M-dwarf Archives

The transmission spectrum of TOI-732 c in the NIR.

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

A JWST Transmission Spectrum Of The Temperate Sub-Neptune TOI-732 c

by Keith CowingDecember 25, 2025December 25, 2025

In recent years, JWST has facilitated detections of carbon-bearing molecules in the atmospheres of temperate sub-Neptunes orbiting M dwarfs, ushering in a new era in the characterization of this intriguing […]

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

JWST NIRSpec Finds No Clear Signs Of An Atmosphere On TOI-1685 b

by Keith CowingDecember 18, 2025December 18, 2025

Determining the prevalence of atmospheres on terrestrial planets is a core objective in exoplanetary science. While M dwarf systems offer a promising opportunity, conclusive observations of terrestrial atmospheres have remained […]

Multi-color ground-based light curves for our five targets. Data points represent 10-minute binned photometry, with light curves obtained using identical filters and exposure times phase-folded together. Black curves show the median transit model derived from the posterior distribution, with colored shading indicating the 68% confidence intervals. Blue curves represent the nominal TESS light curve model projected into the corresponding ground-based filters. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

From Earths To Super-Earths: Five New Small Planets Transiting M Dwarf Stars

by Keith CowingDecember 18, 2025December 18, 2025

Earth-sized planets transiting M dwarf stars present one of the best opportunities with current facilities for studying the atmospheric and bulk compositions of terrestrial worlds.

Normalized torques as a function of planetary mass and semimajor axis, assuming circular and coplanar orbits. The different migration regimes are indicated, separating inward from outward migration. The mass required to open a gap in the disk (dashed white line), the planet-to-star mass ratio (q) of 0.002, and the gas depth criterion K = 104 are over-plotted (dashed black lines). -- astro-ph.EP

Astrogeology, Exoplanets, -moons, -comets, Gas Giants, Status Report

Formation Of Cold Giant Planets Around Late M Dwarfs Via Core Accretion And The Fate Of Inner Rocky Worlds

by Keith CowingDecember 11, 2025December 10, 2025

Modeling the formation of cold giant planets around M dwarfs is difficult because their disks may not contain enough solids to form massive cores and because forming giants are expected […]

TESS PDC-SAP flux measurements extracted from the 2-min cadence data of TOI-7166. The target was observed in sector 82. The blue points show the 2-min data, and the red points show the 20-min binned data. The transit locations of TOI-7166 b are shown with black arrows and zoom boxes. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

TOI-7166 b: A Habitable Zone Mini-Neptune Planet Around A Nearby Low-mass Star

by Keith CowingDecember 9, 2025January 15, 2026

We present the discovery and validation of TOI-7166b, a 2.01+/-0.05R_Earth planet orbiting a nearby low-mass star.

Surface flux density observed and modelled. The m2F12-37-2.5 (dark green) and cF13-500-3 (light green) stellar atmosphere models are plotted at coefficients Xˆ 1=1 and Xˆ 2 = 1 (the theoretical assumption of the entire stellar surface exhibiting flaring activity). For AU Mic during a flare, the red solid and orange dashed lines show the fitted model spectrum at flare maximum using coefficients from the example fit (the flare data are stated in Table A.1 in Appendix A.2). The inverse H6 model at flare maximum, pre-flare and the ‘fiducial flare’ model from Loyd et al. (2018a) with a comparable ED is plotted as blue dash-dotted, light blue dashed, and purple dashed lines, respectively. Blackbody curves for 3850 K, 6000 K, 8000 K, and 10,000 K are included in black solid, dotted, dash-dotted and dashed lines. The panchromatic AU Mic flux from Feinstein et al. (2022) is plotted in light grey. Insets highlight the FUV (lower left) and TESS (lower right) wavelength ranges. -- astro-ph.SR

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Press Release, Radiation, Space Weather & Heliophysics

Young M Dwarfs Flare Activity Model: Towards Better Exoplanetary Atmospheric Characterisation

by Keith CowingDecember 8, 2025December 8, 2025

Context. Stellar flares can significantly influence the atmospheres and habitability of orbiting exoplanets, especially around young and active M dwarfs. Understanding the temporally and spectrally resolved activity of such stars […]

The recovery probability (successful AltaiPony detection) of injected flares in the TESS light curves of GJ 1132 (top left), TOI-2445 (top right), TRAPPIST-1 (bottom left) and the average of recovered flare durations (in minutes) and flare SNR for all three stars (bottom right). From tests on approximately 6500 injected flares per star, these heatmaps show the probability that AltaiPony detects a flare of a given duration and amplitude relative to the light curve noise. The color of each bin represents the recovery probability from 0 to 1, with black contours indicating the approximate curves of of 25%, 50%, 75% and 90% recovery probability. Although the noise levels within each stars’ light curve varies greatly, we see consistent recovery probability of flares. -- astro-ph.SR

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Space Weather & Heliophysics, Status Report, Stellar Cartography

Stellar Flares In The TESS Light Curves Of Planet-hosting M dwarfs

by Keith CowingNovember 20, 2025November 20, 2025

M dwarfs are magnetically active stars that frequently produce flares, which have implications for both stellar evolution and exoplanet studies.

The mass and radius of our two models for GJ 12 b (circular and eccentric orbits) compared to various composition models from L. Zeng et al. (2019), as well as a steam atmosphere model from M. Turbet et al. (2020) and an H/He atmospheric model from M. C. Nixon & N. Madhusudhan (2021) and M. C. Nixon et al. (2024). The star corresponding to the eccentric-orbit model has been shifted slightly upward so that the errors of the two points are distinguishable. We note that the 50% water model, which is from L. Zeng et al. (2019), assumes a planet temperature of 300 K, which is very close to the actual equilibrium temperature of this planet. -- The Astronomical Journal

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

An Earthlike Density For The Temperate Earth-sized Planet GJ 12 b

by Keith CowingNovember 20, 2025November 19, 2025

While JWST has provided us with the opportunity to probe the atmospheres of potentially habitable planets, observations of the TRAPPIST-1 system have shown us that active stars severely complicate efforts […]

Overview of the atmosphere-interior exchange model we use for this study including the various geological processes that we simulate and the various parameters we consider in this model. The carbon cycle is the major overarching process added to this model, which is a negative feedback cycle that regulates the temperature of the planet over geologic timescales, which is crucial for studying habitability. -- astro-ph.EP

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

The Effect of Oxygen Fugacity and Initial Volatile Abundance on the Atmospheres of the TRAPPIST-1 Planets

by Keith CowingNovember 17, 2025November 17, 2025

The TRAPPIST-1 planets have become prime targets for studying the atmospheric and geophysical properties of planets around M-dwarf stars.

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

Tidally Torn: Why the Most Common Stars May Lack Large, Habitable-Zone Moons

by Keith CowingNovember 9, 2025

Earth-like planets in the habitable zone (HZ) of M-dwarfs have recently been targeted in the search for exomoons.

M-dwarf

A JWST Transmission Spectrum Of The Temperate Sub-Neptune TOI-732 c

JWST NIRSpec Finds No Clear Signs Of An Atmosphere On TOI-1685 b

From Earths To Super-Earths: Five New Small Planets Transiting M Dwarf Stars

Formation Of Cold Giant Planets Around Late M Dwarfs Via Core Accretion And The Fate Of Inner Rocky Worlds

TOI-7166 b: A Habitable Zone Mini-Neptune Planet Around A Nearby Low-mass Star

Young M Dwarfs Flare Activity Model: Towards Better Exoplanetary Atmospheric Characterisation

Stellar Flares In The TESS Light Curves Of Planet-hosting M dwarfs

An Earthlike Density For The Temperate Earth-sized Planet GJ 12 b

The Effect of Oxygen Fugacity and Initial Volatile Abundance on the Atmospheres of the TRAPPIST-1 Planets

Tidally Torn: Why the Most Common Stars May Lack Large, Habitable-Zone Moons

Ancient Layers On Mars Exposed By A Crater Within A Crater In Terra Sirenum

Send Your Name to Titan Aboard NASA’s Dragonfly Astrobiology Mission

Reconciling Giant Impacts with the Radius Valley: The Role of Silicate-Hydrogen Miscibility for Sub-Neptunes

Comprehensive Visible and Near-infrared Keck and Gemini Monitoring and Characterization of Interstellar Comet 3I/ATLAS during its Encounter with the Solar System

ExoVetter and a TESS Exoplanet Transit Search of Kepler Stars as Ground Truth