M-dwarf Archives

Core–mantle partition coefficient of oxygen as a function of pressure and temperature. Left: Experimental data for metal–silicate partitioning of O obtained at high pressures up to 104 GPa. Horizontal dashed line located at DO=0.83 indicates full oxidation of the core (see the main text), and therefore distinguishes ‘terrestrial’ from ‘coreless’ planets. It is clear that, within the investigated pressure range, DO asymptotically approaches the dashed line, but never reaches the core-free regime, albeit higher pressures and temperatures promote the sequestration of O into the metallic core, i.e. larger DO. Right: The same dataset for O partitioning plotted as a function of reciprocal temperature. Dashed lines are fitted results (Eq. 7) showing the dependence of O partitioning on temperature at a given pressure or vice versa. -- astro-ph.EP

Astrogeology, Exoplanets, -moons, -comets, Status Report, TRAPPIST-1

Limits On Forming Coreless Terrestrial Worlds In The TRAPPIST-1 System

by Keith CowingNovember 4, 2025November 4, 2025

With seven temperate Earth-sized planets revolving around an ultracool red dwarf, the nearby TRAPPIST-1 system offers a unique opportunity to verify models of exoplanet composition, differentiation, and interior structure.

Illustration of the behaviour of the CARMENES visible channel CRX for the mid-M dwarf EV Lac. Top Left: Variation of RV as a function of wavelength (spacing is logarithmic). The CRX-index is the slope of RV vs log(λ) for each spectrum. A total of 10 CARMENES spectra are shown covering approximately one stellar rotation. The upper and lower boundaries are the fits to the most positive and negative RV values. Top right: The CRX-gradient, illustrating the CRX-index as a function of mean RV. Bottom Left and Bottom Right: CRX vs rotation phase and RV vs rotation phase illustrating the anti-correlation of CRX-index (i.e. the negative CRX-gradient shown in the top right panel). The plotted points in each panel are colour coded according to stellar rotation phase. -- astro-ph.EP

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

The CARMENES Search For Exoplanets Around M dwarfs: Understanding The Wavelength Dependence Of Radial Velocity Measurements

by Keith CowingNovember 3, 2025November 3, 2025

Context. Current exoplanet surveys are focused on detecting small exoplanets orbiting in the liquid-water habitable zones of their host stars. Despite the recent significant advancements in instrumental developments, the current […]

Schematic of episodic atmospheric collapse and regeneration through impacts for a tidally locked planet. A) The planet has a volatile rich atmosphere which redistributes heat from the day- to the nightside. B) Atmospheric escape thins the atmosphere, heat redistribution becomes less efficient, nightside temperatures drop. C) Nightside temperatures have reached the volatile condensation temperature, the atmosphere collapses. D) Volatiles outgassed through volcanism or magma ocean pockets accumulate on the nightside as ice. E) An impactor hits the nightside and vaporises ice and rock. Hot vapour, ejecta, and silicate rain further vaporise the nightside ice sheets (see Section 2.2 for details). An atmosphere is regenerated. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Extinction events, Impact events, Status Report

Atmospheric Collapse And re-inflation Through Impacts For Terrestrial Planets Around M Dwarfs

by Keith CowingOctober 31, 2025October 31, 2025

Detection of an atmosphere around a terrestrial exoplanet will be a major milestone in the field, but our observational capacities are biased towards to tidally locked, close-in planets orbiting M-dwarf […]

This illustration shows a red dwarf star orbited by a hypothetical exoplanet. Red dwarfs tend to be magnetically active, displaying gigantic arcing prominences and a wealth of dark sunspots. Red dwarfs also erupt with intense flares that could strip a nearby planet’s atmosphere. -- NASA

AI - Data - Apps - Cybernetics, Astronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Press Release, Radiation, Space Weather & Heliophysics

The Largest Ground-based Catalogue Of M-dwarf Flares

by Keith CowingOctober 30, 2025October 30, 2025

We present the largest ground-based catalogue of M-dwarf flares to date, comprising 1,229 time-resolved events identified in Zwicky Transient Facility Data Release 17.

The magnetopause standoff distance of a planet orbiting our stellar sample. The theoretical decay of the Parker model (blue) and that measured in the solar system (red) are used in the estimations for Case 1 (left panels) and for Case 3, fast wind (right panels). In the upper (bottom) panels the planet is orbiting the outer (inner) radius of the HZ. The gray dashed line represents Earth’s early magnetosphere. The results of Vidotto et al. (2013) were added for comparison. -- astro-ph.SR

Habitable Zones, Imaging & Spectroscopy, Origin & Evolution of Life, Radiation, Space Weather & Heliophysics, Status Report

The Impact Of Stellar Winds And Tidal Locking Effects On The Habitability Of Earth-like Exoplanets Around M Dwarf Stars

by Keith CowingOctober 28, 2025October 28, 2025

We present an assessment of the effects of stellar wind magnetic and mechanical components on the habitability of Earth-like exoplanets orbiting the inner and outer radii of the habitable zone […]

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. -- MRAS

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

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

by Keith CowingOctober 27, 2025October 27, 2025

We present the discovery and validation of TOI-7166 b, a 2.01 ± 0.05 R⊕ planet orbiting a nearby low-mass star.

Sketch of the protoplanetary disc structure. In the inner region of the disc, where the gas is sufficiently hot (𝑇c > 𝑇crit), the gas is ionized and well-coupled to the magnetic field, allowing the MRI to operate effectively. At larger radii, where the temperature is lower, the MRI is suppressed due to insufficient ionization, leading to the formation of a layered disc structure. MRI turbulence occurs in the thin surface layers ionized by cosmic rays or X-rays (with Σ = Σcrit), while the cold mid-plane forms a “dead zone” where the MRI is inactive. In the outer parts of the disc, where the surface density is low enough (Σ < Σcrit) for cosmic rays to penetrate to the mid-plane, the disc becomes fully MRI-active again. The outer parts of the dead zone may be heated by self-gravity if sufficient material builds up. The shaded regions in the figure indicate two possible icy zones within the disc: (1) an outer icy region far from the star and (2) an inner icy region located within the dead zone, closer to the star. -- astro-ph.EP

Exoplanets, -moons, -comets, Press Release, Stellar Cartography

Formation Of Super-Earths Around Low-mass Stars: Evolution Of An Icy Dead Zone

by Keith CowingOctober 21, 2025

Exoplanet observations show that close-in super-Earths are more common around M-dwarfs than around solar mass stars.

Alien Wind Power - Grok via Astrobiology.com

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Intelligence & Language, SETI & Technosignatures, Status Report

Wind Power As A Technosignature On M-dwarf Planets

by Keith CowingOctober 20, 2025October 20, 2025

We suggest that the large-scale deployment of wind turbines on an M-dwarf planet could produce observable technosignatures.

Upper panel: UV flux reaching the surface of the planet TOI-700 d for an Archean atmosphere, depicted in purple (fUV=1) and red (fUV=10), and a modern Earth-like atmosphere, in green (fUV=1) and blue (fUV=10). The different surface pressures, namely 4.0, 2.0, 1.0, and 0.5, are represented by tones gradually shifting towards lighter shades, indicating a transition from higher to lower pressure. The solar flux reaching both Earth’s exosphere and surface is depicted by solid black line and dashed black line, respectively, primarily for the purpose of comparison. Lower panel: a blowup of the flux scale depicted on the upper panel. -- astro-ph.EP

Analog Studies, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report

Evaluating Habitability and Biosignature Detection on TOI-700 d: The Role of UV Environment and Atmospheric Pressure

by Keith CowingOctober 17, 2025October 17, 2025

M dwarfs have long been prime targets in the search for habitable exoplanets, owing to their abundance in the galaxy and the relative ease of detecting Earth-sized worlds within their […]

Snapshots of VGS-calculated surface water mass (in units of Earth’s ocean mass) for TRAPPIST-1 analogs, shown as a function of total planet mass (M⊕) and final orbital distance (AU). Panel (a) depict planets at the halfway point of accretion (i.e., when the protoplanet reaches half its final mass), while panels (b) show the final planet properties. Measured properties of the TRAPPIST-1 planets are indicated by black circles (Agol et al. 2021). At mid-assembly, most inner planets are water-poor due to early impact-driven loss and higher irradiation. By the end of accretion, increased volatile delivery events from more water-rich materials and reduced erosion allow many planets, particularly beyond ∼0.03 AU,to accumulate and preserve large water reservoirs, leading to the strong radial gradient in water content. -- astro-ph.EP

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

Born Dry or Born Wet? A Palette of Water Growth Histories in TRAPPIST-1 Analogs and Compact Planetary Systems

by Keith CowingOctober 15, 2025October 15, 2025

It is still unclear whether exoplanets in compact multiplanet systems such as TRAPPIST-1 are able to accrete large quantities of volatiles, grow to sufficient mass, and maintain robust atmospheres and […]

M-dwarf

Limits On Forming Coreless Terrestrial Worlds In The TRAPPIST-1 System

The CARMENES Search For Exoplanets Around M dwarfs: Understanding The Wavelength Dependence Of Radial Velocity Measurements

Atmospheric Collapse And re-inflation Through Impacts For Terrestrial Planets Around M Dwarfs

The Largest Ground-based Catalogue Of M-dwarf Flares

The Impact Of Stellar Winds And Tidal Locking Effects On The Habitability Of Earth-like Exoplanets Around M Dwarf Stars

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

Formation Of Super-Earths Around Low-mass Stars: Evolution Of An Icy Dead Zone

Wind Power As A Technosignature On M-dwarf Planets

Evaluating Habitability and Biosignature Detection on TOI-700 d: The Role of UV Environment and Atmospheric Pressure

Born Dry or Born Wet? A Palette of Water Growth Histories in TRAPPIST-1 Analogs and Compact Planetary Systems

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