太阳与恒星天体物理

Active M dwarfs exhibit frequent and energetic flares that provide a unique laboratory for studying chromospheric heating processes under extreme magnetic activity. To probe the flare process of M-dwarfs, we present a high-resolution…

Radio waves propagating through an inhomogeneous, turbulent medium such as the solar corona and solar wind become distorted, causing the initially plane wavefronts becomes corrugated and acquire an RMS phase deviation across the wavefront.…

We present a semi-empirical reconstruction of the pulsation behavior of the classical Cepheid delta Cephei using observed Johnson-V photometry, HARPS-N radial velocities, and published SPIPS pulsation-model curves. A cleaned AAVSO Johnson-V…

We present an empirical Fourier reconstruction of the observed Johnson-V light curve of the prototype Classical Cepheid Delta Cephei. The goal is not to infer a full physical stellar model but to establish a reproducible…

Globular clusters do not undergo conventional chemical evolution driven by supernova enrichment. Instead, they exhibit unique abundance patterns of the light elements, which cannot be fully explained by any of the proposed enrichment…

Energy conversion by reconnection-powered nanoflare heating is one of the leading explanations for the heating of the solar chromosphere and corona. The aim of this paper is to shed light on this mechanism by exploring the magnetic Reynolds…

SN 2021yfj is a recently discovered interacting supernova that exhibits narrow emission lines of Si, S, and Ar, indicating the presence of circumstellar material (CSM) enriched with these elements surrounding the progenitor prior to the…

Long-period transients (LPTs) are radio sources that exhibit polarized periodic radio bursts on time-scales of minutes to hours. At least some LPTs are associated with white dwarfs (WDs) in close binary systems. However, the evolutionary…

The presence of coherent oscillatory signatures in Parker Solar Probe SWEAP datasets, identified through a series of spectral analyses, is addressed, and their possible connection to oscillatory phenomena in HMI/SDO datasets of active…

Accurate modeling of stellar active regions (ARs) remains a major bottleneck for radial-velocity and transmission-spectroscopy studies aimed at finding Earth-like planets. While much effort has been devoted to AR modeling, their…

Particle acceleration is a fundamental astrophysical process occurring across diverse systems and scales, producing electromagnetic emission across all wavelengths. Radio bursts from astrophysical systems like active galaxy jets, solar…

We present a new spectroscopic view of the brown dwarf population in the young star-forming region IC 1396 and investigate the impact of environment on low-mass star formation. We use deep optical photometry from Subaru-HSC to identify the…

We report the first detection of the `convective-transition gap' (also known as `M-dwarf gap') in the globular cluster 47 Tuc (NGC 104) thanks to Euclid data. This feature, linked to a change in the physical properties of late-type dwarfs,…

We present a projection method for controlling numerical \(\nabla\cdot\B\) errors in smoothed particle magnetohydrodynamics (SPMHD). The method corrects the magnetic field after an MHD update by solving an elliptic projection problem…

While massive stars are frequently found in triple architectures, the lack of observed parameter distributions has long remained a bottleneck for statistical models of their evolution. We compile the first representative set of physical and…

This study explores multiple aspects of W Ursae Majoris (W UMa) contact binary systems with low mass ratios, providing empirical insights into their definition, structure, rotational stability, and parameter relationships. We first examined…

Stellar radio emission is highly variable with stellar flares lasting from milliseconds to hours. For some stars, their flares or bursts can repeat once every couple of hours, while other stars may flare only once in hundreds of hours of…

Flare ribbons form as a result of energy deposition associated with particles accelerated in low layers of the solar atmosphere. The fine-scale structures of flare ribbons, also called ribbon kernels, offer a potentially powerful diagnostic…

Context: Westerlund 1 (Wd1), the most massive young star cluster in the Milky Way, is an excellent laboratory for studying star formation and early stellar evolution in a starburst-like environment. However, high extinction restricts…

For sixty years, stellar evolutionary models have predicted that intermediate-mass stars slightly contract on the terminal-age main-sequence (TAMS) as they exhaust hydrogen in their convective cores, producing the main-sequence (MS) hook on…