2025-12-05 ミシガン大学
Images of Nova Herculis 2021 (V1674 Her) taken with the CHARA Array, two and three days after the eruption began. The images show two outflows expanding in nearly perpendicular directions, forming an hourglass-like structure consistent with theoretical predictions, which are illustrated in the rightmost artistic impression. Image credit: CHARA Array/NASA GSFC
＜関連情報＞
- https://news.umich.edu/seeing-stellar-explosions-in-high-definition/
- https://www.nature.com/articles/s41550-025-02725-1
新星の初期画像から明らかになった多重流出と遅延放出 Multiple outflows and delayed ejections revealed by early imaging of novae
Elias Aydi,John D. Monnier,Antoine Mérand,Gail H. Schaefer,Laura Chomiuk,Magdalena Otulakowska-Hypka,Jhih-Ling Fan,Kwan Lok Li,Kirill V. Sokolovsky,Ricardo Salinas,Michael Tucker,Benjamin Shappee,Richard Rudy,Kim L. Page,N. Paul M. Kuin,David A. H. Buckley,Peter Craig,Luca Izzo,Justin Linford,Brian D. Metzger,Koji Mukai,Marina Orio,Ken J. Shen,Jay Strader,… Anna V. Payne
Nature Astronomy Published:05 December 2025
DOI:https://doi.org/10.1038/s41550-025-02725-1
Abstract
Novae are thermonuclear eruptions on accreting white dwarfs in interacting binaries. Although most of the accreted envelope is expelled, the mechanism—impulsive ejection, multiple outflows or prolonged winds, or a common-envelope interaction—remains uncertain. Gigaelectronvolt γ-ray detections from >20 Galactic novae establish these eruptions as nearby laboratories for shock physics and particle acceleration, underscoring the need to determine how novae eject their envelopes. Here we report on near-infrared interferometry, supported by multiwavelength observations, of two γ-ray-detected novae. The images of the very fast 2021 nova V1674 Her, taken just 2–3 days after discovery, reveal the presence of two perpendicular outflows. The interaction between these outflows probably drives the observed γ-ray emission. Conversely, the images of the very slow 2021 nova V1405 Cas suggest that the bulk of the accreted envelope was ejected more than 50 days after the eruption began, as the nova slowly rose to its visible peak, during which the envelope engulfed the system in a common-envelope phase. These images offer direct observational evidence that the mechanisms driving mass ejection from the surfaces of accreting white dwarfs are not as simple as previously thought, revealing multiple outflows and delayed ejections.
