Stellar Cartography Archives

Left: HZ and planetary orbits in the HD 20794 system, where the orbits are labeled by planet designation. The scale of the figure is 2.9 AU along each side. Right: Variation in incident flux received by HD 20794 d during one complete orbit. For both panels, the extent of the HZ is shown in green, where light green and dark green indicate the CHZ and OHZ, respectively. -- astro-ph.EP

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

Dynamical Stability and Habitability in the HD 20794 System

by Keith CowingMay 28, 2026May 28, 2026

The Keplerian orbit of a terrestrial planet can be a significant driver in the evolution of surface conditions, as well as influencing the overall dynamics of the system.

These panels represent the Lomb-Scargle power for different activity cycle power frequencies found in the dataset of Alpha Centauri A and B. The highest power for a period > 5 years is marked by the blue dashed line which amounts to 22.2 years for Alpha Centauri A and 8.2 years for Alpha Centauri B. Bottom: These panels represent the sinusoidal fit to the MgII index data for Alpha Centauri A and B. The solar MgII index is overlaid in the figure for reference. The solar MgII index is obtained from the LISIRD website (Leise et al. 2019). -- astro-ph.SR

Alpha Centauri, Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Space Weather & Heliophysics, Status Report, Stellar Cartography

Near UV Stellar Activity and Brightness Fluctuations of the Alpha Centauri AB Star System from Weeks to Decades — Inputs for Reflected Light Spectroscopy with HWO

by Keith CowingMay 27, 2026May 27, 2026

We present the most comprehensive near-ultraviolet (NUV: 2550-3255 Angstrom) activity record to date for the Alpha Centauri AB system, combining archival IUE and HST observations spanning nearly five decades with […]

ShaneAO/ShARCS high-resolution imaging of HIP 18512 (left), ShaneAO/ShARCS imaging of HIP 45839 (center), and Keck/NIRC2 high-contrast imaging of HIP 45839 (right). Each image is oriented such that north is up and and east is to the left. HIP 18512 shows a binary at a separation of 10. ′′9 and a position angle of 12.7 ◦ . The Keck/NIRC2 imaging of HIP 45839 shows a faint source at 5. ′′3 which is not consistent with the observed RV trend and astrometric acceleration. A zoomed-in 0. ′′4 × 0. ′′4 cutout of the source is shown in the inset panel. Images are displayed with an arcsinh stretch to capture a large dynamic range (Lupton et al. 2004). -- astro-ph.EP

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

Gaia Exoplanet Orbits, Demographics, and Evolution Survey (GEODES): Characteristics of Three Long-Period Companions Accelerating their Host Stars

by Keith CowingMay 26, 2026May 26, 2026

The upcoming release of Gaia DR4 will yield thousands of giant planet candidates, eventually enabling studies of giant planet eccentricities, masses, and occurrence rates across a broad range of stellar […]

AI - Data - Apps - Cybernetics, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Brown Dwarfs, Gas Giants, Nomenclature, Systematics, Natural History, Status Report, Stellar Cartography

Spectral Classification Of Brown Dwarfs Using Machine Learning

by Keith CowingMay 26, 2026May 26, 2026

Brown dwarfs are compact objects that do not reach temperatures high enough to produce sustained hydrogen fusion. Consequently, they cool over time, gradually evolving through later spectral types.

A demonstration of the limitations of the PSPT data processing pipeline, which did not process the limb uniformly with the rest of the Solar disc. The solid blue line is the stated extent of the solar disk in the original dataset, and the dashed red line is the extent to which the data has been cleaned. Note between the red and blue lines there exists a slight intensity increase — an example of the difference between the processed and unprocessed data separated by this boundary. -- astro-ph.SR

Astronomy & Telescopes, Imaging & Spectroscopy, Space Weather & Heliophysics, Status Report, Stellar Cartography

Astrometric Exoplanet Detection Survives Solar-like Stellar Contamination

by Keith CowingMay 23, 2026May 23, 2026

Astrometric monitoring of stars provides a promising method for discovery of low-mass planets around nearby Sun-like stars.

HR diagram track of the default case (final mass of 2.2 MJ ; see Table 1), showing its surface temperature (Eqs. 12, 19 or 21, depending on the phase) and total luminosity (Eq. 6). Highlighted key moments show the start point (•), detachment (⋆), the point of maximum luminosity (▼), disk dispersal (■), and the age of Jupiter (+). Table 2 lists the corresponding values for time, mass and radius. In the ascending branch small black triangles (▲) show linearly spaced time indicators every Myr. The black dots (•) represent post-detachment intervals equally spaced in log(time). Grey reference lines show two trends: the predicted slope derived in Sect. A, evaluated with the median late-attached-phase surface density of Σpla = 1.7 g cm−2 (labelled with L ∝ T 8 ), and a constant-radius track for Rp = 1 RJ , which approximates a cooling planet in the evolutionary phase before stellar irradiation becomes relevant (last downturn). -- astro-ph.EP

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

Planetary Formation Tracks On The Hertzsprung-Russell Diagram: Visualising The Processes Of Giant Planet Growth

by Keith CowingMay 21, 2026May 21, 2026

The Hertzsprung-Russell diagram (HRD) is central to stellar astrophysics but has rarely been used to interpret planet formation.

Stellar [α/Fe] versus [Fe/H] for planet-hosting stars analyzed in this work (orange circles). The heat map represents the density of stars from APOGEE DR17 in the [α/M] vs [Fe/H] parameter space for reference. The black line approximately divides the thin and thick disk populations (below and above the line, respectively) as defined by D. H. Weinberg et al. 2019. The red points represent stars from the SPOCS sample from J. M. Brewer et al. (2016). The Sun is over-plotted for reference. -- astro-ph.EP

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

A Uniform Determination Of The Bulk Metallicities And Alpha Enrichments Of Confirmed Exoplanet Systems With TRES

by Keith CowingMay 20, 2026May 20, 2026

We present a uniform spectroscopic characterization of 625 F, G, and K stars hosting 859 confirmed exoplanets using high-resolution archival optical spectra from the Tillinghast Reflector Echelle Spectrograph (TRES).

This view of the whole sky was constructed from 96 TESS sectors. By the end of September 2025, when the last image of this mosaic was captured, TESS had discovered 679 exoplanets (blue dots) and 5,165 candidates (orange dots). The glowing arc running through the center is the plane of the Milky Way. The Large Magellanic Cloud can be seen along the bottom edge just left of center. Black areas within the oval indicate regions TESS has not yet imaged. NASA/MIT/TESS and Veselin Kostov (University of Maryland College Park)

Astronomy & Telescopes, Biosignatures & Paleobiology, Citizen Science / Open Science, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release, Stellar Cartography

TESS Planet Hunter Reveals A Map Of The Dazzling Night Sky

by Keith CowingMay 16, 2026May 16, 2026

NASA’s TESS (Transiting Exoplanet Survey Satellite) has released its most complete view of the starry sky to date, filling in gaps from previous observations.

Kiel diagram of analysed stars. Stars analysed in this work are shown as blue dots, those from M22 as orange stars, and those from T25 as green symbols. The two grids correspond to PARSEC isochrones with ages from 0.1 to 14 Ga, in steps of 0.05 Ga, at solar metallicity (Z = 0.013, in purple) and at super-solar metallicity (Z = 0.06, in pink). The cross in the lower left corner indicates representative 1σ uncertainties for this work ( ∆Teff = 110 K and ∆ log g = 0.04 dex). -- astro-ph.SR

Ariel Mission, Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Missions & Hardware, Status Report, Stellar Cartography

Ariel Stellar Characterisation IV. Fundamental Parameters Of 18 Hot Stars In The Ariel Mission Candidate Sample

by Keith CowingMay 15, 2026May 15, 2026

The characterisation of exoplanetary systems depends on the accurate determination of host star parameters.

Comparison of ages for stars with at least one measurement from both asteroseismology and gyrochronology. For stars with only one measurement from either method, the reported age and statistical uncertainties are shown. Gyrochronology generally agrees with asteroseismology for younger stars, but underestimates stellar ages for stars significantly older than the Sun (∼ 4.6 Gyr). astro-ph.SR

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

The HAges Catalog: Stellar Ages For High Priority HWO Target Stars

by Keith CowingMay 15, 2026May 15, 2026

Precise stellar ages (uncertainties ≲1 Gyr, or ∼20% at solar age) are required to discern evolutionary trends in atmospheric biosignatures of terrestrial habitable zone exoplanets surveyed by the Habitable Worlds […]

Stellar Cartography

Dynamical Stability and Habitability in the HD 20794 System

Near UV Stellar Activity and Brightness Fluctuations of the Alpha Centauri AB Star System from Weeks to Decades — Inputs for Reflected Light Spectroscopy with HWO

Gaia Exoplanet Orbits, Demographics, and Evolution Survey (GEODES): Characteristics of Three Long-Period Companions Accelerating their Host Stars

Spectral Classification Of Brown Dwarfs Using Machine Learning

Astrometric Exoplanet Detection Survives Solar-like Stellar Contamination

Planetary Formation Tracks On The Hertzsprung-Russell Diagram: Visualising The Processes Of Giant Planet Growth

A Uniform Determination Of The Bulk Metallicities And Alpha Enrichments Of Confirmed Exoplanet Systems With TRES

TESS Planet Hunter Reveals A Map Of The Dazzling Night Sky

Ariel Stellar Characterisation IV. Fundamental Parameters Of 18 Hot Stars In The Ariel Mission Candidate Sample

The HAges Catalog: Stellar Ages For High Priority HWO Target Stars

NASA Is Forfeiting Its Global Astrobiology Leadership

Curiosity Rover Catches A Stunning Martian Dawn

NASA Spaceline Current Awareness List #1,219 2 October 2026 (Space Life Science Research Results)

Possible News From The Committee on Astrobiology and Planetary Sciences Meeting

Tricorder Tech: An Electrical Technique For Identifying Signs Of Life In Space