astro-ph.SR Archives

Example stellar spectra of HAT-P-47 (T; solid line) and its reference star (R; dotted line), observed with LBT/MODS1B (blue), LBT/MODS1R (magenta), LBT/MODS2B (yellow), and GTC/OSIRIS+ (green). The vertical lines with gray-shaded regions indicate the adopted spectroscopic passbands. -- astro-ph.EP

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

Optical Transmission Spectrum Of HAT-P-47b: Evidence For Aerosols And Tentative TiO Absorption

by Keith CowingJune 1, 2026June 1, 2026

Transmission spectroscopy enables the characterization of exoplanet atmospheres by probing absorption features in their terminator regions.

Astronomy & Telescopes, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Habitable Zones, Radiation, Space Weather & Heliophysics, Status Report

Exploring Space Weather From Young Solar-like Stars as Windows to Exoplanetary Habitability

by Keith CowingMay 28, 2026May 28, 2026

Young solar-like stars are efficient generators of magnetic activity, superflares, coronal mass ejections (CMEs), and stellar energetic particles. These phenomena drive the early evolution of stars and shape the habitability […]

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 […]

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.

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 […]

The H2 and [Ne II] emission detected towards DoAr 25 on top of the ALMA 240 GHz continuum emission (shown in the background as a reddish-yellow image). The white central circle shows the inner working angle from JWST. In this case, the disk itself is seen in absorption against line emission from the Ophiuchus PDR for H2 S(1)-S(3) (17.03-9.66 µm). -- astro-ph.SR)

Astrochemistry, Astronomy & Telescopes, Imaging & Spectroscopy, Interstellar, Space Weather & Heliophysics, Status Report

Characterizing The Extended Molecular Hydrogen Winds In Protoplanetary Disks From The JWST Disk Infrared Spectroscopic Chemistry Survey

by Keith CowingMay 12, 2026May 12, 2026

We present a comprehensive analysis of extended H2 emission from 34 protoplanetary disks observed with the JWST Disk Infrared Spectroscopic Chemistry Survey (JDISCS), supplemented by archival data.

Cumulative flare-frequency distribution of TRAPPIST-1.

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Space Weather & Heliophysics, Status Report, TRAPPIST-1

A Single Power Law For The TRAPPIST-1 Flare Distribution Across Four Orders Of Magnitude In Energy

by Keith CowingMay 9, 2026May 9, 2026

TRAPPIST-1 is an ultra-cool dwarf that flares frequently. These flares shape the surrounding planets’ high-energy irradiation environments, with consequences for atmospheric chemistry and escape, and they can contaminate transmission spectroscopy […]

log R′HK(Teff) as a function of age for solar twins and solar analogs. Blue squares represent the six new seismic solar analogs listed in Table 1. Orange, dark-gray, and light-gray circles correspond to stellar samples from the literature, as indicated in the legend. The dashed line shows the empirical relation from Lorenzo-Oliveira et al. (2018). The green shaded region represents the 2σ uncertainty envelope around this relation. The Sun is represented by its red symbol. -- astro-ph.SR

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

Characterizing Six Seismic Solar Analogs Observed By Kepler, K2, And HERMES

by Keith CowingMay 3, 2026May 3, 2026

Solar analogs, stars that closely match the fundamental properties of the Sun, provide key benchmarks for testing stellar structure and evolution across different ages and activity levels.

Starting from the top left corner and moving in a clockwise direction are the companions we detected to 2MASS J01283952-1458042, PM J02024+1034 A, 2MASS J05103956+2946479, 2MASS J07171706-0501031, 2MASS J10430293-0912410, and 2MASS J19445376-2337591. These reconstructed images sometimes contain a third “ghost peak” due to low SNR resulting in a lack of phase information. As noted in Section 3.1, the companions to 2MASS J05103956+2946479 and 2MASS J07171706-0501031 are unbound. -- astro-ph.SR

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

The POKEMON Speckle Survey of Nearby M dwarfs. IV. Distance-Limited Catalog (POKEMON-DLC)

by Keith CowingApril 29, 2026April 29, 2026

The Solar Neighborhood is dominated by stars smaller, colder, and fainter than the Sun: the M dwarfs.

astro-ph.SR

Optical Transmission Spectrum Of HAT-P-47b: Evidence For Aerosols And Tentative TiO Absorption

Exploring Space Weather From Young Solar-like Stars as Windows to Exoplanetary Habitability

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

Spectral Classification Of Brown Dwarfs Using Machine Learning

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

Characterizing The Extended Molecular Hydrogen Winds In Protoplanetary Disks From The JWST Disk Infrared Spectroscopic Chemistry Survey

A Single Power Law For The TRAPPIST-1 Flare Distribution Across Four Orders Of Magnitude In Energy

Characterizing Six Seismic Solar Analogs Observed By Kepler, K2, And HERMES

The POKEMON Speckle Survey of Nearby M dwarfs. IV. Distance-Limited Catalog (POKEMON-DLC)

Offworld Expedition Training: Astronauts Explore An Ancient Earth Volcano

Orbital Bioscience: Organoids Cultured In Microgravity

JWST Detection Of Methane Emission From A Young Brown Dwarf

Revealing The Shiny Nature Of Lava Worlds: Small Planet Phase Curves With TESS

Simulated Effects of Radioactive Elements on Magnetic Evolution and Atmospheric Mass Loss of Earth-like Planets