太阳与恒星天体物理

We report the discovery of SDSS~J022932.28+713002.7, a nascent extremely low-mass (ELM) white dwarf (WD) orbiting a massive ($> 1\,M_\odot$ at 2$\sigma$ confidence) companion with a period of 36 hours. We use a combination of spectroscopy,…

Slow magnetoacoustic waves with a 3 minute period are upward-propagating waves traveling through the density-stratified umbral atmosphere. The decreasing density causes their amplitude to increase, developing into nonlinear waves through…

As the two Voyager spacecraft traveled beyond the heliosphere, they encountered a magnetic field environment that had never been observed before. Studies have attempted to characterize this new regime by examining the magnetic field…

PG 1159 stars are thought to be progenitors of the majority of H-deficient white dwarfs. Their unusual He-, C-, and O-dominated surface composition is typically believed to result from a late thermal pulse experienced by a single…

The mass discrepancy problem, observed in high-mass stars within eclipsing binaries, highlights systematic differences between dynamical and evolutionary mass estimates, challenging the accuracy of stellar evolution models. We aim to…

Magnetic reconnection and Magnetohydrodynamic (MHD) waves may well be both playing a role in coronal heating. In this paper, we simulate reconnection in the corona as a response to the convergence of opposite-polarity magnetic sources at…

We determine magnetic fields from the photosphere to the upper chromosphere combining data from the Hinode satellite and the CLASP2.1 sounding rocket experiment. CLASP2.1 provided polarization profiles of the Mg~{|sc ii} $h$ and $k$ lines,…

Context: In a recent publication, we established a close relationship between light-curve asymmetries in Mira variables and indicators of their dust mass-loss rate. The light-curve asymmetries appear to be related to the stars' third…

We introduce MVPinn, a Physics-Informed Neural Network (PINN) approach tailored for solving the Milne-Eddington (ME) inversion problem, specifically applied to spectropolarimetric observations from the Big Bear Solar Observatory's…

There is a relatively large population of known double white dwarfs (DWDs) that were mostly discovered through spectroscopic observations and by measuring their radial velocity variations. Photometric observations from these systems give us…

We examine recent astronomical data to assess whether the sun and Solar System possess anomalous properties compared to other stars and exoplanetary systems, providing context for astrobiology research. Utilising data primarily from large…

The transient optical source MASTER OT J072007.30+451611.6 has been recently discovered and proposed as a peculiar polar with an unusually high amplitude of the orbital brightness variation in the optical of $\sim$3 mag. To clarify its…

In the late stage of their evolution, low- to intermediate-mass stars pass through the asymptotic giant branch (AGB) phase, characterised by strong mass loss through dust driven winds. High angular resolution observations reveal that these…

One of hot topics in the solar physics are the so-called 'stealth' coronal mass ejections (CME), which are not associated with any appreciable energy release events in the lower corona, such as the solar flares. It is often assumed recently…

We report on the 2024 September 9 sustained gamma ray emission (SGRE) event observed by the Large Area Telescope (LAT) onboard the Fermi satellite. The event was associated with a backside solar eruption observed by multiple spacecraft such…

Context. Acoustic waves in the Sun are affected by the atmospheric layers, but this region is often ignored in forward models due to the increase in computational cost. Aims. The purpose of this work is to take into account the solar…

The rapid neutron-capture process (r-process) is responsible for the creation of roughly half of the elements heavier than iron, including precious metals like silver, gold, and platinum, as well as radioactive elements such as thorium and…

We investigate the relationship between the gamma-ray emission measured with Fermi-LAT and radio signatures of coronal shock waves in four behind-the-limb (BTL) solar flares. All events were associated with metric type II radio burst. Both…

Type III radio bursts are a signature of the flux of near-relativistic electrons ejected during solar flares. These bursts are frequently observed by spacecraft such as the Parker Solar Probe. It is traditionally believed that these…

We have obtained spectroscopic observations for four short-period variable objects detected in ZTF, Gaia, and Pan-STARRS (ZGP) data and classified as Blue Large-Amplitude Pulsators (BLAPs) in McWhirter and Lam (2022): ZGP-BLAP-03,…