M-dwarf Archives

Direct imaging visibility of the five planets in the HD 134606 system. Left panel: top down view of the system with CHZ (bright green) and OHZ (dark green) overlaid. Right panel: sky projected view of the system with 60◦ orbital inclination. IWA and IWA0.5 are represented by the bright and dark shaded disks, respectively. Orbits are color coded if they are above the 1×10−10 flux ratio with 60◦ inclination. Inner four planetary orbits are too compact to be shown with detail on this scale. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Status Report

Revised Architecture And Two New Super-Earths In The HD 134606 Planetary System

by Keith CowingFebruary 1, 2024February 1, 2024

Multi-planet systems exhibit a diversity of architectures that diverge from the solar system and contribute to the topic of exoplanet demographics. Radial velocity (RV) surveys form a crucial component of […]

Tpfplotter (Aller et al. 2020) target pixel file (TPF) images of Wolf 327 for sectors 21 and 48. The red squares correspond to the TESS aperture used to compute the photometry, the size of the red circles represent the Gaia DR3 (Gaia Collaboration et al. 2023) magnitudes of the stars, and the gray arrows shows the Gaia DR3 proper motion directions of each star inside the field of view. Wolf 327b is positioned at the center (star 1), star 7 (TIC 4918919) is a known eclipsing binary. -- astro-ph.EP

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

Wolf 327b: A New Member Of The Pack Of Ultra-short-period Super-Earths Around M Dwarfs

by Keith CowingJanuary 24, 2024January 23, 2024

Planets with orbital periods shorter than 1 day are rare and have formation histories that are not completely understood. Small (Rp<2R⊕) ultra-short-period (USP) planets are highly irradiated, probably have rocky […]

Location of FRL-specific residues in FRL-PSI. The structure of FRL-PSI from F. thermalis PCC 7521 is shown. This figure corresponds to the multiple sequence alignment shown in Supplementary Figure 6. Yellow spheres represent residues that are FRL-specific and are conserved in the ancestral sequence. Green spheres represent FRL-specific residues that are not conserved in the ancestral sequence. Chl f-binding sites that are conserved among the current FRL-PSI structures are shown with a pink glow and are labeled with bold font on each of the surface views (e.g., site B30). Chl f-binding sites that are observed to be species-specific based on the current structures are labeled with regular font (e.g., site B19). In the top left panel, the FRL-specific subunits are additionally labeled. The four clusters of FRL-specific residues are labeled c1 through c4. -- Frontiers/Queen Mary University of London

Habitable Zones, Imaging & Spectroscopy, Origin & Evolution of Life, Plant Biology, Press Release, Proxima Centauri, Space Agriculture, TRAPPIST-1

A Spectrum Of Possibilities: Insights Into The Evolution Of Far-red Light Photosynthesis

by Keith CowingNovember 28, 2023November 28, 2023

A collaborative study led by Dr. Christopher Gisriel at Yale University and Dr. Tanai Cardona at Queen Mary University of London, published in Frontiers in Plant Science, offers new insight […]

Boundaries of the Habitable Zone under various climate and atmospheric models as a function of radiative flux received from the host star, relative to Earth. Dashed lines represent the extended boundaries due to subglacial liquid water suggested in this work: blue for the inner HZ boundary (nightside ice evaporates due to heat transport, the percentage marks the global transport parameter f) and violet for the outer one (Martian polar lakes). Solid green lines and green shading denote the conservative HZ boundaries: inner one (moist greenhouse) and outer one (maximum CO2 greenhouse), calculated using the 1-D climate model. Also marked is the recent Venus boundary (dashed green line). The orange curve marks the tidal locking radius. Circles denote the terrestrial planets in the solar system and a few Earth-sized exoplanets orbiting M-dwarf stars. -- Hebrew University of Jerusalem

Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Press Release, Water/Hycean Worlds & Oceanography

Extended Habitability Of Exoplanets Due To Subglacial Water

by Keith CowingNovember 10, 2023November 10, 2023

Professor Amri Wandel, from Hebrew University of Jerusalem, has unveiled research that promises to redefine our comprehension of habitable exoplanets. In a recent study published in the Astronomical Journal, Professor […]

TESS observations of TOI-904. Panel (a): Raw observations of each TESS sector, with 2-minute data shown in light grey and 10-minute binned data shown in dark grey. We show the Tukey biweight trend calculated with the wotan (Hippke et al. 2019) library of the variability is shown in dark blue. Each planet transit is denoted by an arrow at the bottom of the graph, with blue denoting transits of TOI-904 b and gold denoting transits TOI-904 c. Panel (b): TESS data detrended by the same fit, with each transit high-lighted in the same color as the arrows in the previous figure. Panel (c): The phase folded light curves of transits of TOI-904 b with the transit fit including a shaded region denoting 1σ uncertainty. Panel (d): The phase-folded light curves of TOI-904 c with the transit fit including a shaded region denoting 1σ uncertainty. -- astro-ph.EP

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

Separated Twins Or Just Siblings? A Multi-planet System Around An M Dwarf Including A Cool sub-Neptune

by Keith CowingOctober 24, 2023October 24, 2023

We report the discovery of two TESS sub-Neptunes orbiting the early M dwarf TOI-904 (TIC 261257684). Both exoplanets, TOI-904 b and c, were initially observed in TESS sector 12 with […]

Comparison between the observed data (red) and the model (blue) with Teff , log g , and metallicity of 3200 K, 5.0 dex and −0.5 dex, respectively. The Top panel shows some alpha elements (e.g., Ti I and Mg I) as well as several isolated and blended Fe I lines. The middle panel shows the Na I doublet frequently used in several studies as metallicity indicators of M dwarfs. The bottom panel shows numerous absorption features of the CO band head starting around 2.29 µm (red dashed lines). -- astro-ph.EP

Astronomy & Telescopes, Barnard's Star, Habitable Zones, Imaging & Spectroscopy, Status Report

Comprehensive High-resolution Chemical Spectroscopy of Barnard’s Star with SPIRou

by Keith CowingOctober 19, 2023October 1, 2024

Determination of fundamental parameters of stars impacts all fields of astrophysics, from galaxy evolution to constraining the internal structure of exoplanets.

Because of Kepler ’s poor sensitivity to habitable zone planets (around any star), the current sample does not offer evidence to support M dwarfs hosting more Earth-sized planets than FGK stars at habitable zone instellations. Top: The number of Earth-sized ([0.5, 1.5] R⊕) Kepler planet candidates orbiting M (solid blue), K (dashed orange), G (dot-dashed green) or F (dotted red) dwarf stars as a function of instellation. The shaded grey region denotes the regime where there are no detections of Earth-sized planets around F type stars, such that FGKM comparisons require models and/or extrapolations. Bottom: Earth-sized planet occurrence rates calculated via the reliability-weighted inverse detection efficiency method (Equation 4) over a continuum of habitable zone-width instellation bins. Vertical black dashed line represents the approximate point where the Petigura et al. (2022) occurrence distribution plateaus for [0.5, 0.7] M⊕ stars, indicating the regime where comparisons between spectral types would not be affected by differences in the break points of their power law distributions. -- astro-ph.SR

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

No Evidence For More Earth-sized Planets In The Habitable Zone of Kepler’s M Versus FGK Stars

by Keith CowingOctober 19, 2023October 19, 2023

Reliable detections of Earth-sized planets in the habitable zone remain elusive in the Kepler sample, even for M dwarfs. The Kepler sample was once thought to contain a considerable number […]

Mass-radius diagram for TOI-1801 b, together with all known exoplanets (grey dots) with a precision better than 8% in radius (through transit) and 20% in mass (from RV). The population of young transiting exoplanets (< 900 Myr) with measured masses is plotted as coloured dots, according to their ages. The uncertainties on TOI-1801 b are shown as coloured shaded regions with 1, 2, and 3σ levels of confidence. In the left panel, the iso-density lines are displayed as dashed grey lines. In the remaining panels where the population of exoplanets is plotted along with TOI-1801 b, coloured lines indicate different composition models without gas (middle panel) and with a gas envelope (right panel) from Zeng et al. (2019). In the right panel, the solid and dotted lines show the models with temperatures of 300 K and 500 K, respectively, of the corresponding specific entropy at 100 bar level in the gas envelope. The Earth and Neptune are also depicted as reference. We include B22 and M22 as references because different results have been published for the same planet, and this refers to Barragán et al. (2022) and El Mufti et al. (2023), respectively. -- astro-ph.EP

Exoplanets, -moons, -comets, Habitable Zones, Status Report

TOI-1801 b: A Temperate Mini-Neptune Around A Young M0.5 Dwarf

by Keith CowingOctober 17, 2023October 17, 2023

We report the discovery, mass, and radius determination of TOI-1801 b, a temperate mini-Neptune around a young M dwarf. TOI-1801 b was observed in TESS sectors 22 and 49, and […]

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Status Report

Extended Habitability Of Exoplanets Due To Subglacial Water

by Keith CowingOctober 5, 2023October 4, 2023

Considering subglacial liquid water, a significant extension of the classical Habitable Zone is obtained. Elaborating on the model of Wandel (2023) it is shown how an atmosphere and liquid water […]

Calculated obliquity ranges for each planet, as a function of orbital semi-major axis. The obliquity range is calculated using only the |g| values for interactions of adjacent pairs of planets (e.g. TRAPPIST-1 c with TRAPPIST-1 b or with TRAPPIST-1 d) and the median obliquity for each range is plotted as a point on the range line. The planets with no possible obliquity for a given value of |g| are plotted as a dashed line. The value for Earth’s obliquity is also shown as a reference. There is a wide range of obliquity values possible for planets 0.01 − 0.4 AU from their host star. Beyond roughly 0.4 AU, non-zero obliquity due to capture in Cassini State 2 is no longer excited. -- astro-ph.EP

Exoplanets, -moons, -comets, Habitable Zones, Status Report

Plausibility Of Capture Into High-Obliquity States For Exoplanets In The M Dwarf Habitable Zone

by Keith CowingOctober 5, 2023October 4, 2023

For temperate exoplanets orbiting M dwarf hosts, the proximity of the habitable zone to the star necessitates careful consideration of tidal effects.

M-dwarf

Revised Architecture And Two New Super-Earths In The HD 134606 Planetary System

Wolf 327b: A New Member Of The Pack Of Ultra-short-period Super-Earths Around M Dwarfs

A Spectrum Of Possibilities: Insights Into The Evolution Of Far-red Light Photosynthesis

Extended Habitability Of Exoplanets Due To Subglacial Water

Separated Twins Or Just Siblings? A Multi-planet System Around An M Dwarf Including A Cool sub-Neptune

Comprehensive High-resolution Chemical Spectroscopy of Barnard’s Star with SPIRou

No Evidence For More Earth-sized Planets In The Habitable Zone of Kepler’s M Versus FGK Stars

TOI-1801 b: A Temperate Mini-Neptune Around A Young M0.5 Dwarf

Extended Habitability Of Exoplanets Due To Subglacial Water

Plausibility Of Capture Into High-Obliquity States For Exoplanets In The M Dwarf Habitable Zone

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