太阳与恒星天体物理

Multi-wavelength studies of their circumstellar environments around LBVs are essential to quantify their feedback at Galactic scales. Dominant emission mechanisms at millimetre wavelengths are, however, still poorly understood. Stellar…

Although asteroseismology is regarded as the most powerful tool for probing stellar interiors, seismic modelling remains dependent on global stellar parameters. Stellar clusters offer direct measurements of these parameters by fitting a…

The heating and structure of the solar chromosphere depends on the underlying magnetic field, among other parameters. The lowest magnetic flux of the solar atmosphere is found in the quiet Sun internetwork and is thought to be provided by…

Carbon-rich Wolf-Rayet (WR) stars are significant contributors of carbonaceous dust to the galactic environment, however the mechanisms and conditions for formation and subsequent evolution of dust around these stars remain open questions.…

Shocks in the solar corona can accelerate electrons that in turn generate radio emission known as type II radio bursts. The characteristics and morphology of these radio bursts in the dynamic spectrum reflect the evolution of the shock…

Aims. We present and analyse the detailed physical properties of six binary stellar systems, originally proposed as possible star-black hole binaries on the basis of radial velocities from Gaia's third data release, but soon recognised as…

On the basis of monotonic orbital-period variations, this study aims to identify genuine relationships between binary parameters and the rates of mass transfer (MT), mass loss (ML), and angular momentum loss (AML). Sample binaries with…

Linearly polarized dust emission traces the plane-of-sky magnetic field structure, thus allowing us to investigate the role of magnetic fields in the formation and evolution of cloud cores. In this work, we present observations of dust…

We present the results of an investigation into the possible presence of magnetic activity cycles in stars observed in two observational campaigns by the K2 mission. This study was based on the KEYSTONE asteroseismic sample of solar-like…

We report a point spread function (PSF) and deconvolution procedure to remove stray light from the Helioseismic and Magnetic Imager (HMI) data. Pre-launch calibration observations, post-launch Venus transit and lunar transit data were used…

The B[e] phenomenon discovered nearly 50 years ago features the presence of forbidden emission lines due to extended and dense circumstellar gas and large IR excesses due to the radiation from circumstellar dust in a wide variety of objects…

We perform three-dimensional hydrodynamic simulations of two idealized regimes of stellar convection: a cooling-driven model (Model C) and an entropy-gradient-driven model (Model S). The two regimes exhibit striking contrasts: while Model S…

Rapidly rotating late M dwarfs are observed in two different branches of magnetic activity, although they operate in the same stellar parameter range. Current empirical evidence indicates that M dwarfs with spectral types ranging from M3 /…

We present observations and analyses of five little-studied cataclysmic binary stars in the southern celestial hemisphere. Our new observations are from the South African Astronomical Observatory. The objects and salient results are as…

Research on young stellar populations is essential to understand the properties of embedded clusters and advance theories of their formation. This has driven advancements in methodologies for star detection, leading to the development of…

Small-scale transient jetlet activity and associated upflows from coronal hole plumes are potential sources of the solar wind. To elucidate the magnetic origins and driving mechanisms of such upflows, we perform three-dimensional radiative…

The extended Main Sequence Turn-off (eMSTO) in the open cluster NGC 2355 is investigated using precise astrometry and photometry from Gaia DR3 and spectroscopic data from the Gaia-ESO Survey. We find a clear positive correlation between the…

Massive stars can exhibit giant eruptions with high mass loss shortly before their explosion as a core-collapse Supernova. These multiple giant eruptions (MGEs) may have a commutative effect that brings the star to a different state,…

Type Ia supernovae are thermonuclear explosions of white dwarfs, yet the nature of their progenitor systems remains uncertain. Recent discoveries of hypervelocity stars provide unique constraints, as these stars likely represent the…

I report on the high resolution spectra of the remarkable X9 solar flare of 2024 Oct 03 (SOL2024-10-03T12:08) and evaluate the extent to which nonthermal electron beams that generate dense chromospheric condensations can power very bright…