M-dwarf Archives - Page 9 of 30 - Astrobiology

Distributions of nominal and median encounter distances denc and encounter speeds venc for encounters with each 95% quantile of denc below 1.5 pc. The left panel represents the nominal values of denc and vnom enc . The right panel represents median values of dmedenc and v medenc. Error bars indicate 5% and 95% quantiles of denc and venc in MC results. The color bar is based on Equation 3 using the median of g. -- astro-ph.SR

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

Search For Past Stellar Encounters And The Origin Of 3I/ATLAS

by Keith CowingSeptember 8, 2025September 8, 2025

3I/ATLAS, the third discovered interstellar object, has a heliocentric speed of 58 km/s and exhibits cometary activity.

Distribution of the derived planetary radii as a function of insolation, along with the associated KDE. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Status Report, Stellar Cartography

An Analysis Of The Radius Gap In A Sample Of Kepler, K2 And TESS Exoplanets Orbiting M Dwarf Stars

by Keith CowingSeptember 3, 2025

Planetary radii are derived for 218 exoplanets orbiting 161 M dwarf stars. Stellar radii are based on an analysis of APOGEE high-resolution near-IR spectra for a subsample of the M-dwarfs; […]

Possible interior compositions of 55 Cnc e. Compositions consistent within the 1σ, 2σ, and 3σ M-R uncertainties are shown in orange, dark teal, and light teal, respectively. The red dashed and solid lines show xcarbon = 12 wt% and 24 wt%, respectively, the upper bounds of xcarbon assuming no volatile loss (E. A. Bergin et al. 2023). The blue curve shows interior solution from N. Madhusudhan et al. (2012), to the right of which are allowed values (1σ uncertainty). Ternary diagrams are shown for two radius assumptions: (a) visible radius, 2.04 ± 0.15 R⊕, and (b) gray radius, 2.20 ± 0.12 R⊕, following N. Madhusudhan et al. (2012). Our interior models with updated carbon and SiC EOSs are consistent with earlier studies. -- astro-ph.EP

Astrochemistry, Astrogeology, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release

Carbon-rich Sub-Neptune Interiors Are Compatible With JWST Observations

by Keith CowingAugust 22, 2025

Many possible interior compositions exist for sub-Neptunes: ice-poor, ice-rich, and water-dominated interiors can all match the measured masses and radii.

A single MIRI imaging integration of LTT 3780 b, taken from Observation 15, cut from 90 to 165 pixels in each direction of the whole frame. Shown in red is the aperture radius used for optimal extraction (30 pixels), and in grey dashed is the annulus used for background subtraction (31- 35 pixels). -- astro-ph.EP

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

Hot Rocks Survey IV: Emission From LTT 3780 b Is Consistent With A Bare Rock

by Keith CowingAugust 21, 2025August 21, 2025

It is an open question whether small planets around M dwarfs are able to maintain atmospheres. The Hot Rocks Survey aims to address this question by observing 9 rocky exoplanets […]

Cosmic Shoreline for all known planetary systems orbiting M-dwarf-type stars. The black dashed-dotted line is our newly proposed Empirical Cosmic Shoreline (ECS), same as in Figure 1. The gray points mark the systems whose atmospheres have not been studied; the orange ones mark the planets with reported strong non-detections; and the green ones mark the planets with a (tentative) atmosphere detection. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Status Report, Stellar Cartography

An Empirical Determination Of The Cosmic Shoreline

by Keith CowingAugust 19, 2025August 19, 2025

The Cosmic Shoreline concept was introduced as a way to separate planets with and without atmosphere, based on the relationship between the cumulative instellation and the escape velocity observed in […]

Retrieval results for GJ 1132 b. Top panels: comparison between the retrieved transmission spectra for the FIREFLy reduction with all four visits (left) and for three visits with Visit 1 excluded (right). Three POSEIDON retrieval models are shown: (i) an atmosphere (grey), (ii) stellar contamination (orange), and (iii) a flat line (purple). The corresponding median retrieved spectra (solid lines) and 1σ and 2σ model confidence intervals (dark and light contours) are overlaid. Labels indicate H2O and CO2 absorption bands (neither are detected, but CO2 is allowed by FIREFLy). Bottom panels: atmosphere posterior histograms for the three data reductions: FIREFLy (grey), Eureka! (pink), and ExoTiC-JEDI (cyan). The 4-visit combined analysis weakly favors a thin H2O-rich atmosphere (driven by a short-wavelength slope), but this solution is not favored when Visit 1 is excluded. -- astro-ph.EP

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

Additional JWST/NIRSpec Transits Of The Rocky M Dwarf Exoplanet GJ 1132 b Reveal a Featureless Spectrum

by Keith CowingAugust 16, 2025September 18, 2025

As an archetypal M-dwarf rocky exoplanet, GJ 1132 b has a varied history of atmospheric measurements. At 1.13 R⊕, 1.66 M⊕, and 580 K, it orbits a bright, slowly rotating […]

The radial gas temperature maps of planets from the 3D AFGKM ExoRad with a global temperature, Tglobal of 800K (left), 1600K (center) and 2400K (right) that orbit different host stars (top to bottom: A, G, M). The (Tgas, pgas)-maps gas are shown as equatorial slice plots. -- astro-ph.EP

AI - Data - Apps - Cybernetics, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Status Report

Accelerating Exoplanet Climate Modelling: A Machine Learning Approach To Complement 3D GCM Grid Simulations

by Keith CowingAugust 15, 2025August 15, 2025

With the development of ever-improving telescopes capable of observing exoplanet atmospheres in greater detail and number, there is a growing demand for enhanced 3D climate models to support and help […]

This artist’s concept depicts planet TRAPPIST-1 d passing in front of its turbulent star, with other members of the closely packed system shown in the background. Credit: NASA, ESA, CSA, J. Olmsted (STScI)

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

Webb Narrows Atmospheric Possibilities For Earth-sized Exoplanet TRAPPIST-1 d

by Keith CowingAugust 13, 2025August 13, 2025

The exoplanet TRAPPIST-1 d intrigues astronomers looking for possibly habitable worlds beyond our solar system because it is similar in size to Earth, rocky, and resides in an area around […]

Joint posterior constraints on the surface partial pressure of key atmospheric absorbers for atmospheric scenarios similar to solar system terrestrials, with N2 as the background gas. The color shadings correspond to the posterior probability mass, and the contours highlight the 68% and 95% confidence regions from the joint retrieval in each case. The absorber in the N2-background atmosphere is labeled in the top right corner of each panel. The dashed-dotted, dashed, and solid sienna lines correspond to an atmospheric surface pressure of 0.1, 1, and 10 bar. We illustrate where typical models of Archean Earth (AE), Modern Earth (ME), and compositions for Titan (T), early Mars (eMa), Mars (Ma), and Venus (V; Encrenaz & Coustenis 2018) approximately lie relative to our constraints for TRAPPIST-1 d. Star markers correspond to specific cloudy cases, where the planet is modeled as either cloudy or cloud-free (for Titan, Modern Earth, and Venus). For the N2-H2O case, we show as a black dotted line the limit of pressures that would be cut off by refraction in a 11 bar atmosphere (10 bar H2O+1 bar N2). For thinner atmospheres, the impact of refraction on atmosphere detectability is even weaker. -- astro-ph.EP

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

Strict Limits On Potential Secondary Atmospheres On The Temperate Rocky Exo-Earth TRAPPIST-1 d

by Keith CowingAugust 13, 2025August 13, 2025

The nearby TRAPPIST-1 system, with its seven small rocky planets orbiting a late-type M8 star, offers an unprecedented opportunity to search for secondary atmospheres on temperate terrestrial worlds.

Planet occurrence rates as a function of stellar temperature for short-period (P = 1 − 40 days) super-Earths (green squares) and sub-Neptunes (blue circles). A power law was fit to the super-Earths, and a double broken power law was fit to the sub-Neptunes, showing two breaks: TBr,1 = 3750+153 −97 K and TBr,2 = 5758+94 −145 K. The short-period sub-Neptunes peak around a host type of M0.5 V, then decrease in planet occurrence toward cooler M dwarfs. G and K-type stars have comparable rates of short-period super-Earths and sub-Neptunes. Another noticeable decrease in sub-Neptunes happens for host stars hotter than the Sun. Short-period super-Earths increase in occurrence toward cooler stars, with no discernible peak in the host star temperatures for which we have data from Kepler and K2. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Status Report, Stellar Cartography

Scaling K2 VIII: Short-Period Sub-Neptune Occurrence Rates Peak Around Early-Type M Dwarfs

by Keith CowingAugust 13, 2025August 13, 2025

We uniformly combined data from the NASA Kepler and K2 missions to compute planet occurrence rates across the entire FGK and M dwarf stellar range.