M-dwarf Archives

Shows the CH4 production rate from ecosystem 1 for the 3.8 Ga Earth (dashed) and TRAPPIST-1e (solid) case. The CH4 production rate is split between anoxic H2 (purple) and CO (grey) consumers. the total of these is also shown (green) This plot used simulations with the reduced network. -- astro-ph.EP

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

Biosignatures From Pre-oxygen Photosynthesising Life On TRAPPIST-1e

by Keith CowingApril 18, 2024April 18, 2024

In order to assess observational evidence for potential atmospheric biosignatures on exoplanets, it will be essential to test whether spectral fingerprints from multiple gases can be explained by abiotic or […]

Empirical, non-parametric radius distribution of planets hosted by late K- and early M-type dwarfs observed by Kepler and assigned ages based on rotation, corrected for detection efficiency. The black line is the total distribution (113 planets), while the red and blue lines are the distributions for the halves of the sample with rotation-based ages younger and older than the median age of 3.86 Gyr, respectively. Shaded regions denote 68% confidence interval determined from Monte Carlo sampling with replacement. The vertical magenta lines mark the location (and uncertainty) of the radius valley using Eqn. 11 in Ho & Van Eylen (2023) for the sample’s median mass of 0.59 M⊙ and median period of 7.1 days. -- astro-ph.EP

Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Stellar Cartography

The Radius Distribution Of M dwarf-hosted Planets And Its Evolution

by Keith CowingApril 18, 2024April 18, 2024

M dwarf stars are not only the most promising hosts for detection and characterization of small and potentially habitable planets, they provide leverage relative to solar-type stars to test models […]

Galactic distribution of the sample stars. The color bar means the extinction value. -- astro-ph.SR

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Space Weather & Heliophysics, Status Report

Ultraviolet And Chromospheric Activity And Habitability Of M Stars

by Keith CowingApril 4, 2024April 4, 2024

M-type stars are crucial for stellar activity studies since they cover two types of magnetic dynamos and particularly intriguing for habitability studies due to their abundance and long lifespans during […]

A comparison of simulated transmission spectra for TRAPPIST-1 e modeled with a self-consistent, Earth-like atmosphere. When self-consistent ice and water clouds are included, no significant spectroscopic changes occur to the spectrum. We see small impacts due to clouds in the relatively transparent portion of the atmosphere between 8 – 13 µm, where the clouds reduce the minimum altitude probed from 10 to 12 km. -- astro-ph.EP

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

Retrieved Atmospheres and Inferred Surface Properties for Exoplanets Using Transmission and Reflected Light Spectroscopy

by Keith CowingApril 3, 2024April 3, 2024

Future astrophysics missions will seek extraterrestrial life via transmission and direct imaging observations.

Top row: CCF between the best-fit model and the measured spectra for (a) HIP 21543, (b) HIP 94666, and (c) HIP 50319. The CCF SNR is included in the top left of the plots. The periodic oscillations in the CCF for HIP 50319 are due to residual fringing that was not fully removed in the fits, limiting us to a tentative detection on this target. Lower two rows: CHARA detection maps for HIP 21543 and HIP 50319. HIP 94666 is omitted as it was not detected by CHARA. The axes mark distance in milliarcseconds from the primary, with North up and East left. The white crosshairs denote the detected companion. Four maps are shown for HIP 21543, two for MIRC-X (d,f) and two for MYSTIC (e,g), across both nights. HIP 50319 has two maps (h,i), both from MYSTIC, one for each night. The upper left text in the CHARA maps denotes the observing night, beam combiner, and band for each plot.

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

Vortex Fiber Nulling for Exoplanet Observations: First Direct Detection of M Dwarf Companions around HIP 21543, HIP 94666, and HIP 50319

by Keith CowingMarch 27, 2024March 27, 2024

Vortex fiber nulling (VFN) is a technique for detecting and characterizing faint companions at small separations from their host star.

Top Left: The co-added sum of 15 Keck NIRC2 narrow camera images, each with an exposure time of 60 seconds. The target is indicated with a square outline. Top Right: Zoomed image of the MB07192 blended source and lens stars. The magnitude of the separation in this epoch is 29.3 ± 1.1 mas. Bottom Left: The residual image from a single-star PSF fit with DAOPHOT. A clear signal is seen due to the blended stellar profiles. Bottom Right: The residual image for a simultaneous two-star PSF fit, showing a significantly improved subtraction. The color bar represents the pixel intensity (or counts) in the bottom panel residual images. -- astro-ph.EP

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

Unveiling MOA-2007-BLG-192: An M Dwarf Hosting a Likely Super-Earth

by Keith CowingMarch 20, 2024March 20, 2024

We present an analysis of high angular resolution images of the microlensing target MOA-2007-BLG-192 using Keck adaptive optics and the Hubble Space Telescope.

Calculated dayside surface temperature matrices for some of the studied planets. Temperatures are presented in Kelvin. N = 1 was considered, since it is not expected that any of these planets have a very thick atmosphere. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Microbiology & Virology, Press Release, Proxima Centauri, Radiation, Space Weather & Heliophysics, TRAPPIST-1

How Habitable are M-dwarf Exoplanets?

by Keith CowingMarch 7, 2024March 7, 2024

How Habitable are M-dwarf Exoplanets? Modeling Surface Conditions and Exploring the Role of Melanins in the Survival of Aspergillus niger Spores Under Exoplanet-like Radiation

To better visualize the successful ground-based recovery of each transiting planet, we stack all ground-based observations, excluding those containing transits of multiple planets. Each transit center is set to 0 hours. Individual transit measurements are plotted using small filled circles with colors matching those shown for each date in Figs. 2, 3, and 4. The transits binned to 10-minute intervals are shown as white-filled black circles. The transit models are represented by black lines, with the models for each observation stacked on top of each other. -- astro-ph.EP

Astronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Status Report

Validation Of A Third Planet In The LHS 1678 System

by Keith CowingMarch 5, 2024March 5, 2024

The nearby LHS 1678 (TOI-696) system contains two confirmed planets and a wide-orbit, likely-brown-dwarf companion, which orbit an M2 dwarf with a unique evolutionary history. The host star occupies a […]

The long-term (from RECONS) and mid-term (from TESS) changes in irradiance are shown for the 46 exoplanets (excluding Earth) reported to be orbiting the 22 ATLAS stars for which we have both 0.9 m and TESS data. Irradiance changes are expressed in erg/s/cm2 , calculated for the stars using BT-Settl model stellar fluxes at the planetary orbital distances and using the variability measurements in the respective filters of observation as given in Table 1 (described in detail in §6.2). Points are colored by their reported orbital semi-major axis. A black circle denotes that the exoplanet lies in the HZ at a distance appropriate for liquid water to exist. The grey lines (solid, dashed, dot-dashed) are the 1:1, 1:2, and 2:1 comparison lines between the long-term variability and mid-term variability. -- astro-ph.SR

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

The Solar Neighborhood LI: A Variability Survey of Nearby M Dwarfs with Planets from Months to Decades with TESS and the CTIO/SMARTS 0.9 m

by Keith CowingFebruary 23, 2024

We present the optical photometric variability of 32 planet-hosting M dwarfs within 25 parsecs over timescales of months to decades. The primary goal of this project, ATLAS — A Trail […]

Sensitivity map for TIC 11893637, using the methodology described in Section 2. While this lightcurve was ultimately not included in our final analysis due to its short duty cycle, we show a comparison to Ment & Charbonneau (2023) to show consistency in completeness across methodologies. Axes drawn from Ment & Charbonneau (2023). -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Space Weather & Heliophysics, Status Report

Quantifying The Effect of Short-timescale Stellar Activity Upon Transit Detection in M Dwarfs

by Keith CowingFebruary 2, 2024February 2, 2024

M dwarf stars comprise 70-80% of the galaxy’s stars and host most of its rocky planets. They also importantly differ from Sunlike stars in that they are “active” for billions […]

M-dwarf

Biosignatures From Pre-oxygen Photosynthesising Life On TRAPPIST-1e

The Radius Distribution Of M dwarf-hosted Planets And Its Evolution

Ultraviolet And Chromospheric Activity And Habitability Of M Stars

Retrieved Atmospheres and Inferred Surface Properties for Exoplanets Using Transmission and Reflected Light Spectroscopy

Vortex Fiber Nulling for Exoplanet Observations: First Direct Detection of M Dwarf Companions around HIP 21543, HIP 94666, and HIP 50319

Unveiling MOA-2007-BLG-192: An M Dwarf Hosting a Likely Super-Earth

How Habitable are M-dwarf Exoplanets?

Validation Of A Third Planet In The LHS 1678 System

The Solar Neighborhood LI: A Variability Survey of Nearby M Dwarfs with Planets from Months to Decades with TESS and the CTIO/SMARTS 0.9 m

Quantifying The Effect of Short-timescale Stellar Activity Upon Transit Detection in M Dwarfs

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