Exploring Ancient Stars: What White Dwarfs Tell Us About the Universe
This study examines white dwarfs in the globular cluster M 4 using JWST and HST data to refine age estimates and test stellar evolution models. Researchers confirmed theoretical predictions of cooling sequences and identified faint infrared excess in some stars, hinting at unexplained phenomena like debris disks or companions. The findings place M 4’s age at about 12.2 billion years, slightly younger than similar clusters, while future observations aim to unravel these mysteries further.
Unveiling the Hidden Beats: The Richest Pulsating Ultra-Massive White Dwarf
Researchers discovered WD J0135+5722, the richest pulsating ultra-massive white dwarf, with 19 distinct pulsation modes. Its mass (1.12–1.15 solar masses) and crystallized core fraction (56–86%) suggest a complex interior, possibly composed of carbon-oxygen or oxygen-neon. This discovery advances asteroseismology and sheds light on stellar evolution and remnants.
Tracing the Origins of Alpha-Poor, Very Metal-Poor Stars
Alpha-poor very metal-poor stars are rare stars with unique chemical signatures, primarily explained by core-collapse supernova ejecta. Some stars also show contributions from sub-Chandrasekhar Type Ia supernovae. Pair-instability supernovae play a minimal role, highlighting the diversity of processes shaping early cosmic chemical evolution.
A Cosmic Clue: A Gravitational Wave Candidate for Supernova Origins
ATLAS J1138-5139, a compact binary white dwarf system with a 28-minute orbit, is a promising Type Ia supernova progenitor and detectable gravitational wave source. Its mass transfer and evolution provide critical insights into supernova origins and binary evolution. This system serves as a key target for future gravitational wave observatories like LISA, advancing multi-messenger astronomy.
The Early Rise of Nova V1674 Herculis: Unveiling the Secrets of Fast Novae
The paper by Quimby et al. (2024) discusses the early stages of the outburst of Nova V1674 Herculis, a fast nova observed in unprecedented detail from 10 magnitudes below its peak brightness. The authors analyze the nova's rapid rise, which showed three distinct phases: a slow, fast, and faster rise, captured by high-cadence observations from Evryscope. They propose models that explain this rise by the expansion of the white dwarf's outer layers, though some features, such as the rapid transitions, remain unexplained.