太阳与恒星天体物理
The Chern-Pontryagin density of the Sun's Kerr field, ${}^*RR\simeq 288\,G^{2}M_{\odot}^{2}a_{\odot}\cos\theta/c^{4}r^{7}$, provides an annually sign-changing parity-odd curvature invariant sampled by a detector in the Solar System and…
Models of eclipsing binaries require the assignment of appropriate emergent intensities to the surface elements of the binary components. For distance-dependent modelling of flux-calibrated light curves, this necessitates an approximation…
We introduce Stellar J-Harvesting (SJH), a technosignature in which an engineered system extracts rotational angular momentum from a star. Unlike a classical Dyson sphere, such a system need not produce a detectable mid-infrared excess; its…
Protoplanetary disks represent a crucial stage in the evolution of Young Stellar Objects towards the formation of fully formed planetary systems. While substantial progress has been made in the last decades in the characterization of the…
Quasi-periodic pulsations (QPPs) have been observed in a broad electromagnetic spectrum, encompassing radio, ultraviolet, white light, X-rays, and Gama-rays. Yet, flare-associated QPPs remain rarely detected in mid-infrared emission. Here,…
Understanding the origin of coherent solar radio bursts requires linking macroscopic coronal structures with the kinetic processes responsible for wave generation. We investigate emissions from slowly positively drifting bursts (SPDBs), a…
Recent observations of young galaxies in the high-redshift Universe reveal signs of early enrichment of nitrogen. Extremely massive stars ($M \gtrsim 10^{2}-10^3\,M_\odot$) with strong stellar winds have been proposed as a potential driver…
We present a minimal analytic framework to investigate the star formation efficiency per free-fall time, $\epsilon_{\rm ff}$, in giant molecular clouds (GMCs), focusing on the origin of the observed clustering around $\epsilon_{\rm ff} \sim…
We present a comprehensive multi-wavelength spectroscopic and photometric analysis of the 44 confirmed white dwarfs within 13 pc of the Sun. Combining flux-calibrated ultraviolet (UV) spectroscopy from the Hubble Space Telescope (STIS and…
Stellar activity is the main barrier to detecting and/or confirming low-mass/long-period (and Earth-analogue) planets using radial-velocity (RV) measurements. Searching for reliable indicators that better trace magnetic activity may be key…
We present a systematic test of formalisms for common envelope evolution by forward-modelling observable post-common envelope binaries. We compare predictions from the $\alpha$-formalism, and the Two-stage and SCATTER formalisms against…
Emission-line stars classified as Be exhibit light and colour variability on various timescales, ranging from days to decades. Their evolution must be constrained by long-term observations that are accurately calibrated and stable. Here, we…
The continuum is understood to contain a large portion of the energy emitted by a solar flare. The optical continuum, known as white light (WL), is particularly relevant since it may be observed by ground-based instruments. We measured the…
The VRIC light curves were regularly measured for two eclipsing binaries, NSVS 01031772 and 2MASS J04100497+2931023 as part of our long-term observational project to study low-mass eclipsing binaries with a short orbital period and surface…
For low-mass stars (M < 1.4 Msun), the connection between stellar rotation and magnetic activity governs stellar spin-down, shapes the environments of their exoplanets, and provides an age-diagnostic via magneto-gyro-chronology. Recently,…
In the present work, we use a phase-resolved methodology for the detection and characterisation of non-stationary QPPs in the hard X-ray lightcurves observed from the HEL1OS instrument onboard Aditya-L1 mission, complemented by…
This self-contained theoretical study treats incompressible, free-boundary flows in a gravitating, ideal hydromagnetic star abutting vacuum, centered on the steady field-aligned flows of Chandrasekhar, Prendergast and Tsinganos, together…
Circumbinary disks are commonly observed around post-asymptotic giant branch (post-AGB) star binaries, yet their formation and especially their long-term evolution remain unclear. We investigate this process using smoothed-particle…
Classical Be stars exhibit mass ejection events that feed their viscous decretion disks. Recent TESS space photometry and simultaneous spectroscopy revealed that these flickers are localised, short-lived, and associated with near-Keplerian…
The symbiotic recurrent nova (SyRNe) TCrB (T-Coronae Borealis) is perhaps the most famous example of the group of known four symbiotic nova systems, for which at least two previous nova eruptions are known and accurately recorded: in 1866…