太阳与恒星天体物理
We present 225 and 350 GHz imaging of the iconic T Tauri system using the Atacama Large Millimeter submillimeter Array (ALMA). T Tauri is a hierarchical triple system, and the close binary T Tau Sa/Sb underwent periastron passage in March…
We perform numerical simulations to investigate high-power wind accretion in massive binary systems undergoing enhanced mass-loss episodes. The primary star is taken in the mass range $M_{1} = 60$--$90\,\mathrm{M_{\odot}}$, while the…
The third Gaia data release includes 33.8 million radial velocity measurements, extending to a magnitude of G_RVS = 14. To reach this magnitude limit, spectra were processed down to a signal-to-noise ratio (S/N) of 2. In this very low S/N…
Understanding and monitoring solar active regions is essential for operational space-weather forecasting and improved solar dynamo modeling. This requires comprehensive 360-degree observations of the Sun. While space-weather forecasting has…
Flare flux reflect contribution from active regions rather than the whole hemisphere of a star. Unlike the amplitude of light-curves caused by starspots, the flare detection is independent of inclination. The two valuable properties of…
Massive Population III stars are currently not observed, but their initial mass function (IMF) can be inferred through stellar archaeology: fitting core-collapse supernova yield models to elemental abundances of low-mass, long-lived…
The Alpha Cygni (ACYG) variables are blue-white supergiants which display low-amplitude brightness variations of around 0.1 magnitude. The prototype Deneb shows quasi-periodic variations of around 12 days, interrupted by intervals of…
We present observations and a magnetic-reconnection scenario of a twin pair of "atypical flares" that occurred on 2022 April 22 in a quadrupolar magnetic configuration formed by two active regions. The spatio-temporal evolution of the two…
We have examined how the characteristics of the tachocline -- i.e., the change in rotation rate $\delta\Omega$, or the "jump", the position of the midpoint of the tachocline, $r_d$, and the width of the tachocline, $w_d$, -- change as a…
Negative superhumps are photometric modulations in cataclysmic variables with periods slightly shorter than the orbital period. They are usually attributed to retrograde nodal precession of a tilted accretion disk, although the origin and…
Numerous white dwarf stars are known to be orbited by disks of gas and dust. To date, broad, about 300 km s-1 wide, gaseous circumstellar absorption features have only been reported for the already iconic WD 1145+017, where one is…
We report the results of a radial velocity monitoring program in the Hyades region, carried out at the Center for Astrophysics over a period of more than 45 yr. Nearly 12,000 spectra were gathered for 625 stars brighter than $V \approx…
Intense solar eruptions occasionally accelerate solar energetic particles (SEPs) and can trigger ground-level enhancements (GLEs). Among the 77 known GLEs, the first four GLEs, #1 -- 4 in the 1940s took place before the advent of the…
Recent observational studies of red giant stars have estimated the visibility of their mixed oscillation modes, which is a proxy of the average energy of these modes. Among other things, they demonstrated that although the damping rate of…
Context: The Necklace nebula is a bipolar, post-common-envelope planetary nebula, the central star of which has been shown to have a dwarf carbon star companion. Aims: We aim to understand the origins of the Necklace and its dwarf carbon…
Electron-capture supernovae (ECSNe) are commonly thought to result in a collapse to a neutron star. Recent work has shown that a thermonuclear explosion is also a possible outcome. The division between the two regimes has not yet been…
The formation and early evolution of protoplanetary disks are governed by a wide variety of physical processes during a gravitational collapse. Observations have begun probing disks in their earliest stages, and have favored the…
Massive stars are the key engines of the Universe. However, their evolution and thus their ionizing feedback are still not fully understood. One of the largest gaps in current stellar evolution calculations is the lack of a model for the…
Decayless kink oscillations are frequently observed in solar coronal loops and are considered potential contributors to coronal heating. Despite the ubiquity of this wave phenomenon, its driving mechanism remains unclear. Studies to derive…
Many Wolf-Rayet (WR) stars have optically thick winds that cloak the hydrostatic layers of the underlying star. In these cases, traditional spectral analysis methods are plagued by degeneracies that make it difficult to constrain parameters…