Open research questions in Stellar, planetary, and galactic studies

What the literature leaves open

• • Accounting for cooler gas at larger disk radii: Previously, YSOpy did not account for flux from gas at temperatures below 1400 K because we cannot use atmospheric models below 1400 K.

  A Parameterized YSO Accretion Disk Model with Increasing Accretion Rate: Predicted Outburst Lightcurves · 2026

• Further observations with the MWA and MeerKAT telescopes, - Analysis of the full SMART survey data, - Investigation of the potential formation channels for this system

  Discovery of a 24 ms Pulsar in a Very Long Orbit with the Murchison Widefield Array · 2026 · DOI

• The paper identifies a gap in the discovery of millisecond pulsars with very long orbits. It highlights the need for further observations to constrain the orbital and spin parameters of PSR J0125−5854.

  Discovery of a 24 ms Pulsar in a Very Long Orbit with the Murchison Widefield Array · 2026 · DOI

• the TMAP models are limited to a specific range of stellar types or parameters, - the use of model atmospheres can be computationally expensive, - the implementation of the Montréal/Tremblay models is based on a specific grid of model spectra

  Physics of Eclipsing Binaries. VI. Hot, Compact Stars · 2026 · DOI

• further development of model atmospheres for a wider range of stellar types, - investigation of the impact of using different model atmospheres on the derived stellar parameters, - exploration of the use of PHOEBE for modeling light curves of compact binaries

  Physics of Eclipsing Binaries. VI. Hot, Compact Stars · 2026 · DOI

• further study of the role of the secondary star in wide binary systems, - investigation of the effects of binary star evolution on exoplanet formation and evolution, - analysis of the properties of exoplanets in different types of binary star systems

  Dynamical Formation of Long-period Exoplanet Systems in Evolving Binary Stars · 2026 · DOI

• The dynamical formation of long-period giant exoplanets has not been well constrained. Few exoplanets are currently known to possess long-period and moderate eccentricities.

  Dynamical Formation of Long-period Exoplanet Systems in Evolving Binary Stars · 2026 · DOI

• unable to obtain high angular resolution imaging for two of the targets, - limited by the faintness of the target and increasing scatter, - reliance on initial estimates from Gaia DR3 XP spectra for TOI-3278

  The TASSIE Program. II: Three Close-In Companions Orbiting Sun-Like Stars · 2026 · DOI

• further study of the migration pathways and radius inflation of hot giant planets, - investigation of the properties of the unconfirmed candidate TOI-3272.01, - continued follow-up of TESS candidates to confirm and characterize exoplanets

  The TASSIE Program. II: Three Close-In Companions Orbiting Sun-Like Stars · 2026 · DOI

• The study only considers simulated data. The analysis is limited to a specific set of biosignatures (H 2 O, O 2 , CO 2 , O 3 ). The study does not account for all possible sources of noise and instrumental systematics.

  On the Impact of Correlated Noise and Spectral Resolution on the Retrieval Analysis of the Habitable World Observatory · 2026 · DOI

• Investigating the impact of correlated noise on retrieval accuracy for other biosignatures. Developing strategies to mitigate the effects of correlated noise on retrieval accuracy. Exploring the potential of joint analyses with other space missions.

  On the Impact of Correlated Noise and Spectral Resolution on the Retrieval Analysis of the Habitable World Observatory · 2026 · DOI

• The information content of a single transit is limited, constraining the Fourier transform of the attenuation map only along at most two radial slices. Realistic effects, such as stellar-limb curvature, can modify the Radon-transform limit. The inverse problem of inferring the planetary attenuation map from transit observations is ill-posed.

  A Radon Transform Perspective on Exoplanet Transits · 2026 · DOI

• Examining how realistic effects modify the Radon-transform limit. Investigating the consequences of relaxing the assumption that the planetary emission map and transmittance map are effectively static. Developing methods to account for stellar-limb curvature and other complexities in transit observations.

  A Radon Transform Perspective on Exoplanet Transits · 2026 · DOI

• Degeneracies present for hydrocarbon features in the wavelength region around 3 μ m, - Limited by the data reduction and retrieval choices, - The study only considers a single planet, HATS-6 b

  GEMS JWST: Hold on to Your HATS(-6 b), a Subsolar-metallicity Giant Planet with Water, Methane, and Ammonia in its Atmosphere · 2026 · DOI

• Further observations and follow-up of HATS-6 b to investigate the excess feature around 3 μ m, - Additional studies to determine the cause of the lower retrieved T eq, - Investigation of other GEMS planets to compare their properties

  GEMS JWST: Hold on to Your HATS(-6 b), a Subsolar-metallicity Giant Planet with Water, Methane, and Ammonia in its Atmosphere · 2026 · DOI

• The analysis is limited by the poor constraints on ϵ ( cos ω , sin ω ) with only the single eclipse measurement available, - The earlier analysis was over-weighting of the eclipse timing, - The presence of a second planet might have long ago been ejected or might still be present

  Eclipse Timing of the Eccentric Planet HD 80606 b with JWST: Constraints on a Second Planet and Other Dynamical Effects · 2026 · DOI

• Further analysis of the eclipse timing and radial velocity data to investigate the presence of a second planet, - Investigation of the internal properties of the planet if orbital effects can be attributed to the effects of tidal dissipation, - Continued monitoring of HD 80606 b's orbit to detect any changes due to General Relativity or tidal torques

  Eclipse Timing of the Eccentric Planet HD 80606 b with JWST: Constraints on a Second Planet and Other Dynamical Effects · 2026 · DOI

• The sparse temporal sampling of Gaia does not allow for detailed tracking of the temporal evolution of a flare event. Distinguishing genuine flare events from instrumental or calibration artefacts. Estimating the flare energy due to the limited integration time of a single G-band transit.

  Gaia method paper: An algorithm to detect flare events in Gaia time series · 2026 · DOI

• future Gaia flare catalogues, - high-cadence missions such as Kepler and TESS for complementary views of stellar flaring activity

  Gaia method paper: An algorithm to detect flare events in Gaia time series · 2026 · DOI

• Investigating the sensitivity of CS2 chemistry to elemental enrichment - Assessing the impact of enhanced UV irradiation on CS2 production - Exploring the dependence of CS2 formation on T eq in a wider range of gas giant exoplanets

  Photochemical Production of CS 2 in Temperate-to-warm Gas Giant Exoplanet Atmospheres · 2026 · DOI

• the detailed chemical pathways responsible for the formation of CS2 remain poorly understood - there is a lack of understanding of how CS2 production depends on Teq - the current observations of CS2 in gas giant exoplanets lack a unified framework for interpretation

  Photochemical Production of CS 2 in Temperate-to-warm Gas Giant Exoplanet Atmospheres · 2026 · DOI

• Further study of the formation of AF Lep b, - Investigation of the C/O ratios of other planets and their host stars, - Analysis of the abundances of other elements in the planets and their host stars

  A High-resolution Spectroscopic Survey of Directly Imaged Companion Hosts. III. Characterization of the Cold Imaged Planet Hosts AF Lep A and ϵ Indi A · 2026 · DOI

• The paper identifies a gap in the understanding of the formation of imaged planets and the role of core accretion and gravitational instability. It highlights the need for determining the atmospheric parameters and elemental abundances of the host stars to interpret the abundances in the atmospheres of directly imaged planets.

  A High-resolution Spectroscopic Survey of Directly Imaged Companion Hosts. III. Characterization of the Cold Imaged Planet Hosts AF Lep A and ϵ Indi A · 2026 · DOI

• (2025), the magnetospheric accretion model may not be applicable to the burst of Gaia21bja.

  Gaia21bja: pre-main sequence star with quasi-periodic bursts · 2026

• The Spectroscopic PAtch Model for Massive Stars (SPAMMS) accounts for these effects, but its applicability has been limited by the spectral types covered by its model atmosphere grids.

  SPAMMS: 3D spectroscopic modelling of stellar surfaces. II. Implementation of Kurucz and TLUSTY model atmospheres · 2026

Most-cited papers in Stellar, planetary, and galactic studies

• Kepler Planet-Detection Mission: Introduction and First Results · Science · 2010 · 3,579 citations
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope · Astronomy and Astrophysics · 2022 · 685 citations
• Modules for Experiments in Stellar Astrophysics (MESA): Time-dependent Convection, Energy Conservation, Automatic Differentiation, and Infrastructure · The Astrophysical Journal Supplement Series · 2023 · 607 citations
• Early Release Science of the exoplanet WASP-39b with JWST NIRSpec G395H · Nature · 2023 · 274 citations
• A time-resolved picture of our Milky Way’s early formation history · Nature · 2022 · 234 citations
• Observational constraints on the origin of the elements · Astronomy and Astrophysics · 2022 · 222 citations
• Updated Gaia -2MASS 3D maps of Galactic interstellar dust · Astronomy and Astrophysics · 2022 · 196 citations
• Early Release Science of the exoplanet WASP-39b with JWST NIRCam · Nature · 2023 · 194 citations
• High Tide or Riptide on the Cosmic Shoreline? A Water-rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ 486b from JWST Observations · The Astrophysical Journal Letters · 2023 · 185 citations
• The JWST Early-release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 μm Spectrum of the Planetary-mass Companion VHS 1256–1257 b · The Astrophysical Journal Letters · 2023 · 173 citations

Most recent work

• Supermassive Stars Match the Spectral Signatures of JWST’s Little Red Dots · The Astrophysical Journal · 2026
• A free-floating-planet microlensing event caused by a Saturn-mass object · Science · 2026
• Enrichment by the first stars in a relic dwarf galaxy · Nature Astronomy · 2026
• Precise Radial Velocities · Annual Review of Astronomy and Astrophysics · 2026
• The LBT Y p Project. I. An Improved Determination of the Primordial Helium Abundance—Project Description, Sample Selection, Observations, and Methodology · The Astrophysical Journal · 2026
• White Dwarfs with Infrared Excess from LAMOST Data Release 11 · The Astrophysical Journal · 2026
• Cloudy mornings and clear evenings on a gas giant exoplanet · Science · 2026
• Limits on forming coreless terrestrial worlds in the TRAPPIST-1 system · Monthly Notices of the Royal Astronomical Society · 2026
• The Distribution of Blue Straggler Stars in the Color–Magnitude Diagrams of Old Open Clusters* · The Astronomical Journal · 2026
• Using Lithium and Beryllium to Study the Structure and Evolution of Rotating Stars: The Spite Plateau of Halo Stars · The Astrophysical Journal · 2026

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