star a ferocious blast of stellar wind and blistering ultraviolet radiation is heating the planet's hydrogen atmosphere, causing it to escape into space. Four times Earth's diameter, the planet is slowly evaporating its atmosphere, which stretches out linearly along its orbital path. This process may eventually leave behind a rocky core. The illustration is based on measurements made by the Hubble Space Telescope. Credits: NASA, ESA, and Joseph Olmsted (STScI)

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Press Release, Space Weather & Heliophysics

A Young Super-Earth Orbiting Red Dwarf AU Microscopii Is Evaporating

by Keith CowingJuly 29, 2023July 29, 2023

A young planet whirling around a petulant red dwarf star is changing in unpredictable ways orbit-by-orbit. It is so close to its parent star that it experiences a consistent, torrential […]

M-dwarf

Webb Measures The Temperature Of Rocky Exoplanet TRAPPIST-1 b

On the Effectiveness of the Planetary Infrared Excess (PIE) Technique to Retrieve the Parameters of Multiplanet Systems around M dwarfs: A Case Study on the TRAPPIST-1 System

Degenerate Interpretations Of O3 Spectral Features In Exoplanet Atmosphere Observations Due To Stellar UV Uncertainties: A 3D Case Study With TRAPPIST-1e

Thermodynamic Limits On Oxygenic Photosynthesis Around M-dwarf Stars: Generalized Models And Strategies For Optimization

Growth and Photosynthetic Efficiency of Microalgae and Plants with Different Levels of Complexity Exposed to a Simulated M-Dwarf Starlight

The Space Weather Around The Exoplanet GJ 436 b. II. Stellar Wind-exoplanet Interactions

CO, H2O, And CH4 In The Dusty Atmosphere Of A ≤5 Myr-old Exoplanet

The CARMENES Search For Exoplanets Around M Dwarfs. Behaviour Of The Paschen Lines During Flares And Quiescence

The Role of Magma Oceans in Maintaining Surface Water on Rocky Planets Orbiting M-Dwarfs

A Young Super-Earth Orbiting Red Dwarf AU Microscopii Is Evaporating

A Whole-Earth Simulation Built To Help Find Life On Other Planets

NASA Spaceline Current Awareness List #1,223 30 October 2026 (Space Life Science Research Results)

Communicating The Uncertainty Of Extraterrestrial Life: How The News Media Portrayed The Contested Phosphine Detection On Venus

Windows of Nutrient Bioaccessibility: Phosphorus as a Key Constraint on the Chemical Potential for Life Beyond Earth

Hidden In Plain Sight In Ryugu And Meteorites