New papers on Stars & the Sun
97 new papers on stars & the sun in the last 7 days, within Space & cosmos. These are the 50 Pipette rates most worth reading, with the main result in the authors' own words.
The best of the week
JWST Observations of the Metal-poor T Dwarf WISEA J155349.96+693355.2: The First Brown Dwarf Associated with the Gaia-Enceladus Milky Way Substructure
The UVW kinematics of WISEA J155349.96+693355.2, its bulk metallicity, and its modest alpha enrichment ([/Fe] = +0.15 dex) are all equivalent to stars identified in the Gaia-Enceladus Milky Way substructure, making it the first brown dwarf with kinematic and chemical evidence of association.
PreprintClaims a big stepDKIST unveils MHD-predicted sub-50 km photospheric vortices
These results demonstrate the unique capability of DKIST to resolve the population of photospheric convective vortices predicted by state-of-the-art magnetoconvection simulations, opening a new observational window into small-scale solar convective dynamics.
PreprintClaims a big stepFirst Observation of a Polar Coronal Hole-like Fast Solar Wind Stream in the Sub-Alfv\'enic Solar Corona: an Analysis of Turbulence Properties
At heliocentric distances of approximately 10 solar radii, with speed mostly above 400 km/s, this interval is a first example of "polar coronal hole-like (PCH-l) fast" solar wind observed in the sub-Alfv\'enic solar corona.
PreprintClaims a big stepMetal-poor Brown Dwarf Kinematics from JWST NIRSpec Spectroscopy
Our study systematically demonstrates that JWST G395H spectroscopy can provide robust RVs in addition to detailed chemical abundances, necessary for Galactic archaeology studies.
PreprintClaims a big stepCoronal Green-Line Emission During a Solar Prominence Eruption: Spectroscopic Evidence of Its Correspondence with the EUV Late Phase
To our knowledge, this study provides the first space-based spectroscopic evidence linking coronal green-line emission with the ELP and its origin during a solar flare.
PreprintClaims a big step3D Radiation Hydrodynamics of Blue Supergiant Envelopes
We present the first 3D radiation hydrodynamical simulation of the outer envelope of a blue supergiant.
PreprintClaims a big stepHigh-Resolution Modelling of Coronae and Winds in Solar-type Stars with Varying Rotation Rates II. Stellar Winds
Building on the successful reproduction of X-ray coronae in our Paper~I, we obtain the first self-consistent activity--wind relation in a unified modelling framework: the mass-loss rate scales with the surface X-ray flux following a power law with an index of .
PreprintGas phase Elemental abundances in Molecular cloudS (GEMS) XII. First look into the para-to-ortho ratio of c-C3D2 towards prestellar cores
We present new detections of ortho and para transitions of c-C3D2 toward three Taurus molecular cloud sources from the GEMS Large program, and revisit four literature cores to investigate the para-to-ortho ratio of c-C3D2 for the first time.
PreprintClaims a big stepPROSWIN: Probabilistic Solar Wind Speed Forecasting Using Deep Distributional Regression From Solar Images
We present PROSWIN, a probabilistic machine learning model that forecasts the hourly solar wind speed (SWS) at Earth with a four-day lead time.
PreprintReal-world useDistinct Population of Wolf-Rayet Stars in the Low-Metallicity Galaxy NGC 6822. Quantitative analysis of optical and UV spectra of the complete sample
We report a discovery of a low luminosity stripped qWR star in NGC 6822, and conclude that the WR star population in NGC 6822 and the SMC are distinct despite similar metallicities of their host galaxies.
PreprintEvidence for the emergence of stellar magnetic fields during rapid mass transfer
The system provides a rare opportunity to observe the immediate aftermath of mass transfer in a massive binary and offers compelling new evidence linking binary interaction to the emergence of strong stellar magnetism.
PreprintBold claims, read criticallyFirst X-ray detection of symbiotic nova CN Cha with eROSITA/SRG
We report on the first X-ray detection of the symbiotic star CN Cha with eROSITA (extended Roentgen Survey with an Imaging Telescope Array) onboard Spektrum-Roentgen Gamma (Spektr-RG). Methods.
PreprintQuantum Phase Transitions in Nuclei and the Origin of Rhodium
Here we show that the enhancement found in the solar system of rhodium and ruthenium isotopes compared to neighboring isotopes can serve as such a feature.
PreprintCRIMSONS: An Online Tool for Modeling Chemical Enrichment with Stochastic IMF Sampling
Here, we present CRIMSONS, the first online tool designed to model chemical enrichment while self-consistently incorporating these three ingredients.
PreprintCHASE Spectral Survey I: Measuring Contamination in the Color-selected J-region Asymptotic Giant Branch Distance Indicator
We report the observations of 76 stars (54 within the standard JAGB selection box of 1.5 < J - K < 2.0 mag) and find only 13 of 54 stars are carbon-rich, a 766 oxygen-rich contamination under blind photometric selection.
PreprintDisc-mediated angular momentum transport resolves the mass-gain problem in rotating binaries
We introduce a disc-mediated angular momentum transport prescription for mass-transfer onto stellar companions.
PreprintThe Last Gasps of a Dying Star: ALMA Observations of the Pre-Planetary Nebula IRAS 06530-0213
These data show the presence of an extended circular ring -- first evidence of the last thermal-pulse preceding the post-AGB phase in a carbon star -- and a central bipolar nebula (CBN) and torus.
PreprintSuper-Chandrasekhar white dwarfs by the evolution of magnetized main-sequence stars: New mass-limits from STARS simulation
We further investigate the stability of magnetized WDs, both below and above the Chandrasekhar limit and confirm the possibility of super-Chandrasekhar B-WDs with new mass limits that depend on the magnetic field geometry, mass accretion from a companion and cooling rates.
PreprintThe Treasury of Extremely Metal-Poor O Stars
We show that correlates with host galaxy metallicity across 5-50% and find tentative evidence of a steeper decline in wind strength below 10% .
Preprint with a published versionUsing Machine Learning to Model Stellar Collisions in our Galactic Center
We utilize the newly developed , a machine learning tool developed to predict the outcomes of stellar collisions, to bridge 3D hydrodynamic simulations of stellar collisions with a dynamical model of the Galactic center.
PreprintThe protostar FU Orionis may not be bursting: dramatic accretion suppression in embedded young eccentric binaries
This dramatic suppression and burst near periastron is a physical mechanism for strong variable accretion in embedded young eccentric binaries.
PreprintBold claims, read criticallySequential Star-Formation and the Near-Infrared Stellar Populations within N159
The distribution of stellar and candidate YSO populations across N159 reveal more evolved star-forming populations in the N159E region and newer star formation in the N159W region, supporting the sequential star formation scenario for this region.
PreprintThe physics of deep-interior convective shell boundaries in a massive pre-supernova star: Internal gravity wave mixing at the peak
Our simulations show that the dominant physics at this boundary is mixing due to internal gravity waves.
PreprintBold claims, read criticallyComparing phylogenetic trees of stars with spectral graph distances
In contrast, spectral distances vary smoothly with perturbation amplitude and provide a label-invariant method for comparing trees built from disjoint sets of stars.
PreprintHydrogen Line Emission in Accreting Low-Mass Objects I: Spectral Analysis of Shock-Origin Narrow Component
We find that shock emission dominates the hydrogen-line emission at object masses or free-fall velocities , but becomes minor at .
PreprintNew Optical and Mid-Infrared RR Lyrae Period-Luminosity-Metallicity Relations for Precision Distances and Metallicity Distributions in the Magellanic Clouds
We present in this work the latest empirical RRL period-luminosity-metallicity (PLZ) and period-Wesenheit-metallicity (PWZ) relations combining optical () and mid-infrared data () using OGLE and WISE photometry, anchored to Gaia DR3 parallaxes.
PreprintPredicting low-latitude ionospheric Total Electron Content (TEC) over the Indian sector under variable space weather conditions using solar wind parameters
The results indicate that solar wind parameters, combined with the F10.7 solar flux and cyclical temporal encoding, contain sufficient information to reproduce geomagnetic storm-time TEC variability.
PreprintReal-world useThe "Other" Centuries-Long Record of Solar Magnetic Activity Cycles: Lessons From the Stars
These records show that solar-like dynamos are a common feature of Sun-like stars, and magnetic grand minimum events akin to the Maunder minimum might be very rare, with only one identified in 3,000 star-years of magnetic activity records.
PreprintInflated Supermassive Stars as Little Red Dots and Progenitors of Supermassive Black Holes
For M= to Msun and metal mass fractions to , we find that the most metal-rich models (Z ~ ) develop highly inflated envelopes and reach Teff ~ 7000 K. We suggest that such enriched SMSs could instead be assembled through runaway stellar collisions in compact star clusters.
PreprintA High Resolution View of Three Massive Young Stellar Objects in the Magellanic Clouds
Using ALMA band 7 long-baseline observations, we present the highest resolution (approximately 0.03", ) view to date of three massive young stellar objects (MYSOs) in the Magellanic Clouds, i.e., Lh03 and Lh09 in the LMC, and S07 in the SMC.
PreprintN/O-enhanced chemical enrichment by massive stars: the interplay of optically-thick winds and rotation
The optically-thick-wind scenario can reproduce the nebular C, N, O, and He abundance patterns of three representative high- galaxies showing direct WR signatures: RXCJ2248-ID, Sunburst Arc, and MARTA 4327, with stellar metallicities and ages similar to those inferred from SED-fitting.
PreprintCode availableStellar flare detection and characterization in ZTF High-cadence light curves
In this paper, we have developed a pipeline to detect and characterize flares in short-duration (approximately 6.2-hour) light curves from the Zwicky Transient Facility (ZTF) Extended Deep-Drilling survey.
PreprintInterstellar extinction of classical Cepheids from neighboring stars I. Methodology and application to 16 Galactic Cepheids
We present an innovative methodology relying on the analysis of neighboring field stars and apply it to a pilot sample of 16 Cepheids.
PreprintGIARPS simultaneous optical and infrared high-spectral-resolution observations of Cepheids I. Limb darkening from cross-correlated radial velocities
This work shows that the differential limb darkening of Cepheids in visible and H bands, and consequently the geometrical part of the projection factor, follows what is expected from stellar atmosphere models.
PreprintStellar ages from [C/N] in giant stars: applicability and limitations
Our results demonstrate that [C/N], combined with metallicity, is an effective empirical tool for deriving stellar ages of giant stars from spectroscopic surveys, particularly for LRGB stars with [Fe/H] > -1, enabling Galactic archaeology studies beyond the reach of current asteroseismic samples.
PreprintThe oldest low- thin disc stars
Using GALAH DR4, we provide evidence that the -poor stars coexist with -rich stars up to 12.5 Gyr.
PreprintTriggering star formation by free-floating planets
A sufficiently massive planet can become an alternative dynamic center for the contracting cloud.
PreprintBold claims, read criticallyStellar flares with Ariel: detection prospects and impacts on exoplanet spectroscopy
These results demonstrate stellar flares represent both a valuable ancillary science case and a potential source of contamination for Ariel observations, highlighting the need for improved flare models and mitigation strategies to maximize the mission's scientific return.
PreprintCME Kinematics with Optical Flow: Multi-Coronagraph Insights into Internal Velocity Dispersion
These findings confirm that CMEs contain complex internal flows and layered substructures within the traditional three-part morphology.
PreprintElemental Abundances of Cool Stars: A Spectroscopic Framework Applied to Five Planet-Host Stars
We apply our framework to SPIRou YJHK spectra of five planet-host stars--GJ 9827, K2-18, TOI-1201, TOI-1685, and Barnard's Star--and derive abundances of C, O, Na, Mg, Al, Si, K, Ca, Ti, Cr, Mn, and Fe for all five stars, plus Sc, V, and Ni for a subset, with typical uncertainties of dex.
PreprintCurrent Sheet Fragmentation in the Course of Repeated Eruptive Magnetic Flux Emergence
These results demonstrate that eruptive flux emergence can self-consistently transform a global reconnecting current sheet into a localized, intermittent, sheet-dominated dissipative network, providing a natural environment for impulsive coronal heating and motivating future particle-acceleration studies.
PreprintCause of chromospheric opposite polarity intrusions discovered in Sunrise III/SCIP data: MURaM-ChE simulations point to twisted flux ropes
The magnetic field configurations associated with the OPI features appear to belong to twisted flux ropes (TFRs) and are visible for most of the time in the presented 21 min time series.
Preprint with a published versionA Quantitative Method to Investigate the Spectral Class Time Evolution of Novae
These results support the interpretation of Fe II, He/N, and hybrid spectra as evolutionary stages rather than distinct nova types and establish as a quantitative tool for tracing nova spectral evolution while reducing biases from incomplete spectroscopic coverage.
PreprintTIC 366240660 - A Dynamically Active Triple With a Very Short Outer Period of 30.5 Days
Results: With an outer orbital period of only 30.5 d, this is the second most compact triple reported in the literature.
PreprintGravity-driven Emergence of Multi-fractal Density Structure in the Orion A Integral Shaped Filament
The ISF therefore does not follow a single local density-scaling exponent but exhibits multi-fractal density scaling.
PreprintStudy of Chromospheric Global-Scale Flows using Local Correlation Tracking Across the past 10 Solar Cycles
These results extend the observational context for solar-cycle-related flows over a century and motivate further refinement through data-driven reconstruction.
PreprintAre there really some eccentric eclipsing binaries having orbital periods below 1 d?
Therefore, we performed a thorough analysis of all these eclipsing binaries (>140), showing that the vast majority of the published systems (> 98%) are in fact circular.
Preprint with a published versionSpectroscopic Study of the Circularly Polarised Radio Source TYC 2834-1385-1: An Active Binary
This represents one of the first spectroscopic confirmations of a chromospherically active binary following its identification in a low-frequency radio survey.
Preprint with a published versionXMST II: The spatial and kinematic structure of Galactic OB associations in Gaia DR3
The main result is that physically different observables can refine an existing spatial hierarchy without redefining its me
Preprint with a published versionA Multiwavelength View of Oph II: Disentangling the Variability of the Multi-Star Component C
Taken as a whole, the multi-epoch and -wavelength data presents a consistent picture of Oph C as a rare trinary system composed of a hot star and two cool stars.
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