Solar and Stellar Astrophysics
White dwarfs, brown dwarfs, cataclysmic variables. Star formation and protostellar systems, stellar astrobiology, binary and multiple systems of stars, stellar evolution and structure, coronas. Central stars of planetary nebulae. Helioseismology, solar neutrinos, production and detection of gravitational radiation from stellar systems
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PSP catalog shows rising occurrence and size, falling Alfvénicity, and 1.5× perpendicular anisotropy
· “Radial Evolution of Near-Sun Magnetic Switchbacks Alfvenicity, Occurrence Rate, and Size”
New seasons of SPIRou data pin the dipole at 0.83 kG and rule out close-in giants
· “Unstable magnetospheric accretion on the T Tauri star TW Hya”
The drop in fast speed near the null amplifies nonlinear deformation, so the wave breaks at a distance away.
Bright structures gain up to 40% intensity and dark areas lose up to 85%, raising contrast and accuracy.
· “A Point-Spread Function for the Extreme Ultraviolet High-Resolution Imager on board Solar Orbiter”
Candidate DESI-HVS1 shows hypervelocity stars include ancient metal-poor members flung 13 million years ago
· “An Old, Low-mass, Metal-poor Hypervelocity Star Candidate Consistent with a Galactic Center Origin”
The shortfall, not measurement error, produces negative residual activity indices in solar-like stars.
· “Revisiting Ca II Activity Indices in FGK Stars: Systematic Biases in Infrared Triplet Measurements”
The vanished pre-explosion object and its 12-16 million year environment favor a low-mass helium star in a binary over a massive single star
New X-ray-to-radio spectra of 12 nearby stars show most would starkly irradiate any Earth-like planet compared to our Sun.
· “Panchromatic Spectra of Nearby Low-mass and Sun-like Stars with Directly Imageable Habitable Zones”
Deep H-alpha imaging finds two concentric nebulous structures around U Geminorum that may be the predicted shells of a recent nova, but…
· “Two Predicted, Concentric Nova Shells Surround the Prototype Dwarf Nova U Geminorum”
M-band CO lines put the star's carbon at 12C/13C ≈ 154, the baseline for its seven planets.
· “The Isotopic and Elemental Abundances of Planet-Host Star TRAPPIST-1”
JWST spectra of two benchmark L dwarfs tie cloud species to host-star composition; one object defies equilibrium.
An empirical line in temperature–gravity space organizes hot Jupiters and brown dwarfs alike.
· “JWST color sequence of transiting exoplanets and directly imaged substellar objects”
A review shows how algorithms winnow rare compact stars from billions of survey sources.
A hot 'sandbar' and a cooler 'shoreline' flank an airless valley of stripped worlds.
· “An Evolving Cosmic Shoreline and Sandbar Bounding the Rocky Airless Valley”
Most disk-hosting intermediate-mass stars remain undiscovered; surviving heavy disks peak where giant planets form.
· “An analysis of the Herbig star population and their protoplanetary disks within 1 kpc”
19 epochs of millimetre imaging trace compact, hot surface features that may drive episodic mass loss.
· “Periodic activity on the (sub)mm surface of the AGB star Mira A”
Inefficient mass transfer and quick spin-down make sub-millisecond pulsars intrinsically rare, not impossible.
Polarized SiO masers trace a loop to eight stellar radii, challenging the dust-driven wind picture for evolved stars.
· “A giant magnetic eruption from the asymptotic giant branch star Mira A”
An active-learning loop labels just 1% of ASAS-SN light curves in 3 hours for $40, surfacing 18 new anomalies.
The fast inspiral erases the milli-Hz signal and leaves a deci-Hz fingerprint for next-generation detectors.
· “Signatures of Compact Object Mergers Inside Stars in AGN Disks”
Hot flares thicken ozone around K stars but crash it to 50% around M stars, reshaping biosignature searches.
Ten outflow-hosting protoclusters show clustering rising with centimetre luminosity per clump mass, tying star birth to cluster assembly.
Daily emergence data for 2010-2019 show holes favor the less active hemisphere and vanish near sunspot maximum.
· “Solar-Cycle Variation of Newly Emerging Coronal Holes during Solar Cycle 24”
Deep eclipses reveal an opaque accretion disc around the white dwarf; two mass solutions agree within 2 sigma.
· “BLG723.31.34651 as an eclipsing Roche lobe-filling sdOB+WD binary”
New multi-spacecraft observations tie the C8.5 flare's jets, electron beams, and particle injections to one null-point process.
· “Breakout/Interchange Reconnection as a driver of Jets, Fast CME, and Solar Energetic Particles”
Multi-band light curves of 26 T Tauri stars return R_T values that match interferometry.
If right, PDS 70 is the youngest exocomet host known and a delivery route for the water JWST sees at 0.05 au.
· “Potential sublimating exocomets around the young star PDS 70”
New abundances for 83 elements point to missing microphysics, not wrong composition, behind the Solar Modelling Problem.
The window is so tight that the 1.174-solar-mass companion of PSR J0453+1559 needs an extreme, unlikely mass loss.
· “Neutron star masses from electron-capture supernovae under equation-of-state uncertainties”
Opposite-phase eclipse timing wobbles show each pair circles a shared center of mass.
· “Six new doubly eclipsing quadruples in a 2+2 architecture”
A Local Neural Operator recovers velocity, magnetic field, current, density and pressure at 30 solar radii.
· “Neural Operator based Multi-Field Reconstruction of Inner Solar Boundary State”
Dust-poor primordial disks around 2 solar-mass stars can match the CO, weak atomic carbon, and absent HCO+ seen in gas-rich debris disks…
· “Thermochemical constraints on a primordial-origin of gas-rich debris disks”
A 12-event STEREO/SECCHI test finds local low-coronal modulation at 80-130 minutes and strongest ensemble organization in upper COR1, but…
Energy released during inspiral could strip 1.5-3.1% of such stars, enough to explain apparently single sdB stars.
· “On the formation of subdwarf B stars via engulfment of substellar companions”
The X-ray flare released 10^36 erg while TESS caught a short optical flare atop an accretion burst.
· “A superflare of BP Tau simultaneously caught by EP X-ray and TESS optical observations”
Neutrons are neutral, yet their magnetic moments can produce plasma-like electromagnetic modes with infinite branches.
· “Plasmon-polaritons in a rarefied nonrelativistic neutron gas”
A self-supervised model places one slow-wind population in the coronal-hole-boundary window, supporting dual-origin slow wind.
· “Discovering Dual-Origin Slow Wind from Solar Orbiter with Self-Supervised Contrastive Learning”
Shocks a dozen parsecs out accelerate electrons to petaelectronvolt energies and carve the radio bow-tie.
Outflow detections push the onset of high-mass star formation earlier than the 70 micron dark phase.
· “MIAO-ALMA: Shocks and Protostellar Outflows in 70 μm-dark clumps with L/M < 1 L_(odot)/M_(odot)”
If the 1949 and 2015 dimmings repeat in 2080, this star is a record-breaking eclipsing binary.
· “WISE J005128.08+645651.7: An enigmatic R Coronae Borealis star”
A 10.2-day detached pair at inclination 82 degrees with mass ratio 0.46; radii and masses await a radial-velocity orbit.
· “CPD-82 291: Multi-sector TESS Photometry and SED Analysis of an Active Eclipsing Binary”
Population-synthesis codes disagree on nearly every merging black hole binary, even for identical starting stars.
The finite-window logarithm of the one-cycle Koopman operator stays bounded at zero detuning and recovers the Kerr jump: Ξ=3.52 vs 3.54
· “Resonance crossings as entire functions of the Koopman operator”
Analogues of Rossby waves driven by magnetic forcing, they may cycle on timescales from months to decades.
Just 0.36% of African-affiliated astronomy papers appear in Africa-based journals; the rest are validated elsewhere.
· “From Timbuktu to SKA: Who owns the Astronomy knowledge Africa produces?”
At moderate extinction, starlight knocks methanol off grain mantles before UV in the gas can destroy it.
· “Gas-phase and Surface Chemistry in the Massive Star-Forming Region RCW\,120”
Simulated events reach a weak second r-process peak near mass number 130, but not a strong third.
· “Nucleosynthesis in the Accretion-induced Collapse of magnetised, Rotating White Dwarfs”
Earth-like planets around most red dwarfs end with near-zero atmosphere protection once tidal spin-down stalls their dynamos.
· “The impact of tidal locking on Earth-like planetary dynamos”
A four-hour H-alpha blue-wing catalog finds small eruptions are far more common than expected and may seed solar-wind switchbacks.
POT3D scales across multi-GPU nodes using only standard 'do concurrent' loops and unified memory.
A 33-solar-mass luminous blue variable is the first known supernova impostor in a high-mass X-ray binary.
· “AT 2016blu: Accretion-Powered Outbursts in a Luminous Blue Variable and Compact Object Binary”
Outer TRAPPIST-1 planets may show less star-spot contamination, improving JWST atmosphere searches.
A 56-clump survey finds infall, shocks, and masers coexisting with cold deuterated gas, implying early feedback.
· “ALOHA IRDCs Molecular Line Follow-up: I. Gas properties and kinematics”
Attention-based model reads 60 minutes of GOES soft X-rays to forecast the peak of C, M, and X flares.
Multi-height inversions and 3-D magnetic field reconstructions tie 300 K heating to a twisted magnetic core.
A silent pulsar's three glitches span 1000x in size; the largest shows a 1.9% superfluid recovery.
· “Discovery of Three Glitches in the previously quiet pulsar PSR J1637-4642”
Ideal and non-ideal MHD yield similar protostellar disks; only the surrounding gas envelope shrinks.
111 are new, and most white-dwarf-locus variability may come from rotating single stars.
· “A Systematic Gaia--ZTF Search for Short-Period Blue Compact-Binary Candidates”
Over a cycle, the shear peak shifts ~0.3 Mm and strengthens, linking subsurface flows to magnetism.
· “Correlations with Magnetic Activity in the Solar Near-Surface Shear Layer. II. Radial Shear”
Ring-diagram data trace the torsional oscillation to 1 Mm and find hemispheric lag asymmetries.
· “Correlations with Magnetic Activity in the Solar Near-Surface Shear Layer. I. Rotation”
A Monte Carlo model now converts STIX count rates into true solar flare X-ray spectra.
· “Responses of the X-ray spectrometer/imager STIX onboard Solar Orbiter”
Trained on one TESS sector, it also screens OGLE, KMTNet, and MOA light curves and estimates event durations.
A cheap stellar-mode model predicts less distortion and later mass return for close black-hole encounters.
Systematic visibility modeling shows substructures emerge late and disk size grows steeply with stellar mass.
Back-evolved debris rings match protoplanetary ring widths, linking the two disk stages without invoking planets.
Band-split ratios and 3-D imaging tie each observed lane to a distinct, differently compressed segment of the CME shock front.
· “Multi-lane type II radio bursts: Insights into shock propagation in the corona”
Fragmentation peaks where optical depth nears unity, giving metal-poor discs a faster route to wide-orbit worlds.
· “A metallicity sweet spot for disc fragmentation and planet formation”
Plotting John Ellard Gore's 1905 luminosity and spectral-class numbers shows the pattern Russell drew three years later.
· “Could John Ellard Gore have pre-empted the Hertzsprung-Russell diagram?”
Exchange and response terms split cleanly, showing that thermodynamic driving alone does not set mode stability.
· “A generalized quadratic balance relation for nonradial nonadiabatic pulsations”
New quadratic calibrations cover 8,400-14,700 K; no model-atmosphere fitting required.
· “An Empirical Effective-Temperature Calibrations for Galactic B/A Supergiants”
The 3,153-candidate catalog within 150 pc also flags 51 disk-bearing stars worth checking for planets.
· “Investigating the properties of nearby young moving groups using GaiaDR3”
Simulated shock chemistry ties fullerene-like PAH defects to 5.2 and 15–18 µm emission in NGC 7023 and MRK 1066.
· “Beyond Idealized PAHs: Infrared Signatures of Carbon-Chain Defects from Shock Synthesis”
Star-derived chemistry points to a bridgmanite-poor, post-perovskite-rich lower mantle at shallower depths.
Using KIC 8410637 and KIC 9970396 as anchors matches dynamical masses without correction factors.
In near-self-gravitating AGN disks, an envelope that outgrows its star collapses into a supermassive star.
The 24-year damage record refuses to follow sunspots or CMEs, so spacecraft lifetimes are hard to predict.
Broad helium and wind lines match starbursts with very massive stars, so quasar counts during reionization need revising.
Its limiting precision is the best reported for any stellar polarimeter on the same figure of merit.
The split appears at entropy 1.75 and may flag supernova explosions of blue supergiants.
Archival UV spectra place HR Del and V842 Cen at 10^-7 solar masses/yr, with lower-rate novae needing a 12,000 K outer disk.
